Proyectos De Electronica.

Recopilado por: Eddy Vilca Electrónica-2008

Light switch

General Description This project will let you make a switch that will be activated by light falling on a sensor. It is a very useful device and can be used in automatism’s, security systems, counters, remote controls etc. It is very sensitive, fast acting and reliable. The circuit uses a Light Dependent Resistor (LDR) as a sensor and three transistors to amplify the signals from the LDR and drive the relay which does the switching. Technical Specifications - Characteristics Working voltage: ......... 12 VDC Maximum current: ....... 50 mA How it Works As you can see from the circuit diagram in the input of the circuit there is a trimmer (R7) connected in series with the LDR in such a way as to form a voltage divider. When light falls on the LDR it causes its resistance to change and this causes the voltage across the LDR to change accordingly. These voltage changes are used to change the state of the transistor TR2 switching it ON and OFF. The output from TR2 drives TR1 and this in turn TR3 which drives the output relay. The diode D1 protects the transistor from the back emf that is produced from the relay coil when it is turned off. The trimmer R7 adjusts the sensitivity of the circuit so it is possible to use it under widely different conditions. The circuit operates from a 9-12 VDC power supply and the relay contacts are rated at 250 V/2 A. Construction First of all let us consider a few basics in building electronic circuits on a printed circuit board. The board is made of a thin insulating material clad with a thin layer of conductive copper that is shaped in such a way as to form the necessary conductors between the various components of the circuit. The use of a properly designed printed circuit board is very desirable as it speeds construction up considerably and reduces the possibility of making errors. Smart Kit boards also come predrilled and with the outline of the components and their identification printed on the component side to make construction easier. To protect the board during storage from oxidation and assure it gets to you in perfect condition the copper is tinned during manufacturing and covered with a special varnish that protects it from getting oxidised and makes soldering easier. Soldering the components to the board is the only way to build your circuit and from the way you do it depends greatly your success or failure. This work is not very difficult and if you stick to a few rules you should have no problems. The soldering iron that you use must be light and its power should not exceed the 25 Watts. The tip should be fine and must be kept clean at all times. For this purpose come very handy specially made sponges that are kept wet and from time to time you can wipe the hot tip on them to remove all the residues that tend to accumulate on it. DO NOT file or sandpaper a dirty or worn out tip. If the tip can not be cleaned, replace it. There are many different types of solder in the market and you should choose a good quality one that contains the necessary flux in its core, to assure a perfect joint every time. DO NOT use soldering flux apart from that which is already included in your solder. Too much flux can cause many problems and is one of the main causes of circuit malfunction. If nevertheless you have to use extra flux, as it is the case when you have to tin copper wires, clean it very thoroughly after you finish your work. In order to solder a component correctly you should do the following:

Recopilado por: Eddy Vilca Electrónica-2008 Clean the component leads with a small piece of emery paper - Bend them at the correct distance from the component body and insert the component in its place on the board. You may sometimes find a component with heavier gauge leads than usual, that are too thick to enter in the holes of the p.c. board. In this case use a mini drill to increase the diameter of the holes slightly. Do not make the holes too large as this is going to make soldering difficult afterwards. Take the hot iron and place its tip on the component lead while holding the end of the solder wire at the point where the lead merges from the board. The iron tip must touch the lead slightly above the p.c. board. When the solder starts to melt and flow wait till it covers evenly the area around the hole and the flux boils and gets out from underneath the solder. The whole operation should not take more than 5 seconds. Remove the iron and leave the solder to cool naturally without blowing on it or moving the component. If everything was done properly the surface of the joint must have a bright metallic finish and its edges should be smoothly ended on the component lead and the board track. If the solder looks dull, cracked, or has the shape of a blob then you have made a dry joint and you should remove the solder (with a pump, or a solder wick) and redo it. Take care not to overheat the tracks as it is very easy to lift them from the board and break them. When you are soldering a sensitive component it is good practice to hold the lead from the component side of the board with a pair of long-nose pliers to divert any heat that could possibly damage the component. Make sure that you do not use more solder than it is necessary as you are running the risk of short-circuiting adjacent tracks on the board, especially if they are very close together. After finishing your work cut off the excess of the component leads and clean the board thoroughly with a suitable solvent to remove all flux residues that still remain on it. You shouldn’t face any special problems with this project. The only unusual component is the LDR and you should decide where you want to put your project and how you are going to activate it as it will be necessary to leave a hole in the case for the sensor and possibly orientated the whole case towards the light beam. As usual start building the circuit with the resistors leaving the LDR for the final stage. Mount the relay on the board and solder the transistors and the diode in their places making sure that nothing went in the wrong place or the wrong way round. When everything is in its place solder the LDR carefully, as it is very fragile and can be easily damaged if overheated. Make the last visual check and if you are satisfied that all is well you can connect the circuit to a power supply or a battery of at least 9 VDC. Cover the sensitive surface of the LDR and turn the trimmer till you hear the relay clicking. If you uncover the sensor the relay should click again. You will probably have to read just the trimmer once the circuit is cased and you are ready to use it in some application, in order to fine-tune it to the conditions that you want it to operate in. Warning Smart kits are sold as stand alone training kits. If they are used as part of a larger assembly and any damage is caused, our company bears no responsibility. While using electrical parts, handle power supply and equipment with great care, following safety standards as described by international specs and regulations. If it does not work Check the power supply to make sure there are at least 9 VDC across the circuit, and that the polarity is correct. Make sure the transistors and the diode are connected the right way round. Check your work for possible dry joints, bridges across adjacent tracks or soldering flux residues that usually cause problems. Electronic Diagrams.

