Trans Miss Or Tv Link

ffd8ffe000104a4649460001020100a100a10000ffe20c584943435f5052 4f46494c4500010100000c484c696e6f021000006d6e747252474220585 95a2007ce00020009000600310000616373704d534654000000004945 4320735247420000000000000000000000000000f6d6000100000000d3 2d4850202000000000000000000000000000000000000000000000000 000000000000000000000000000000000000000000000001163707274 000001500000003364657363000001840000006c77747074000001f000 000014626b707400000204000000147258595a0000021800000014675 8595a0000022c000000146258595a0000024000000014646d6e640000 025400000070646d6464000002c400000088767565640000034c00000 08676696577000003d4000000246c756d69000003f8000000146d65617 30000040c0000002474656368000004300000000c725452430000043c0 000080c675452430000043c0000080c625452430000043c0000080c746 5787400000000436f70797269676874202863292031393938204865776 c6574742d5061636b61726420436f6d70616e790000646573630000000 000000012735247422049454336313936362d322e3100000000000000 0000000012735247422049454336313936362d322e310000000000000

00000000000000000000000000000000000000000

TV

T

Use it to rebroadcast video signals ffd8ffe000104a4649460001020100a100a10000ffe20c584943435f50524f4 6494c4500010100000c484c696e6f021000006d6e74725247422058595a20 07ce00020009000600310000616373704d53465400000000494543207352 47420000000000000000000000000000f6d6000100000000d32d485020200 000000000000000000000000000000000000000000000000000000000000

000000000000000000000000000000000116370727400000150000000336 4657363000001840000006c77747074000001f000000014626b7074000002 04000000147258595a00000218000000146758595a0000022c0000001462 58595a0000024000000014646d6e640000025400000070646d6464000002 c400000088767565640000034c0000008676696577000003d4000000246c7 56d69000003f8000000146d6561730000040c000000247465636800000430 0000000c725452430000043c0000080c675452430000043c0000080c62545 2430000043c0000080c7465787400000000436f7079726967687420286329 2031393938204865776c6574742d5061636b61726420436f6d70616e79000 0646573630000000000000012735247422049454336313936362d322e310 00000000000000000000012735247422049454336313936362d322e31000 000000000000000000000000000000000000000000000000000 throughout your house. BY MARC SPIWAK

One of the most useful gadgets a video enthusiast can have is a low-power TV Transmitter. Such a device can transmit a signal from a VCR to any TV in a home or backyard. Imagine the convenience of being able to sit by the pool watching your favorite movie on a portable with a tape or laserdisc playing indoors. You could even retransmit cable TV for your own private viewing. Videotapes can be dubbed from one VCR to another without a cable connecting the two machines together. When connected to a video camera, a TV transmitter can be used in surveillance for monitoring a particular location. The main problem a video enthusiast has in obtaining a TV transmitter is that a commercial units are expensive. However, we have some good news! You can build the TV Transmitter described here for less POPtronixTV Transmitter www.poptronix.com1

ffd8ffe000104a46494600010201005900590000ffe20c584943435f50524f46494c45000 10100000c484c696e6f021000006d6e74725247422058595a2007ce0002000900060031 0000616373704d53465400000000494543207352474200000000000000000000000000 00f6d6000100000000d32d4850202000000000000000000000000000000000000000000 0000000000000000000000000000000000000000000000000000011637072740000015 00000003364657363000001840000006c77747074000001f000000014626b7074000002 04000000147258595a00000218000000146758595a0000022c000000146258595a0000 024000000014646d6e640000025400000070646d6464000002c4000000887675656400 00034c0000008676696577000003d4000000246c756d69000003f8000000146d6561730 000040c0000002474656368000004300000000c725452430000043c0000080c67545243 0000043c0000080c625452430000043c0000080c7465787400000000436f70797269676 874202863292031393938204865776c6574742d5061636b61726420436f6d70616e7900 00646573630000000000000012735247422049454336313936362d322e310000000000 00000000000012735247422049454336313936362d322e310000000000000000000000 00000000000000000000000000000000 than $30 in one evening! The easiest way to do that is to order the kit that‚s available from the source given in the Parts List (a custom case for the kit is also available). Nevertheless, we present enough information here to build the TV Transmitter from scratch. The TV Transmitter combines line-level audio and video signals, and transmits the resulting signal up to 300 feet. The circuit can be powered from a 9-volt battery. It is suggested that a 12-volt DC supply during be used during the alignment procedure. This would insure maximum transmission range and best possible picture. Aligning the TV Transmitter requires no special equipment whatsoever, and it is a very

