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I am doing a project for my university. It is about multi power outlet with timing interval between each power outlet which uses micros processor and some more features.

I don't know much..im still researching about the project.

I was just wondering if i have say 8 power outlets, can i have reset switches for each of the 8 outlets? (Assuming all running at 230V for example dvd, amplifier, plasma and so on)

Reason for reset switches: so that when one of the power outlet is reset, the AC power in the other equipment connected has still power running without interruption.

does it make any sense :)
If anyone would like a bit more details specifications i have attached a copy of it in microsoft word document.

or any particular web sites or books i can look into for more info..
thanx a lot.

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Hi and welcome,
Your attachment doesn't show up, I tried once and it didn't work either.
It sounds like your project needs a circuit-breaker (disconnects when current is exceeded) with its own reset button, for each outlet.
It also sounds like you need these outlets to be powered sequentially when the power is first applied, in order to avoid a huge power-up current surge. (Do your lights dim when your computer is turned on? What would happen if you turned on 8 computers at the same time? Poof.).
So you need an electronic power switch and a current-measuring circuit, for each outlet, controlled by a micro-p.
A Triac is a good power switch device. Check the Articles section of this site for details. The gate signal for the triac can come from the micro-p. The current-measuring is done by simply wiring a low-value resistor in series with each outlet (ohms law, 10 amps through a 0.1 ohm resistor gives 1 volt). The voltage across each resistor feeds the micro-p. On each measurement when its power is first switched on or the outlet is reset, allow for a delay time in the micro-p. routine for the power-up surge to pass.
When power is first applied to the whole system then the micro-p. sequentially turns on each triac. If the measured current exceeds a certain amount then the micro-p. turns off the outlet's triac. Each reset button feeds the micro-p.
Note that the triac and current-measuring resistor are directly connected to the mains, so for safety the micro-p. must be completely insulated in a plastic box (don't hook-up your computer to the triacs nor the resistors) unless you use a complicated isolation method for the signals.
I hope this helps you to get started.

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Hi Groovy, welcome!

In a case like this I would use zero-cross optoisolator triac driver and current transformers to obtain maximum personnel safety and protection for the circuit. Another good reason for the zero-cross optoisolator triac driver is the

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Groovy, I would also like to offer another alternative. The circuit below could be duplicated for each control pin of the microprocessor and the relay controlling the 220V line. When you send a 0 to the microprocessor pin connected to the base of the transistor, the transistor is on.
Now you have a few choices.


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audioguru, the original request was for a way to switch the power with a microprocessor. That is the first message I see in this thread.
It was you and ante who went into a discussion of triacs. You might want to go back about 7 posts and read again.
You would rather groovy has limited options?
Again, I see nothing but argument from you.

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