Recopilado por: Eddy Vilca Electrónica-2008

R = light resistor R1 = 4,7 K R2 = 1,2 K R3 = 2,2 K R4 = 1,2 K R5 = 1,2 K R6 = 2,7 K R7 = 100 K C1 = 10 μf/16V TR1 = BC107-BC108 NPN (CV7644) TR2 = BC107-BC108 NPN (CV7644) TR3 = BC557-BC558-BC327 PNP D1 = 1N4148 Diode RELAY = 12V relay

Recopilado por: Eddy Vilca Electrónica-2008

Touch Switch Technical Specifications - Characteristics Supply voltage: 12 VDC Max. current:30 mA Relay rating: 250 V/2 A How it Works The circuit as you can see from its diagram is very simple and only uses 8 components. The heart of the circuit is the IC CD 4011 that is connected as a FLIP-FLOP. Pins 9 and 13 of the IC are the «SET» and «RESET» contacts of the FLIP-FLOP. The IC is of the CMOS type and requires a very low current to in its gates to control it. This high sensitivity of the circuit makes the touch operation possible. The two gates are held at logic state «1» continuously by means of the two resistors R1 and R3 that connect them to the positive supply rail. These resistors have a very large resistance of 10 Mohm. If we now touch a set of contacts the skin resistance closes the circuit between the corresponding gate and the negative supply rail. The skin resistance for small areas of the skin is normally much lower than 10 Mohm and the gate is effectively brought to logic condition «0» which makes the FLIP-FLOP change state. For any given state of the FLIP-FLOP touching the corresponding set of contacts will make the circuit to reverse its state of balance and in effect toggle the switch. As a switch is used a relay driven by a transistor which is driven from the out put of the FLIP-FLOP. Construction First of all let us consider a few basics in building electronic circuits on a printed circuit board. The board is made of a thin insulating material clad with a thin layer of conductive copper that is shaped in such a way as to form the necessary conductors between the various components of the circuit. The use of a properly designed printed circuit board is very desirable as it speeds construction up considerably and reduces the possibility of making errors. Smart Kit boards also come predrilled and with the outline of the components and their identification printed on the component side to make construction easier. To protect the board during storage from oxidation and assure it gets to you in perfect condition the copper is tinned during manufacturing and covered with a special varnish that protects it from getting oxidised and makes soldering easier. Soldering the components to the board is the only way to build your circuit and from the way you do it depends greatly your success or failure. This work is not very difficult and if you stick to a few rules you should have no problems. The soldering iron that you use must be light and its power should not exceed the 25 Watts. The tip should be fine and must be kept clean at all times. For this purpose come very handy specially made sponges that are kept wet and from time to time you can wipe the hot tip on them to remove all the residues that tend to accumulate on it. DO NOT file or sandpaper a dirty or worn out tip. If the tip cannot be cleaned, replace it. There are many different types of solder in the market and you should choose a good quality one that contains the necessary flux in its core, to assure a perfect joint every time. DO NOT use soldering flux apart from that which is already included in your solder. Too much flux can cause many problems and is one of the main causes of circuit malfunction. If nevertheless you have to use extra flux, as it is the case when you have to tin copper wires, clean it very thoroughly after you finish your work. In order to solder a component correctly you should do the following: Clean the component leads with a small piece of emery paper. - Bend them at the correct distance from the component body and insert the component in its place on the board. You may find sometimes a component with heavier gauge leads than usual, that are too thick to enter in the holes of the p.c. board. In this case use a mini drill to enlarge the holes slightly. Do not make the holes too large as this is going to make soldering difficult afterwards.

Recopilado por: Eddy Vilca Electrónica-2008 Take the hot iron and place its tip on the component lead while holding the end of the solder wire at the point where the lead emerges from the board. The iron tip must touch the lead slightly above the p.c. board. When the solder starts to melt and flow wait till it covers evenly the area around the hole and the flux boils and gets out from underneath the solder. The whole operation should not take more than 5 seconds. Remove the iron and let the solder to cool naturally without blowing on it or moving the component. If everything was done properly the surface of the joint must have a bright metallic finish and its edges should be smoothly ended on the component lead and the board track. If the solder looks dull, cracked, or has the shape of a blob then you have made a dry joint and you should remove the solder (with a pump, or a solder wick) and redo it.

Take care not to overheat the tracks as it is very easy to lift them from the board and break them. When you are soldering a sensitive component it is good practice to hold the lead from the component side of the board with a pair of long-nose pliers to divert any heat that could possibly damage the component. Make sure that you do not use more solder than it is necessary as you are running the risk of short-circuiting adjacent tracks on the board, especially if they are very close together. - After having finished your work cut off the excess of the component leads and clean the board thoroughly with a suitable solvent to remove all flux residues that still remain on it. The switch only has eight components and its construction is very easy even for the most inexperienced. As usual construction must start from the least sensitive to heat components, which in this case are the IC socket and the pins. After soldering the pins and the socket, make the two jumper connections that are marked on the component side of the board, solder the relay in its place and continue with the transistor the diode and the LED. Once everything is in its place clean the board very well from flux residues and check it for short circuits and possible mistakes. Then, place the IC in its socket. The IC is of the CMOS family and should be handled with great care as it can be damaged very easily from static discharges. Avoid touching its pins and keep your body and the circuit board grounded during insertion. You should also take care not to bent any pins underneath the IC body during this operation. Now connect the points marked + & - on the board with 12 VDC and touch lightly the set of contacts marked «ON». You should hear the clicking of the relay and the LED should light up. (In case the LED turns on at power up then touch the other set of contacts that are marked «OFF».) Touching the contacts marked «OFF» will turn the LED off and the relay should be released. It is up to you to connect any device you want to control with the touch switch but please remember that you should not exceed the power rating of the relay which is 250 V/2 A.