simple procedure. The Transmitter's output can be tuned to be received on any TV channel from 2 to 6. The range of channels is wide enough so that the unit will not interfere with other TV viewers who are nearby. To comply with FCC rules, it is mandatory the nearby TV viewers are not disturbed by the transmission. If your activities interfere with the reception from a licensed station, regardless of the reason, you must shut down your unit.

Circuit Description Figure 1 is the schematic diagram of the TV Transmitter circuit. Video signals input at jack J1 are first terminated by resistor R6 and coupled through capacitor C1 to clamping-diode D1. The clamping forces the sync pulses to a fixed DC level to reduce blooming effects. Potentiometer R3 is used to set the gain of the video signal; its effect is similar to that of the contrast control on a TV set. Bias-control R7 can be used to adjust the black level of the picture so that some level of signal is transmitted, even for a totally dark picture. That way, a TV receiver can maintain proper sync. As we'll get to later, potentiometers R3 and R7 are cross adjusted for the best all-around performance. RF-transformer T1 and its internal capacitor form the tank circuit of a Hartley oscillator that's tuned to 4.5 megahertz. Audio signals input at J2 are coupled to the base of Q3 via C2 and R4: the audio signal modulates the base signal of Q3 to form an audio subcarrier that‚s 4.5-megahertz higher than the videocarrier frequency. The FM modulated subcarrier is applied to the modulator section through C5 and R9. Resistor R9 adjusts the level of the subcarrier with respect to the video signal. Transistors Q1 and Q2 amplitude modulate the video and audio signals onto an RF-carrier signal. The operating frequency is set by coil L4, which is 3.5 turns of 24- gauge enameled wire on a form containing a standard ferrite slug. Fig. 1. The schematic shows how easy it is to hook up the TV Transmitter to other equipment. There is a video-input jack, J1; an audio-input jack, J2; and an external- antenna jack, J3. You could eliminate the latter because the unit works fine with just an installed telescoping antenna.

2POPtronixTV Transmitter www.poptronix.com That coil is part of a Colpitts tank circuit also containing C7 and C9. The tank circuit forms Q4's feedback network, so Q4 oscillates at the set frequency The RF output from the oscillator section is amplified by Q5 and Q6, whose supply voltage comes from the modulator section. Antenna matching and low-pass filtering is performed by C12, C13, and L1. Resistor R12 is optional; it is added to help match the output signal to any kind of antenna. (More on that in a moment.)

Construction Before we go on, while it is certainly possible to build the unit from scratch. However, unless you are an experienced builder and an accomplished parts scrounger, it is strongly recommended that you purchase the complete kit, or, at the very least, the component kit from the source mentioned in the Parts List. While most of the parts are readily available, some can be a real headache to obtain. The 4.5-MHz RF transformer (T1) used in the kit is an OEM Toko part that is not available via traditional sources. While just about any 4.5-MHz RF transformer that is similar to the one described in the article (internal capacitor, tapped secondary) can be used, such units are hard to obtain from hobbyist-friendly sources. If you are determined to go that route, your best bet is to contact Toko directly (1250 Feehanville Dr.. Mt, Prospect, IL 60056; Tel. 708-297-0070) to obtain the location of your nearest full-line distributor. Also, coil L4 is a custom unit. It can, however, be home made using the parameters given earlier.

