Home  |  Circuit diagrams  |  Electronics projects  |  Store  |  Links  |  Contact  |  Privacy policy  |  Sitemap

..::::..





On-Off Temperature Control

On-Off Temperature Control

This circuit controls a load (in this case a dc brushless fan) based on a temperature compared with a setpoint. THe transduced is a diode in the forward polarization regime. In fact when forward biased, the forward voltage drop accross a diode has a temperature dependance, in particular has a negative linear(ish) slope. This because of the boltzmann distribuition, causing electrons to pass to the conduction band thermically, lowering the voltage drop accross the diode.
Anyway this circuit comparates a precise voltage reference (zener) with the forward voltage drop of the diode forward biased with 11mA of current.
The comparator is simply a LM158/258/358 working in open-loop mode, the inverting input is connected to the diode sensor, and the noninverting to the reference voltage. Se when the temperature rises above the setpoint, the forward voltage drops under the voltage reference and the comparator output is vccturning on the transistor and so the fan.
Higher power transistor can be substituted for bigger fans, or you can substitute a relay, IGBT, mosfet etc to control higher loads (and higher voltages).
The setpoint is adjusted with the potentiometer, and you can use a LM3914 led driver to make a temperature setpoint indicator (needs careful calibrations and the use of excel to calculate slope and intercept).
Many modifications can be done, but the circuit works very well in its basic form.
THe comparator can distinguish 10uV differences so approx 0.01°C differences (carefully adjusting the potentiometer can allow to feel body heat from 1/2 cm from the sensor, or feel ambient heat, making to turn the fan on and off continuosly)
You can control temperatures up to 140°C (150 max diode temperature), but linearity is not ensured
Possible uses? Heatsink cooling, computer emergency cooling (but i thint that a linear device would be better than a on-off) metal cooling when drilling etc...
Ah! One note: you can even heat with this circuit but you need the reverse comparator inputs and substitute the fan with a relay controlling the heater.

Source: Electronics Lab

..:: Important ::..

Read disclamer, please!

 

Circuit diagrams home  |  Circuit diagrams  |  Electronics projects  |  Store  |  Links  |  Privacy policy  |  Contact


Cialis 5 mg senza ricetta Effetti collaterali del Cialis 5 mg Ordina Cialis 20mg Consegna a domicilio di Cialis originale in Svizzera Acquista Viagra in Svizzera senza prescrizione Cialis 10mg senza ricetta Dove comprare Viagra in farmacia online Sconto Cialis 5mg Dónde adquirir Reduslim Spedra Avanafil in vendita online Acquista Viagra in Svizzera senza prescrizione Dónde comprar Cialis Comprar Viagra Contrareembolso Descuento Cialis 5 mg Comprar viagra original Efectos secundarios de Cialis 5 mg Reduslim resultados Remedios para la Disfuncion Erectil Cilis vs Viagra Aviator ???? ?? ?????? Acquisto Cialis 5 mg online Cialis 5 mg effetti collaterali Comprare Cialis 20mg a buon prezzo Consegna a domicilio di Cialis originale in Svizzera Acquisto online di Viagra senza ricetta in Svizzera Cialis 10mg Acquistare Viagra in farmacia online Costo del Cialis 5mg Reduslim opiniones Comprare Spedra Avanafil senza ricetta online Dove comprare il Viagra in Svizzera Comprar Cialis barato precio Viagra genérico Descuento Cialis 5 mg Viagra sin receta Cialis 5 mg efectos secundarios severos Reduslim pérdida de peso Problemas de erección tadalafilo en venta avanafil prezzo cialis 20 mg prezzo cialis effetti benefici cialis 10 mg Reduslim Kaufen pulse x coin price avanafil prezzo buy cialis or generic tadalafil ?????? ?????? ??????????? ?????? ???????? ?????? ?????? ????????? ?????? ?????? ???????????? ?????? ?????? ? ?????? ??????????? http://diplomy-originaly.com ?????? ?????? ????? ?????? ?????? ? ??????? ??????????? ?????? ?????? ???????? ?????? ?????? ???????????? ?????? ?????? ???????????? http://diplomsagroups.com ?????? ?????? ????????? ??? ?????? ?????? ?????? ?????? ????????? ???? ?????? ?????? ? ??????? ??????????? ?????? ???????? http://sreestrom.ru/ ?????? ???????? ?? 11 ????? ?????? ?????? ?????????? ?????? ?????? ???? ?????? ?????? ? ???????? ?????? ?????? ? ?????? ??????????? https://russian-diplom.com ?????? ?????? ????????? ? ?????????? ? ?????? ?????? ?????? ???????????? http://rudiplomirovanie.com ?????? ?????? ? ??????? ?? ? ?????? ?????? ?????? ???? ?????? ?????? ???????? ?????? ?????? ? ??????? ?? ? ?????? ?????? ???????? https://premiums-diploms.com ?????? ?????? ? ???????? ?????? ?????? ????? http://russdiplomiki.com ?????? ?????? ????? ? ?????????? ? ?????? ?????? ?????? ??????????? https://diplomansy.com ?????? ?????? ? ?????????? ? ?????? ?????? ?????? ?????? ???? https://diploms-asx.com ?????? ?????? ? ?????????? ? ?????? ?????? ?????? ?????? ? ??????? ??????????? ?????? ?????? ????????? ???? ?????? ?????? ? ?????????? ? ?????? ???? ?????? ?????? ? ??????? ??????????? https://eonline-diploms.com ?????? ?????? ????????? ? ?????????? ? ?????? ?????? ????????????? ? ???????? http://free-diplommi.com ?????? ????????? ?????? ?????? ?????? ????????????? ? ???????? http://diplomrussian.com ?????? ?????? ?????????? ?????? ?????? ?????? ? ?????? ??????????? ?????? ?????? ???????????? ?????? ?????? ???? ? ?????????? ? ?????? ?????? ?????? ????????? ?????? ?????? ???????? ?????? ?????? ???? ? ?????????? ? ?????? ?????? ?????? ???????? ?????? ?????? ?????? ?????? ? ?????????? ? ?????? ???? ?????? ?????? ???????? ?????? ???????? ?????? ?????? ????????? ? ?????????? ? ?????? ?????? ????????????? ? ????? ?????? ?????? ????? ?????? ?????? ????????? ? ?????????? ? ?????? ?????? ?????? ? ?????? https://diplomsy-landsy24.ru/ ?????? ?????? ???? ? ?????????? ? ?????? ??? ?????? ?????? http://diploms-service.com ?????? ?????? ????????? ? ?????????? ? ?????? ?????? ?????? ???????????? https://kyc-diplom.com ?????? ??????????? ?????? ? ?????????? ? ?????? ?????? ?????? ???????????? ??? ?????? ?????? ?????? ?????? ? ???????? ??? ?????? ???????? https://originaly-dokuments.com ?????? ?????? ? ?????????? ? ?????? ?????? ?????? ?????? ???? https://diplomy-grup24.com/ ?????? ?????? ? ?????????? ? ?????? ???? ?????? ?????? ??????????? ?????? ?????? ????????? ?????? ?????? ???????? ?????? ?????? ?????? ?????????? https://diplomansy.com/kupit-diplom-novogo-obrazca?????? ?????? ? ????????? ? ?????? ?????? ?????? ????????? ???? ?????? ?????? ? ?????? ????????? ?????? ?????? ? ???????? ???? ?????? ?????? ???? https://diploms-asx.com/kupit-diplom-magistra ?????? ?????? ? ?????????? ? ?????? ??????