Recopilado por: Eddy Vilca Electrónica-2008

Dimensions 5,5cm x 4,2cm If it does not work Check your work for possible dry joints, bridges across adjacent tracks or soldering flux residues that usually cause problems. -Check again all the external connections to and from the circuit to see if there is a mistake there. See that there are no components missing or inserted in the wrong places. Make sure that all the polarised components have been soldered the right way round. Make sure the supply has the correct voltage and is connected the right way round to your circuit. Make sure that you have inserted the IC in its socket correctly and that you have not bent any pins during insertion. Check your project for faulty or damaged components. Parts R1:...........10MOhm 1/4 W R2:...........10MOhm 1/4 W R3:........... 1KOhm 1/4 W D1:........... Led red

D2:...........1N4148 diode TR1:.........BC558 PNP Transistor - BC327 IC1:..........CD4011 CMOS IC RL1:..........12V relay rated at 250 V / 2A

Recopilado por: Eddy Vilca Electrónica-2008

IR Remote Control Extender Circuit Description: This is an improved IR remote control extender circuit. It has high noise immunity, is resistant to ambient and reflected light and has an increased range from remote control to the extender circuit of about 7 meters. It should work with any domestic apparatus that use 36-38kHz for the IR carrier frequency. Please note that this is NOT compatible with some satellite receivers that use 115KHz as a carrier frequency. Notes:

The main difference between this version and the previous circuit, is that this design uses a commercially available Infra Red module. This module, part number IR1 is available from Harrison Electronics in the UK. The IR module contains a built in photo diode, amplifier circuit and buffer and decoder. It is centerd on the common 38kHz carrier frequency that most IR controls use. The module removes most of the carrier allowing decoded pulses to pass to the appliance. Domestic TV's and VCR's use extra filtering is used to completely remove the carrier. The IR1 is packaged in a small aluminium case, the connections viewed from underneath are shown below: How It works: The IR1 module (IC3) operates on 5 Volt dc. This is provided by the 7805 voltage regulator, IC1. Under quiescent (no IR signal) conditions the voltage on the output pin is high, around 5 volts dc. This needs to be inverted and buffered to drive the IR photo emitter LED, LED2. The buffering is provided by one gate (pins 2 & 3) of a hex invertor the CMOS 4049, IC2. The IR1 module can directly drive TTL logic,but a pull-up resistor, R4 is required to interface to CMOS IC's. This resistor ensures that the signal from a remote control will alternate between 0 and 5 volts. As TTL logic levels are slightly different from CMOS, the 3.3k resistor R4 is wired to the +5 volt supply line ensuring that the logic high signal will be 5 volts and not the TTL levels 3.3 volts. The resistor does not affect performance of the IR module, but DOES ensure that the module will correctly drive the CMOS buffer without instability. The output from the 4049 pin 2 directly drives transistor Q1, the 10k resistor R1 limiting base current. LED1 is a RED LED, it will flicker to indicate when a signal from a remote control is received. Note that in this circuit, the carrier is still present, but at a reduced level, as well as the

Recopilado por: Eddy Vilca Electrónica-2008 decoded IR signal. The CMOS 4049 and BC109C transistor will amplify both carrier and signal driving LED2 at a peak current of about 120 mA when a signal is received. If you try to measure this with a digital meter, it will read much less, probably around 30mA as the meter will measure the average DC value, not the peak current. Any equipment designed to work between 36 and 40kHz should work, any controls with carrier frequencies outside this limit will have reduced range, but should work. The exception here is that some satellite receivers have IR controls that use a higher modulated carrier of around 115KHz. At present, these DO NOT work with my circuit, however I am working on a Mark 3 version to re-introduce the carrier. Parts List: C1 100u 10V C2 100n polyester R1 10k R2 1k R3 33R 1W R4 3k3 Q1 BC109C IC1 LM7805 IC2 CMOS 4049B IC3 IR1 module from Harrison Electronics See Last paragraph LED1 Red LED (or any visible colour) LED2 TIL38 or part YH70M from Maplin Electronics Pinouts for the IC's can be found on my IC pinout page, click here. Testing: This circuit should not present too many problems. If it does not work, arm yourself with a multimeter and perform these checks. Check the power supply for 12 Volt dc. Check the regulator output for 5 volt dc. Check the input of the IR module and also Pin 1 of the 4049 IC for 5 volts dc. With no remote control the output at pin 2 should be zero volts. Using a remote control pin 2 will read 5 volts and the Red LED will flicker. Measuring current in series with the 12 volt supply should read about 11mA quiescent, and about 40/50mA with an IR signal. If you still have problems measure the voltage between base and emitter of Q1. With no signal this should be zero volts, and rise to 0.6-0.7 volts dc with an IR signal. Any other problems, please email me, but please do the above tests first. PCB Template: Once again a PCB template has been kindly drafted for this project by Domenico.

Recopilado por: Eddy Vilca Electrónica-2008

Frost Alarm

Notes: The thermistor used has a resistance of 15k at 25 degrees and 45k at 0 degrees celsius. A suitable bead type thermistor is found in the Maplin catalogue. The 100k pot allows this circuit to trigger over a wide range of temperatures. A slight amount of hysteresis is provided by inclusion of the 270k resistor. This prevents relay chatter when temperature is near the switching threshold of this circuit.

Sound Operated Switch

Recopilado por: Eddy Vilca Electrónica-2008 Notes: This sensitive sound operated switch can be used with a dynamic microphone insert as above, or be used with an electret (ECM) microphone. If an ECM is used then R1 (shown dotted) will need to be included. A suitable value would be between 2.2k and 10kohms. The two BC109C transitors form an audio preamp, the gain of which is controlled by the 10k preset. The output is further amplified by a BC182B transistor. To prevent instability the preamp is decoupled with a 100u capacitor and 1k resistor. The audio voltage at the collector of the BC182B is rectified by the two 1N4148 diodes and 4.7u capacitor. This dc voltage will directly drive the BC212B transistor and operate the relay and LED. It should be noted that this circuit does not "latch". The relay and LED operate momentarily in response to audio peaks.