The Transmitter should be built on a PC board for best performance. You can make a board from the foil pattern provided in Fig. 2, or use the one that’s included with the kit. Parts are installed on the board as shown in the parts-placement diagram [see Fig. 3). Pay careful attention to the orientation of the transistors, electrolytic capacitors. and the diode. If resistor R12 (not included in the kit) is used, it must be tack- soldered on the solder side of the board between the antenna output and ground. That resistor should be installed if ffd8ffe000104a46494600010201005900590000ffe20c584943435f50524f46494c4500010100000c484c69 6e6f021000006d6e74725247422058595a2007ce00020009000600310000616373704d534654000000004 9454320735247420000000000000000000000000000f6d6000100000000d32d4850202000000000000000 000000000000000000000000000000000000000000000000000000000000000000000000000000001163 707274000001500000003364657363000001840000006c77747074000001f000000014626b70740000020 4000000147258595a00000218000000146758595a0000022c000000146258595a0000024000000014646d 6e640000025400000070646d6464000002c400000088767565640000034c0000008676696577000003d40 00000246c756d69000003f8000000146d6561730000040c0000002474656368000004300000000c725452 430000043c0000080c675452430000043c0000080c625452430000043c0000080c7465787400000000436f 70797269676874202863292031393938204865776c6574742d5061636b61726420436f6d70616e7900006 46573630000000000000012735247422049454336313936362d322e31000000000000000000000012735 247422049454336313936362d322e3100000000000000000000000000000000000000000000000000000 0

you intend

This case allows easy access to the circuit board

to use for alignment purposes.

anything other than the built- in whip to provide proper matching between the antenna and the circuit. T h e

s w i t c h

o f t replacement.

any kind of toggle switch as a

h e

o u t l i n e

you can use thisA

simple whip

Fig. 2.

( S 1 an te nn a

) that is shown in Fig. 3 is the same as the one that comes with the kit, an SPST push-button switch that is normally open. You can use mounts to the foil pattern diagram board with a single machine screw: The to make your own

PC boardTransmitter. for the TV ffd8ffe000104 a46494600010 201005a005a0 000ffe20c5849 43435f50524f4 6494c4500010 100000c484c6 96e6f0210000

06d6e747252 47422058595 a2007ce0002 00090006003 10000616373 704d5346540 00000004945 43207352474 20000000000

00 00 00 00 00 00 00 00 00

f6d6000100000000d32d4 850202000000000000000 000000000000000000000 000000000000000000000 000000000000000000000 000000000000000001163 707274000001500000003 364657363000001840000 006c77747074000001f000

000014626b70 740000020400 000014725859 5a0000021800 000014675859 5a0000022c00 000014625859 5a0000024000 000014646d6e 640000025400 000070646d64 64000002c400 000088767565 640000034c00 000086766965 77000003d400 0000246c756d 69000003f800 0000146d6561 730000040c00 000024746563 680000043000 00000c725452 430000043c00 00080c675452 430000043c00 00080c625452 430000043c00 00080c746578 740000000043 6f7079726967 687420286329 203139393820 4865776c6574 742d5061636b 61726420436f ffd8ffe000104 a46494600010 201005a005a0 000ffe20c5849 43435f50524f4 6494c4500010 100000c484c6 96e6f0210000 06d6e7472524 7422058595a2 007ce0002000 900060031000 0616373704d5 346540000000 049454320735

6d70616e790 00064657363 00000000000 00012735247 42204945433 6313936362d 322e3100000 00000000000 00000012735 24742204945 43363139363 62d322e3100 00000000000 00000000000 00000000000 00000000000 00000000 ffd8ffe00010 4a464946000 10201005a00 5a0000ffe20c 584943435f5 0524f46494c 45000101000 00c484c696e 6f021000006 d6e74725247 422058595a2 007ce000200 09000600310 00061637370 4d534654000 00000494543 20735247420 00000000000 24742000000 00000000000 00000000000 f6d60001000 00000d32d48 50202000000 00000000000 00000000000 00000000000 00000000000 00000000000 00000000000 00000000000 00000000000 01163707274 00000150000

00 00 00 00 00 00 00 00 f6 d6 00 01 00 00 00 00 d3 2d 48 50 20 20 00 00 00 00 00 00 00 00 00 00 00 00 00 00

000000000000000000000 000000000000000000000 000000000000000000000 000116370727400000150 000000336465736300000 1840000006c7774707400 0001f000000014626b707 400000204000000147258 595a00000218000000146 758595a0000022c000000 146258595a00000240000 00014646d6e6400000254 00000070646d646400000 2c4000000887675656400 00034c000000867669657 7000003d4000000246c75 6d69000003f8000000146 d6561730000040c000000 247465636800000430000 0000c725452430000043c 0000080c6754524300000 43c0000080c6254524300 00043c0000080c7465787 400000000436f70797269 676874202863292031393 938204865776c6574742d 5061636b61726420436f6 d70616e79000064657363 000000000000001273524 742204945433631393636 2d322e310000000000000 000000000127352474220 49454336313936362d322 e31000000000000000000 000000000000000000000 000000000000000

