Temperature Controller for Crystal Oven

The temperature of a quartz crystal for oscillator should to be kept constant to operate at very stable frequency. This oven temperature controller is suitable for such purpose.  Here is the schematic diagram of the temperature control circuit: Although this circuit is small and simple, the design use a PWM output to preserve the efficiency.  The circuit uses LM335 temperature […]

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Fan Control Circuit Using LM56 IC

LM56 is a monolithic  thermostat designed for simple temperature control. The chip has two programmable threshold that can be used to drive a fan and or alarm.  Here is the schematic diagram of the fan control circuit: The circuit will turn on the fan when the temperature rise above 50 Celsius degree, and this threshold is set by the voltage […]

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Single Chip Thermocouple 4-20mA Current Loop Transmiter Circuit

Thermocouples give many benefits compared to thermistor/RTD (Resistance Temperature Devices).  Some advantages of thermocouple are their wider temperature range, their reliability, and their consistency over long period of time. In some cases,  thermocouple calibration  is even unnecessary. Thermocouple temperature sensors are widely used in temperature controllers for boilers, oven,  pressurized reactor, even in high temperature furnace. A general purpose temperature […]

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