UltraSonic Radar General Description This is a very interesting project with many practical applications in security and alarm systems for homes, shops and cars. It consists of a set of ultrasonic receiver and transmitter which operate at the same frequency. When something moves in the area covered by the circuit the circuit’s fine balance is disturbed and the alarm is triggered. The circuit is very sensitive and can be adjusted to reset itself automatically or to stay triggered till it is reset manually after an alarm.

Technical Specifications - Characteristics Working voltage: 12V DC Current: 30 mA How it Works As it has already been stated the circuit consists of an ultrasonic transmitter and a receiver both of which work at the same frequency. They use ultrasonic piezoelectric transducers as output and input devices respectively and their frequency of operation is determined by the particular devices in use. The transmitter is built around two NAND gates of the four found in IC3 which are used here wired as inverters and in the particular circuit they form a multivibrator the output of which drives the transducer. The trimmer P2 adjusts the output frequency of the transmitter and for greater efficiency it should be made the same as the frequency of resonance of the transducers in use. The receiver similarly uses a transducer to receive the signals that are reflected back to it the output of which is amplified by the transistor TR3, and IC1 which is a 741 op-amp. The output of IC1 is taken to the non inverting input of IC2 the amplification factor of which is adjusted by means of P1. The circuit is adjusted in such a way as to stay in balance as long the same as the output frequency of the transmitter. If there is some movement in the area covered by the ultrasonic emission the signal that is reflected back to the receiver becomes distorted and the circuit is thrown out of balance. The output of IC2 changes abruptly and the Schmitt trigger circuit which is built around the remaining two gates in IC3 is triggered. This drives the output transistors TR1,2 which in turn give a signal to the alarm system or if there is a relay connected to the circuit, in series with the collector of TR1, it becomes activated. The circuit works from 9-12 VDC and can be used with batteries or a power supply.

Recopilado por: Eddy Vilca Electrónica-2008

Construction First of all let us consider a few basics in building electronic circuits on a printed circuit board. The board is made of a thin insulating material clad with a thin layer of conductive copper that is shaped in such a way as to form the necessary conductors between the various components of the circuit. The use of a properly designed printed circuit board is very desirable as it speeds construction up considerably and reduces the possibility of making errors. Smart Kit boards also come pre-drilled and with the outline of the components and their identification printed on the component side to make construction easier. To protect the board during storage from oxidation and assure it gets to you in perfect condition the copper is tinned during manufacturing and covered with a special varnish that protects it from getting oxidised and also makes soldering easier. Soldering the components to the board is the only way to build your circuit and from the way you do it depends greatly your success or failure. This work is not very difficult and if you stick to a few rules you should have no problems. The soldering iron that you use must be light and its power should not exceed the 25 Watts. The tip should be fine and must be kept clean at all times. For this purpose come very handy specially made sponges that are kept wet and from time to time you can wipe the hot tip on them to remove all the residues that tend to accumulate on it. DO NOT file or sandpaper a dirty or worn out tip. If the tip cannot be cleaned, replace it. There are many different types of solder in the market and you should choose a good quality one that contains the necessary flux in its core, to assure a perfect joint every time. DO NOT use soldering flux apart from that which is already included in your solder. Too much flux can cause many problems and is one of the main causes of circuit malfunction. If nevertheless you have to use extra flux, as it is the case when you have to tin copper wires, clean it very thoroughly after you finish your work. In order to solder a component correctly you should do the following: @Clean the component leads with a small piece of emery paper. @Bend them at the correct distance from the component’s body and insert the component in its place on the board. @You may find sometimes a component with heavier gauge leads than usual, that are too thick to enter in the holes of the p.c. board. @In this case use a mini drill to enlarge the holes slightly. Do not make the holes too large as this is going to make soldering difficult afterwards.

Recopilado por: Eddy Vilca Electrónica-2008 @Take the hot iron and place its tip on the component lead while holding the end of the solder wire at the point where the lead emerges from the board. The iron tip must touch the lead slightly above the p.c. board. @When the solder starts to melt and flow wait till it covers evenly the area around the hole and the flux boils and gets out from underneath the solder. The whole operation should not take more than 5 seconds. Remove the iron and allow the solder to cool naturally without blowing on it or moving the component. If everything was done properly the surface of the joint must have a bright metallic finish and its edges should be smoothly ended on the component lead and the board track. If the solder looks dull, cracked,or has the shape of a blob then you have made a dry joint and you should remove the solder (with a pump, or a solder wick) and redo it. @Take care not to overheat the tracks as it is very easy to lift them from the board and break them. @When you are soldering a sensitive component it is good practice to hold the lead from the component side of the board with a pair of long-nose pliers to divert any heat that could possibly damage the component. @Make sure that you do not use more solder than it is necessary as you are running the risk of short-circuiting adjacent tracks on the board, especially if they are very close together. @When you finish your work cut off the excess of the component leads and clean the board thoroughly with a suitable solvent to remove all flux residues that may still remain on it. @There are quite a few components in the circuit and you should be careful to avoid mistakes that will be difficult to trace and repair afterwards. Solder first the pins and the IC sockets and then following if that is possible the parts list the resistors the trimmers and the capacitors paying particular attention to the correct orientation of the electrolytic. @Solder then the transistors and the diodes taking care not to overheat them during soldering. The transducers should be positioned in such a way as they do not affect each other directly because this will reduce the efficiency of the circuit. When you finish soldering, check your work to make sure that you have done everything properly, and then insert the IC’s in their sockets paying attention to their correct orientation and handling IC3 with great care as it is of the CMOS type and can be damaged quite easily by static discharges. Do not take it out of its aluminium foil wrapper till it is time to insert it in its socket, ground the board and your body to discharge static electricity and then insert the IC carefully in its socket. In the kit you will find a LED and a resistor of 560 — which will help you to make the necessary adjustments to the circuit. Connect the resistor in series with the LED and then connect them between point 9 of the circuit and the positive supply rail (point 1). Connect the power supply across points 1 (+) and 2 (-) of the p.c. board and put P1 at roughly its middle position. Turn then P2 slowly till the LED lights when you move your fingers slightly in front of the transducers. If you have a frequency counter then you can make a much more accurate adjustment of the circuit. Connect the frequency counter across the transducer and adjust P2 till the frequency of the oscillator is exactly the same as the resonant frequency of the transducer. Adjust then P1 for maximum sensitivity. Connecting together pins 7 & 8 on the p.c. board will make the circuit to stay triggered till it is manually reset after an alarm. This can be very useful if you want to know that there was an attempt to enter in the place which are protected by the radar.

