Power failure, voltage drop, power surge, but do not worry when has this circuit.
Sometimes when raining and may be windy, until a power failure and the power lower or a flashing lights switch in a short period. And causes the power surges severe. until may cause the electrical, such as TV, refrigerator, computer or other damage.
Which is normally protected by the appliance is turned off. But maybe the power failure period, In a different time, Cause you to lose time to stand to turn on – off more often.
As has electronics in the heart, Cannot ignore this problem.
We should have a system time delay. When a power failure, Then, not long typical power. This system is not connected to the AC line to the electrical appliances. But it will time delay is period of time, when the surge electrical away, power system will continue to electrical appliances again. Our electrical appliances so safe. Without the worries. this surge protector circuit build simple and cheap as ever.
How this circuit works
At first, not have a 220 volt AC power into this circuit, The relay contacts-RY1 are connected to NC terminals. As shown in a circuit figure below. Thus making electrical appliances is not working. But after the powering the primary coil of the transformer T1 and then the secondary coil has AC voltage is 9 Volt, next it is So is rectified from AC to DCV by diodes D1-D4 and is filtered voltage with smooth by C1.
These parts are VR1, R1and R2 helps to divide the voltage to bias current to transistor Q1. But it was not until …
How to delays?
The C2 as acts the delay, by it will store slowly charged, until enough to Q1 works. The VR1 is used to adjust the time delay. (Time delay is electrical appliances, do not run immediately, After the AC line flowing into this circuit.) when Q1 and Q2 transistors works. Contacts of the relay is switched to the NO. electrical appliances are ready to works now. In the event of a power failure the relay contact is connected to the NC, RY1a cut off electrical appliances out of ac line power. For the D5 to protect the transistor from the operation of relay.
The parts of this circuit
Q1_____NIO = The transistor number are 2SC458 or 2SC828 or 2SC945 or 2SC1815 or other NPN transistor small size.
Q2_____2SC1061 or BD139 or TIP31____NPN medium transistor size
R1_____220K 1/4W Resistor
R2_____68K 1/4W Resistor
D1-D5__OID is diode 1A 50V to 1A 1,000V__No.1N4001,1N4002 to 1N4007
C1_____470uF 25V____Electrolytic Capacitors.
C2_____100uF 25V____ Electrolytic Capacitors
RY1___Relay 9V coil , contact 3A 250V
T1_____Transformer 0.5A 9V
How to makes
This project is easy to make so contain all parts into the perforated board that small size.
I know that you can build them for beginners. But you should always fine and be careful in check circuit diagram always before you insert ac line onto this circuit.
I hope you to enjoy this project.