00 03 36 46 57 36 30 00 00 18 40 00 00 06 c7 77

47074000001f000000014 626b70740000020400000 0147258595a0000021800 0000146758595a0000022 c000000146258595a0000 024000000014646d6e640 000025400000070646d64 64000002c400000088767 565640000034c00000086 76696577000003d400000 0246c756d69000003f8000 000146d6561730000040c 000000247465636800000 4300000000c7254524300 00043c0000080c6754524 30000043c0000080c6254

52430000043c 0000080c7465 787400000000 436f70797269 676874202863 292031393938 204865776c65

m3

ffd8ffe000104 a46494600010 20100c800c80 000ffe20c5849 43435f50524f4 6494c4500010 100000c484c6 96e6f0210000 06d6e7472524 7422058595a2 007ce0002000 900060031000 0616373704d5 346540000000 049454320735 247420000000 000000000000 000000000f6d 600010000000 0d32d4850202 000000000000 000000000000 000000000000 000000000000 000000000000

74742d50616 36b61726420 436f6d70616 e7900006465 73630000000 00000001273 52474220494

54 33 63 13 93 63 62

00000000000 00000000000 00000000000 00116370727 40000015000 00003364657 36300000184 0000006c777 47074000001 f0000000146 26b70740000 02040000001 47258595a00 00021800000 0146758595a 0000022c000 00014625859 5a000002400 0000014646d 6e640000025 40000007064 6d646400000 2c400000088 76756564000 0034c000000 86766965770 00003d40000 B1

00 24 6c 75 6d 69 00 00 03 f8 00 00 00 14 6d 65 61 73 00 00 04 0c 00 00 00 24 74

d322e3100000000000000 000000001273524742204 9454336313936362d322e 310000000000000000000 000000000000000000000 00000000000000

656368000004300000000 c725452430000043c0000 080c675452430000043c0 000080c62545243000004 3c0000080c74657874000 00000436f707972696768 742028632920313939382 04865776c6574742d5061 636b61726420436f6d706 16e790000646573630000 000000000012735247422 049454336313936362d32 2e3100000000000000000 000001273524742204945 4336313936362d322e310 000000000000000000000 000000000000000000000 00000000000 whip antenna is suitable for most applications. The battery holder can be soldered to the board with scraps of jumper wire or mounted with double-sided tape or screws. +

*SEE TEXT

When the board is finished, it must be

mounted in a case. The case available from Ramsey Electronics allows the board to be mounted in

th e bo tto m hal f,

and by lifting the top off, still be aligned. That also protects the underside of the board against shorts during alignment. You should inspect the solder side of the board carefully before mounting it in the case.

Alignment To align the TV Transmitter, you'll need a TV receiver and a source of video such as a VCR or camcorder. You'll also need a nonmetallic tool to adjust coil L4 and transformer T1. A fresh 9-volt battery can be used for alignment, but if you find it is difficult to align, try doing it with a 12volt supply. Note that during alignment and testing, we found that the unit operated much better from 12 volts. If you find the same to be true, it is a simple matter to add an external power jack to the unit and wire it to the appropriate points on the PC board. Tune a TV receiver to an unused channel between 2 and 6. The

Fig. 3. Building the project is easy if

TV must have an indoor antenna connecte d directly to it; an outdoor antenna or cable won't work. Make sure both potentio meters are in midposition and apply power to the Transmitt er. Adjust L4 with a nonmetall ic tool until the TV screen goes blank. Then fineadjust L4 for the "mostblank" picture. Conne ct the video and audio outputs from a

you use this partsplacement diagram. Resistor

VC R to jac ks J1 an d J2 (re spe ctiv ely ) of the Tra ns mit ter, ANT1 Then se t a vi d e o ta p e to pl a y. Y o u sh o ul d se e a R1 2 mu

picture on the TV screen: if you do, readjust L4 for the best picture; if you don't, check the board for any bad connections. Next, adjust R3 for the best picture brightness and R7 for the best overall picture. You might have to make another minor adjustment to L4 after R3 and R7 are set. Finally, adjust T1 with a nonmetallic tool for the best sounding audio. That‚s all there is to it. The whip antenna should be fine for most in-home use. If you need more range, an external antenna can be connected to J3 (remember to install R12). But always keep in mind that it is your responsibility to make sure that your operation does not interfere with your neighbor's TV viewing. st be tack-soldered on the solder side of the board between the antenna output and ground.