Recopilado por: Eddy Vilca Electrónica-2008

Adjustments This kit does not adjustments, if you instructions.

need any follow the building Warning

If they are used as part of a larger assembly and any damage is caused, our company bears no responsibility. While using electrical parts, handle power supply and equipment with great care, following safety standards as described by international specs and regulations. If it does not work Check your work for possible dry joints, bridges across adjacent tracks or soldering flux residues that usually cause problems. Check again all the external connections to and from the circuit to see if there is a mistake there. See that there are no components missing or inserted in the wrong places. Make sure that all the polarised components have been soldered the right way round. Make sure that the supply has the correct voltage and is connected the right way round to your circuit. Check your project for faulty or damaged components. If everything checks and your project still fails to work, please contact your retailer and the Smart Kit Service will repair it for you. Componets R1 = 180 KOhm R2 = 12 KOhm R3, 8 = 47 KOhm R4 = 3,9 KOhm R5, 6, 16 = 10 KOhm R7, 10, 12, 14, 17 = 100 KΩ R9, 11 = 1 MOhm R13, 15 = 3,3 KOhm

C1, 6 = 10uF/16V C2 = 47uF/16V C3 = 4,7 pF C4, 7 = 1 nF C5 = 10nF C8, 11 = 4,7 uF/16V C9 = 22uF/16V C10 = 100 nF C12 = 2,2 uF/16V C13 = 3,3nF C14 = 47nF

TR1, 2, 3 = BC547 , BC548 P1 = 10 KOhm trimmer P2 = 47 KOhm trimmer IC1, 2 = 741 OP-AMP IC3 = 4093 C-MOS R = TRANSDUCER 40KHz T = TRANSDUCER 40KHz D1, 2, 3, 4 = 1N4148

Infra Red Remote Control Extender Description This circuit is used to relay signals from an Infra Red remote control in one room to an IR controlled appliance in another room. Forward I have seen these devices advertised in magazines, they sell for around £40-£50 and use radio to transmit between receiver and transmitter. This version costs under £5 to make and uses a cable connection between receiver and transmitter. For example, if you have a bedroom TV set that is wired to the video or satellite in another room, then you can change channels on the

Recopilado por: Eddy Vilca Electrónica-2008 remote satellite receiver using this circuit. The idea is that you take your remote control with you, aim at the IR remote control extender which is in the same room, and this will relay the IR signal and control the remote appliance for you. The circuit is displayed below:

Parts List: 1 SFH2030 Photodiode 1 TIL38 IR emitting diode 1 5mm Red LED 2 4.7M 1/4W resistors 1 1k 1/4W resistor 1 2.2k 1/4W resistor 1 27ohm 1/2W resistor 1 BC337 transistor 1 CA3140 MOSFET opamp The LPC661 opamp Radio Shack # 900-6332 can be used as a substitute for the CA3140 Circuit Benefits This circuit has an advantage over other similar designs in that there is nothing to adjust or setup. Also bellwire or speaker cable can be used to remotely site the IR emitting diode, since this design uses low output impedance and will not pick up noise. Some systems require coaxial cable which is expensive and bulky. The wireless variety of remote control extenders need two power supplies, here one is used and being radio are inevitably EM noise pollution. A visual indication of the unit receiving an Infra Red signal is provided by LED1. This is an ordinary coloured LED, I used orange but any colour will do. You will see LED1 flash at a rate of 4 - 40Hz when a remote control button is pressed. LED0 is an Infra Red Emitter Diode, this is remotely wired in the room with the appliance to be controlled. I used the type SFH487 which has a peak wavelength of 880nm. This is available in the UK from Maplin Electronics, order code CY88V. Most IR remote controls operate at slightly different wavelengths, between the range of 850 950nm. If you cannot obtain the SFH487 then any IR emitter diode that has an output in the above range should work. About IR Remote Controls As previously stated IR remote controls use wavelengths between 850 - 950nm. At this short wavelength, the light is invisible to the human eye, but a domestic camcorder can actually view

