Small surge protector using delay system by C1815

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.

Small surge protector using delay system by C1815

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
VR1___220K Trimpot
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.

This Post Has 5 Comments

  1. Dear sir ,
    please simple send me complete ATS (atumatic telephone line siwitch )circuit diagram ,

  2. dear sir,
    can you make another circuit like this: “Small surge protector using delay system by C1815”
    but instead of short time delay, can make delay about 1 minute. can please use DC24V relay.

  3. Hello, Gari Dizon
    Thanks for your question. This circuit is suitable for adapting to DC24V.
    You may try to change the voltage of the transformer is 18V AC. When it changes to DC is 25VDC. It can use for 24V relay. Others parts you can use 2 times for original. such as VR1 changes to 500K, C2 into 220uF 50V.
    DO NOT forget use C1 = 1000uF 50V only. If you use only 25V! It will break the C1 boom!!

    If you want to test others circuits: It may be a good choice for you. The MOSFET is easier than the transistor and can use with 24V too.

    I hope you are happy with your project. Please come back to share me.

  4. hello sir,
    thank you.
    i am researching for a protection circuit for machine, example is during sudden power interruption/fluctuation, our machine AC220V component is broken all the time.
    we know sudden power fluctuation is very fast
    i am looking for a power failure protection circuit for AC220V, that during power failure/fluctuation it will
    shut down the machine permanently very fast at the moment then when normal power resumes, the circuit will be reset manually by a person. do you have this kind of circuit? AC200V power or AC220V to DC24V i need.
    Thank You

    1. Hi, Gari Dizon
      Wow! Are you making a large project? I never make a big project. Because the project requires times and money too much.
      My kids take my time.

      This circuit can slowly turn on the load when power outage.

      Another circuit may be the project protects a power motor:

      Do you need the 24V power supply?
      It is a linear power supply. Easy to make. But I not sure when you use all time run 24hour. Can It bear for your job?

      Have a good day.

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