Posts Tagged ‘Temperature Switch’



Heating System Thermostat

Sunday, March 30th, 2008

Controlled by indoor and outdoor temperature Simple, high reliability design This circuit is intended to control a heating system or central heating plan, keeping constant indoor temperature in spite of wide range changes in the outdoor one. Two sensors are needed: one placed outdoors, in order to sense the external temperature; the other placed on [...]

Temperature controlled Fan 12V dc

Monday, January 28th, 2008

Suitable for computer cooling fans LED motor speed indicator 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 [...]

Frost Alarm or Cold Activated Switch by IC 741

Friday, June 1st, 2007

A simple thermistor triggered cold switch with adjustable threshold. The thermistor used has a resistance of 15k at 25 degrees and 45k at 0 degrees Celsius. A suitable bead type thermistor can be found in the Maplin catalogue. The 100k pot allows this circuit to trigger over a wide range of temperatures.If using a different [...]