Recopilado por: Eddy Vilca Electrónica-2008 this portion of the electromagnetic spectrum. Viewed with a camcorder, an IR LED appears to change brightness. All remote controls use an encoded series of pulses, of which there are thousands of combinations. The light output intensity varies with each remote control, remotes working at 4.5V dc generally will provide a stronger light output than a 3V dc control. Also, as the photodiode in this project has a peak light response at 850nm, it will receive a stronger signal from controls operating closer to this wavelength. The photodiode will actually respond to IR wavelengths from 400nm to 1100nm, so all remote controls should be compatible. Circuit Description The receiver is built around a silicon photodiode, the SFH2030 available from Maplin, order code CY90X. This photodiode is very sensitive and will respond to a wide spectral range of IR frequencies. There is a small amount of infra red in direct sunlight, so make sure that the diode does not pick up direct sunlight. If this happens, LED1 will be constantly lit. There is a version of the SFH2030 that has a daylight filter built in, the SFH2030F order code CY91Y. A TIL100 will also give good results here. A photodiode produces minute pulses of current when exposed to infra red radiation. This current (around 1uA with the SFH2030 and a typical IR control used at a distance of 1 meter) is amplified by the CA3140 opamp. This is configured as a differential amplifier and will produce an output of about 1 volt per uA of input current. The photodiode, can be placed up to a meter or so away from the circuit. Screened cable is not necessary, as common mode signals (noise) will be rejected. It is essential to use a MOSFET input type here as there is zero output offset and negligible input offset current. A 741 or LF351 can not be used in this circuit. The output from the opamp is amplified by the BC337 operating in common emitter mode. As a MOSFET opamp IC is used, its quiescent voltage output is zero and this transistor and both LED's will not be lit. The 1k resistor makes sure that the BC337 will fully saturate and at the same time limits base current to a safe level. Operating an IR remote control and pointing at the photodiode (SFH2030) will cause both LED's to illuminate, you will only see the visable coloured LED (LED1) which will flicker. Remote controls use a system of pulse code modulation, so it is essential that the signal is not distorted by any significant amount. Direct coupling, and a high speed switching transistor avoid this problem. Construction No special PCB is required, I built my prototype on a small piece of Veroboard. The pinout for the CA3140 is shown below. Note that only the pins labeled in the schematic are used, pins 1, 5 and 8 are not used and left unconnected.

Alignment There is nothing to set-up or adjust in this circuit. The only thing to watch is that the emitting diode is pointing at the controlled device (video, CD player, etc). I found that the beam was quite directional. Also make sure that there is a direct line of sight involved. It will not work if a 5 foot spider plant gets in the way, for example. I had a usable range at 5 meters, but possibly more distance may be possible. As a check, place a dc volt meter across the 27 ohm resistor. It should read 0 volts, but around 2 or 3 volts when a remote control is aimed at the photodiode. Specifications of Prototype Having made my prototype, I ran a few tests :-

Recopilado por: Eddy Vilca Electrónica-2008 Current consumption 2mA standby 2mA standby IR receiver range < 1 meter IR transmitter range > 5 meters

60mA operating ( with 12V supply) 85mA operating (with 15V supply)

It is difficult to measure the IR transmitter range as this is dependent upon a number of factors. The type of infra red control used and its proximity to the receiving photodiode, the voltage supply, the wavelength and efficiency of the IR emitter and the sensitivity of the controlled appliance all affect overall performance. In Use The reception range of the IR remote control to the photodiode depends on the strength of the remote control, but I had a working range of a meter or so, this needs bearing in mind when placing the circuit. Its also a good idea to wire LED1, the coloured LED near to the photodiode, that way, you know that the unit has received a signal. The IR emitter has a larger range, I had no problems at 5 meters but may possibly work further distances. The emitting diodes are quite directional, so make sure it is aimed directly at the appliance to be controlled. The IR emitting diode is small and can be placed out of sight. I drilled a small hole above the door frame. The emitter diode leads were insulated and pushed through this hole, leaving an inch or so to adjust the angle and position of the LED. From a distance, the clear plastic lens of the diode could not be seen. Final Comments and Fault Finding To date this has proved to be one of the most popular circuits on my site. Of all the email I receive about this circuit, most problems relate to the Infra Red photo diode. You must make sure that this is pointed away from sunlight, or use a type with daylight filter, otherwise LED1 will be constantly lit, and LED0 will be in operation also. This will draw excessive current and in some case overheat the BC337. The main problem is when using a different photo diode to the SFH2030. Any other photo diode LED should work, but you need to know its operating wavelength range beforehand. This will generally be described in the manufacturers data sheet or possibly described if you order from an electronic component catalogue. With these last two points in mind, you should be rewarded with a useful and working circuit. PCB Template This has been very kindly drafted by Domenico from Italy. First the copper side: A magnified view from the component side is shown below:

Recopilado por: Eddy Vilca Electrónica-2008

Fridge door Alarm Circuit diagram:

Parts: R1____________10K 1/4W Resistor R2___________Photo resistor (any type) R3,R4________100K 1/4W Resistors C1____________10nF 63V Polyester Capacitor C2___________100΅F 25V Electrolytic Capacitor D1,D2_______1N4148 75V 150mA Diodes IC1___________4060 14 stage ripple counter and oscillator IC Q1___________BC337 45V 800mA NPN Transistor

Recopilado por: Eddy Vilca Electrónica-2008 BZ1__________Piezo sounder (incorporating 3KHz oscillator) SW1__________Miniature SPST slide Switch B1___________3V Battery (2 AA 1.5V Cells in series) Circuit operation: This circuit, enclosed in a small box, is placed in the fridge near the lamp (if any) or the opening. With the door closed the interior of the fridge is in the dark, the photo resistor R2 has a high resistance (>200K) thus clamping IC1 by holding pin 12 high. When a beam of light enters from the opening, or the fridge lamp lights, the photo resistor lowers its resistance (<2K), pin 12 goes low, IC1 starts counting and, after a preset delay (20 seconds in this case) the piezo sounder beeps for 20 sec. then stops for the same lapse of time and the cycle repeats until the fridge door closes. D2 connected to pin 6 of IC1 makes the piezo sounder beeping 3 times per second. Notes: •

Connecting D1 to pin 2 of IC1 halves the delay time.

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Delay time can be varied changing C1 and/or R3 values.

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Any photo resistor type should work well.

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Current drawing is insignificant, so SW1 can be eliminated.

