230VAC Temperature Fan Control

This is a 230VAC Temperature Fan Control circuit. This circuit is used for 230Vac operation. The R9 can be changed to 15K 2W, if the AC operation is 115V. This circuit uses the principle of Wheatstone bridge. The Wheatstone bridge is made from R3-R4 and R1-P1. P1-R1 produce a temperature-sensitive “variable” voltage and a fixed two-thirds-supply “reference” voltage is produced […]

Read more

Thermoelectric Heat Pump for Laser Diodes Stabilization

Usually, semiconductor laser diodes are operated from current drives. Unfortunately, The output power is strongly dependent on the device temperature – a rise of 15° causes a fall in optical power of (typically) 17% for a given current. Using a feedback loop and monitor the output beam intensity using photodiode is one method to stabilizing the operating condition. Not an […]

Read more

AD596/597 Setpoint Control for Temperature Controller

This is a setpoint controller circuit using The AD596/AD597. The thermocouple voltage is amplified, compared to an external setpoint voltage, and cold junction compensated. The device temperature can be monitored if the temperature to be controlled is within the operating range (–55°C to +125°C) of the device. Here is the schematic diagram of the circuit: Setpoint Voltage of AD597 is  […]

Read more

Analog Fan Speed Control

The large issue today that caused by more electronic equipment enters the home and the office is noise of fan. to reduce fan noise, a variable speed fan is used because it permits quieter and slower, fan speed when temperature conditions allow. To build a variable speed fan we can use digital control or high-speed/low-speed switches. Digitally controlled fans perform […]

Read more

Circuit Converts PWM Fan Drive to Linear and Reduces Acoustic Noise

We usually use a fan to manage the temperature, but it produces audible noise at full speed. To reduce this noise we can use this circuit. The first circuit reduces the noise by controlling the cooling-fan speed as a function of temperature. It uses an IC that combines temperature sensing with a PWM output. When the temperature of the processor […]

Read more

Linear TEC (Thermo Electric Cooler) Driver

Thermoelectric cooler (TEC) or Peltier cooler is becoming popular because of its robustness and maintenance free characteristic. Here is one example of a linear thermoelectric cooler (TEC) driver circuit. This driver  is capable of delivering ±2A into a TEC. This circuit operates on a single +5V supply and drives the TEC in the most preferred “constant-current” mode. Here is the […]

Read more
1 2