4POPtronixTV Transmitter www.poptronix.com ffd8ffe000104a46494 60001020100c800c80 000ffe20c584943435f 50524f46494c4500010 100000c484c696e6f02 1000006d6e74725247 422058595a2007ce00 020009000600310000 616373704d53465400 000000494543207352 474200000000000000 00000000000000f6d6 000100000000d32d48 502020000000000000 000000000000000000 000000000000000000 000000000000000000 000000000000000000 000000000011637072 740000015000000033 646573630000018400 00006c777470740000 01f000000014626b70 740000020400000014 7258595a0000021800 0000146758595a0000 022c00000014625859 5a0000024000000014 646d6e640000025400 000070646d64640000 02c400000088767565 640000034c00000086 76696577000003d400 0000246c756d690000 03f8000000146d6561 730000040c00000024 746563680000043000 00000c725452430000 043c0000080c675452 430000043c0000080c 625452430000043c00 00080c746578740000 0000436f7079726967 687420286329203139 3938204865776c6574 742d5061636b617264 20436f6d70616e7900 006465736300000000 000000127352474220 49454336313936362d 322e31000000000000 000000000012735247 422049454336313936 362d322e3100000000 000000000000000000 000000000000000000 0000000000

ffd8ffe00010 4a464946000 1020100c800 c80000ffe20c 584943435f5 0524f46494c 45000101000 00c484c696e 6f021000006 d6e74725247 422058595a2 007ce000200 09000600310 00061637370 4d534654000 00000494543 20735247420 00000000000 00000000000 00000f6d600 0100000000d 32d48502020 00000000000 00000000000 00000000000 00000000000 00000000000 00000000000 00000000000 00000000000 00000011637 07274000001 50000000336 46573630000 01840000006 c7774707400 0001f000000 014626b7074 00000204000 00014725859 5a000002180 00000146758 595a0000022 c0000001462 58595a00000 24000000014 646d6e64000 00254000000 70646d64640 00002c40000 00887675656 40000034c00 00008676696

57 70 00 00 3d 40 00 00 02 46 c7 56 d6 90 00 00 3f 80 00 00 01 46 d6 56 17 30 00 00 40 c0 00 00 02 47 46 56 36 80 00 00 43 00 00 00 00 c7 25 45 24 30 00 00 43

c0000080c675452430000 043c0000080c625452430 000043c0000080c746578 7400000000436f7079726 967687420286329203139 3938204865776c6574742 d5061636b61726420436f 6d70616e7900006465736 300000000000000127352 474220494543363139363 62d322e31000000000000 000000000012735247422 049454336313936362d32 2e3100000000000000000 000000000000000000000 0000000000000000

Copyright © 1997, POPtronix Inc. All rights reserved. As a service to readers, POPtronix, Inc. publishes available plans or information relating to newsworthy products, techniques and scientific and technologic al developme nts. Because of possible

v a r i a n c e s i n t h e q u a l i t y a n d c o n d i t i o n o f m a t e r i

a l s a n d w o r k m a n s h i p u s e d b y

a n y r e s p o n s i b i l i t y f o r t h e

r e a d e r s ,

s a f e

w e

p r o p e r

d i s c l a i m

a n d

f u n c

tioning of reader-built projects based upon or from plans or information published online. Since some of the equipment and circuitry described in POPtronix, Inc. Project Articles may relate to or be covered by U.S. patents, we disclaim any liability for the infringemen t of such patents by the making, using, or selling of any such equipment or circuitry, and suggest that anyone interested in such projects consult a patent attorney.

POPtronixTV Transmitter www.poptronix.com5