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Place the circuit near the lamp and take it away when defrosting, to avoid circuit damage due to excessive moisture.

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Don't place it in the freezer.

Recopilado por: Eddy Vilca Electrónica-2008

Capacitive Sensor

Parts: R1,R2_____1M 1/4W Resistors R3,R4____47K 1/4W Resistors C1_______10΅F 25V Electrolytic Capacitor C2______470pF 630V Ceramic or Polyester Capacitor D1-D3____1N4002 100V 1A Diodes Q1-Q3_____BC337 45V 800mA NPN Transistors RL1_______Relay with SPDT 2A @ 220V switch Coil Voltage 12V. Coil resistance 200-300 Ohm J1________Two ways output socket Sensor____Aluminium or copper thin sheet with the dimensions of a post-card, glued at the rear of the same (approx. 15x10.5 cm.) Thin screened cable

Circuit description: The purpose of this circuit is to animate shop-windows by means of a capacitive sensor placed behind a post-card-like banner. The card is placed against the glass inside the shop-window, and the visitor can activate the relay placing his hand on the card, from the outside. Especially suited for toy-shops, the circuit can activate model trains, small electric racing cars, lights etc. Further applications are left at user's imagination. Adopt it to increase the impact of your shopwindow on next Christmas season! Q1, Q2 & Q3 form a high impedance super-Darlington that drives the relay, amplifying the 50Hz alternate mains-supply frequency induced in the sensor by the human body. C1 & D2, D3 ensure a clean relay's switching. Power supply can be any commercial wall plug-in transformer with rectifier and smoothing capacitor, capable of supplying the voltage and current necessary to power the relay you intend to use. Note: For proper operation, circuit ground must be connected via a small value, high voltagerating capacitor to one side of the mains supply socket. The "Live" side is the right one.

Infra-red Level Detector

Recopilado por: Eddy Vilca Electrónica-2008

Parts: R1_____________10K R2,R5,R6,R9_____1K R3_____________33R R4,R8___________1M R7_____________10K R10____________22K

1/4W Resistor 1/4W Resistors 1/4W Resistor 1/4W Resistors Trimmer Cermet 1/4W Resistor

C1,C4___________1΅F 63V Electrolytic or Polyester Capacitors C2_____________47pF 63V Ceramic Capacitor C3,C5,C6______100΅F 25V Electrolytic Capacitors D1_____________Infra-red LED D2_____________Infra-red Photo Diode (see Notes) D3,D4________1N4148 75V 150mA Diode D5______________LED (Any color and size) D6,D7________1N4002 100V 1A Diodes Q1____________BC327 45V 800mA PNP Transistor IC1_____________555 Timer IC IC2___________LM358 Low Power Dual Op-amp IC3____________7812 12V 1A Positive voltage regulator IC RL1____________Relay with SPDT 2A @ 220V switch Coil Voltage 12V. Coil resistance 200-300 Ohm J1_____________Two ways output socket

Device purpose: This circuit is useful in liquids level or proximity detection. It operates detecting the distance from the target by reflection of an infra-red beam. It can safely detect the level of a liquid in a tank without any contact with the liquid itself. The device's range can be set from a couple of cm. to about 50 cm. by means of a trimmer. Range can vary, depending on infra-red transmitting and receiving LEDs used and is mostly affected by the color of the reflecting surface. Black surfaces lower greatly the device's sensitivity. Circuit operation: IC1 forms an oscillator driving the infra-red LED by means of 0.8mSec. pulses at 120Hz frequency and about 300mA peak current. D1 & D2 are placed facing the target on the same line, a couple of centimeters apart, on a short breadboard strip. D2 picks-up the infra-red beam

Recopilado por: Eddy Vilca Electrónica-2008 generated by D1 and reflected by the surface placed in front of it. The signal is amplified by IC2A and peak detected by D4 & C4. Diode D3, with R5 & R6, compensate for the forward diode drop of D4. A DC voltage proportional to the distance of the reflecting object and D1 & D2 feeds the inverting input of the voltage comparator IC2B. This comparator switches on and off the LED and the optional relay via Q1, comparing its input voltage to the reference voltage at its non-inverting input set by the Trimmer R7. Notes: •

Power supply must be regulated (hence the use of IC3) for precise reference voltages. The circuit can be fed by a commercial wall plug-in power supply, having a DC output voltage in the range 12-24V.

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Current drawing: LED off 40mA; LED and Relay on 70mA @ 12V DC supply.

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R10, C6, Q1, D6, D7, RL1 and J1 can be omitted if relay operation is not required.

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The infra-red Photo Diode D2, should be of the type incorporating an optical sunlight filter: these components appear in black plastic cases. Some of them resemble TO92 transistors: in this case, please note that the sensitive surface is the curved, not the flat one.

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Avoid sun or artificial light hitting directly D1 & D2.

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Usually D1-D2 optimum distance lies in the range 1.5-3 cm.

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If you are needing a similar circuit driving 3 LEDs in sequence, also suitable as a parking aid.

Field-strength meter

Parts: R1____________330K 1/4W Resistor R2____________100R 1/4W Resistor C1_____________10nF 63V Polyester or Ceramic Capacitor C2____________100΅F 25V Electrolytic Capacitor Q1____________BC547 45V 100mA NPN Transistor Q2____________BC327 45V 800mA PNP Transistor SW1____________Reed Switch and small magnet (See Notes) SPKR___________8 Ohm Loudspeaker (See Notes) B1_____________3V Battery (two A or AA cells wired in series etc.)

