Tuesday, January 24, 2012

Freeze Protector Circuit



This is the simple freeze protector circuit diagram. It is also called timing circuit. It is just hobby project for beginners. When you need to operate automatically any device in the fixed time later after coming AC power supply, you can use this circuit. 

The voltage amplitude is high when AC power come. Suddenly high voltage destroys the electronics device. For this reason, in the time of load shedding we need to switched off electronics device (Audio/Video player, CD/DVD Player, TV, Freeze or any electronics device). This circuit solve this problem.

Hobby Electronics helps the beginners to know the timing circuit specially using 555 IC timer. NE555 IC is the very simple well known parts. Its configuration is very simple. You can use this timer any simple circuit. 

In this circuit use 12volt power supplies. 300k variable resistor is used for timing control. Timing resistor and capacitor are 300k and 1000uF. Only change the value of the variable resistor for your required timing. 

The circuit output pin 3 is connected with resistor (10k) and output 12 volt relay. Relay is connected as figured with the device. Making cost is too low. Anyone can make this circuit easily.

Thursday, January 19, 2012

Dual Voltage Power Supply 12 Volt

This is the simple circuit diagram of Dual Voltage Power Supply. It is used for Misc… application. This circuit is called regulated power supply. For this reason the main component of this circuit is Regulator IC. It also needs few components to built. The regulator 7812 is the positive voltage regulator and  7912 is the negative voltage regulator. 
You can also use 7809 for 9 volt positive power supply and 7909 for negative voltage power supply. 

It regulates voltage from 24Volt to 12 Volt (DC). The transformer input is 110Volt to 220Volt (AC) and the output must be between 12Volt to 24Volt (AC) and current must be 500mA. In this circuit some capacitors are used as a filter for removing repole.