Temperature
This document was uploaded by user and they confirmed that they have the permission to share it. If you are author or own the copyright of this book, please report to us by using this DMCA report form. Report DMCA
Overview
Download & View Temperature as PDF for free.
More details
- Words: 212
- Pages: 2
Temperature-controlled 12V dc Fan Suitable for computer cooling fans LED motor speed indicator Circuit diagram:
Parts: R1______________15K R2_______________1K5 R3_______________1K R4_____________270R R5______________22K R6_____________680R R7_____________470R
@ 20°C n.t.c. Thermistor (See Notes) 1/4W Resistor (See Notes) 1/4W Resistor 1/4W Resistor 1/2W Trimmer Cermet or Carbon 1/4W Resistor (Optional, see Notes) 1/2W Trimmer Cermet or Carbon (Optional, see Notes)
C1_____________100µF
25V Electrolytic Capacitor
D1______________LED
(Optional, any shape and color, see Notes)
Q1____________BC547 Q2____________BD140
45V 100mA NPN Transistor 80V 1.5A PNP Transistor
M1____________Fan Motor 12V 700mA max.
Comments: Requested by some correspondents, this simple design allows an accurate speed control of 12V dc fan motors, proportional to temperature. A n.t.c. Thermistor (R1) is used as temperature sensor, driving two directly coupled complementary transistors wired in a dc feedback circuit.
An optional circuitry was added to remotely monitor fan operation and to allow some sort of rough speed indication by means of the increasing brightness of a LED. Notes: • • •
R5 must be set to allow motor just starting at the desired temperature. Any n.t.c. Thermistor in the 6K8 - 22K range value might work, provided R2 value is one/tenth of Thermistor's value. R6, R7 and D1 are optional: R7 must be adjusted until the LED glows faintly when the motor is just running.
Having Questions?
Parts: R1______________15K R2_______________1K5 R3_______________1K R4_____________270R R5______________22K R6_____________680R R7_____________470R
@ 20°C n.t.c. Thermistor (See Notes) 1/4W Resistor (See Notes) 1/4W Resistor 1/4W Resistor 1/2W Trimmer Cermet or Carbon 1/4W Resistor (Optional, see Notes) 1/2W Trimmer Cermet or Carbon (Optional, see Notes)
C1_____________100µF
25V Electrolytic Capacitor
D1______________LED
(Optional, any shape and color, see Notes)
Q1____________BC547 Q2____________BD140
45V 100mA NPN Transistor 80V 1.5A PNP Transistor
M1____________Fan Motor 12V 700mA max.
Comments: Requested by some correspondents, this simple design allows an accurate speed control of 12V dc fan motors, proportional to temperature. A n.t.c. Thermistor (R1) is used as temperature sensor, driving two directly coupled complementary transistors wired in a dc feedback circuit.
An optional circuitry was added to remotely monitor fan operation and to allow some sort of rough speed indication by means of the increasing brightness of a LED. Notes: • • •
R5 must be set to allow motor just starting at the desired temperature. Any n.t.c. Thermistor in the 6K8 - 22K range value might work, provided R2 value is one/tenth of Thermistor's value. R6, R7 and D1 are optional: R7 must be adjusted until the LED glows faintly when the motor is just running.
Having Questions?
Related Documents
Temperature
November 2019 25
Temperature
May 2020 14
Temperature
April 2020 25
Temperature Controllers
December 2019 30
Temperature Graph
May 2020 12