Device purpose:

Recopilado por: Eddy Vilca Electrónica-2008 This circuit, enclosed in a small plastic box, can be placed into a bag or handbag. A small magnet is placed close to the reed switch and connected to the hand or the clothes of the person carrying the bag by means of a tiny cord. If the bag is snatched abruptly, the magnet looses its contact with the reed switch, SW1 opens, the circuit starts oscillating and the loudspeaker emits a loud alarm sound. The device can be reverse connected, i.e. the box can be placed in a pocket and the cord connected to the bag. This device can be very useful in signalling the opening of a door or window: place the box on the frame and the magnet on the movable part in a way that magnet and reed switch are very close when the door or window is closed. Circuit operation: A complementary transistor-pair is wired as a high efficiency oscillator, directly driving a small loudspeaker. Low part-count and 3V battery supply enable a very compact construction. Notes: •

The loudspeaker can be any type, its dimensions are limited only by the box that will contain it.

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An on-off switch is unnecessary because the stand-by current drawing is less than 20΅A.

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Current consumption when the alarm is sounding is about 100mA.

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If the circuit is used as anti-bag-snatching, SW1 can be replaced by a 3.5mm mono Jack socket and the magnet by a 3.5mm. mono Jack plug with its internal leads shorted. The Jack plug will be connected with the tiny cord etc.

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Do not supply this circuit with voltages exceeding 4.5V: it will not work and Q2 could be damaged. In any case a 3V supply is the best compromise.

Recopilado por: Eddy Vilca Electrónica-2008

Voice activated switch

This circuit uses an MC2830 to form a voice activated switch ( VOX ). A traditional VOX circuit is unable to distinguish between voice and noise in the incoming signal. In a noisy environment, the switch is often triggered by noise, or the activation sensitivity must be turned down. This circuit overcomes this weakness. The switch is activated by voice level above the noise and not activated by background noise. This is done by utilizing the differences in voice and noise waveforms. Voice waveforms generally have a wide range of variation in amplitude, whereas noise waveforms are more stable. The sensitivity of the voice activation depends on the value of R6. The voice activation sensitivity is reduced from 3.0dB to 8.0dB above the noise if R6 changes from 14k to 7.0k .

Metal Detector

The circuit described here is that of a metal detector. The opera- tion of the circuit is based on superheterodyning principle which is commonly used in superhet receivers. The circuit utilises

Recopilado por: Eddy Vilca Electrónica-2008 two RF oscillators. The frequencies of both oscillators are fixed at 5.5 MHz. The first RF oscillator comprises transistor T1 (BF 494) and a 5.5MHz ceramic filter commonly used in TV sound-IF section. The second oscillator is a Colpitt’s oscillator realised with the help of transistor T3 (BF494) and inductor L1 (whose construction details follow) shunted by trimmer capacitor VC1. These two oscillators’ frequencies (say Fx and Fy) are mixed in the mixer transistor T2 (another BF 494) and the difference or the beat frequency (Fx-Fy) output from collector of transistor T2 is connected to detector stage comprising diodes D1 and D2 (both OA 79). The output is a pulsating DC which is passed through a low-pass filter realised with the help of a 10k resistor R12 and two 15nF capacitors C6 and C10. It is then passed to AF amplifier IC1 (2822M) via volume control VR1 and the output is fed to an 8-ohm/1W speaker. The inductor L1 can be constructed using 15 turns of 25SWG wire on a 10cm (4-inch) diameter air-core former and then cementing it with insulating varnish. For proper operation of the circuit it is critical that frequencies of both the oscillators are the same so as to obtain zero beat in the absence of any metal in the near vicinity of the circuit. The alignment of oscillator 2 (to match oscillator 1 frequency) can be done with the help of trimmer capacitor VC1. When the two frequencies are equal, the beat frequency is zero, i.e. beat frquency=Fx-Fy=0, and thus there is no sound from the loudspeaker. When search coil L1 passes over metal, the metal changes its inductance, thereby changing the second oscillator’s frequency. So now Fx-Fy is not zero and the loudspeaker sounds. Thus one is able to detect presence of metal.

Water level buzzer

Specifications Water Level Buzzer is a simple kit which will buzz when water reaches the sensor level. •

Input - 9 VDC @ 40 mA

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Output ??? Buzzer

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Terminal pins for supply voltage

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Power-On LED indicator

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Four mounting holes of 3.2 mm each

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PCB dimensions 32 mm x 35 mm

Recopilado por: Eddy Vilca Electrónica-2008

Simple but reliable car battery tester

Recopilado por: Eddy Vilca Electrónica-2008

This circuit uses the popular and easy to find LM3914 IC. This IC is very simple to drive, needs no voltage regulators (it has a built in voltage regulator) and can be powered from almost every source. This circuit is very easy to explain: When the test button is pressed, the Car battery voltage is feed into a high impedance voltage divider. His purpose is to divide 12V to 1,25V (or lower values to lower values). This solution is better than letting the internal voltage regulator set the 12V sample voltage to be feed into the internal voltage divider simply because it cannot regulate 12V when the voltage drops lower (linear regulators only step down). Simply wiring with no adjust, the regulator provides stable 1,25V which is fed into the precision internal resistor cascade to generate sample voltages for the internal comparators. Anyway the default setting let you to measure voltages between 8 and 12V but you can measure even from 0V to 12V setting the offset trimmer to 0 (but i think that under 9 volt your car would not start). There is a smoothing capacitor (4700uF 16V) it is used to adsorb EMF noise produced from the ignition coil if you are measuring the battery during the engine working. Diesel engines would not need it, but i'm not sure. If you like more a point graph rather than a bar graph simply disconnect pin 9 on the IC (MODE) from power. The calculations are simple (default) For the first comparator the voltage is : 0,833 V corresponding to 8 V

Recopilado por: Eddy Vilca Electrónica-2008 * * * * * voltage is : 0,875 V corresponding to 8,4 V ... .. for the last comparator the voltage is : 1,25 V corresponding to 12 V Have fun, learn and don't let you car battery discharge...

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