AC on breadBoard

[Paula]

Dear Experts,

I am Paula and I have a general electronic question. Can I use AC Current on breadboard? The current should not exceed 2A. I have a small circuit which I need to test before design PCB.

Paula

[Mike Walne]

Yes and no.

Depends on what you intend doing with the AC.

Please elaborate.

Mike

[Paula]

Thanks for your reply. Infact i would like to build a small transformerless powersupply to driver a small circuit which includes a relay.

[Mike Walne]

Yes it's possible

I must warn you. Without experience, potentially LETHAL.

This is CCS 'C' compiler forum.
I'm assuming you intend including a PIC on your board.

Mike

I'm also assuming you intend to use live mains.
And I mean lethal for the PIC & YOU.

[SherpaDoug]

AC or DC makes no difference. But if the voltages get dangerous, above 24V or 48V, think about the consequences of a wire coming loose.

For high voltages you are really better off soldering wires or using some other very secure method.
_________________
The search for better is endless. Instead simply find very good and get the job done.

[temtronic]

You can put 2 amps though a 'solderless breadboard', but 'double up' the conductors in the 'pin holes'! It'll reduce the chance of 'meltdown' due to high resistance of a single conductor. Yes, I've melted breadboards before.
Main concern, after high voltages /currents is noise to the PIC. Assuming you're building a SMPS type circuit,any kind of 'stray noise' could be disasterous for the PIC. You might run into 'program' problems caused by erratic resets, bad data in RAM,etc. None of which is really the code or programs fault. No amount of second guessing why the code is acting 'funny' or trying suggestions from here will really help if the basic hardware is faulty.
I know this thread is a bit off topic, but we could spend hours trying to find the 'bug' in your code when there is none, just a bad ground or other hardware issue.
I have to admit I try all my circuits/code on breadboards. If it runs at 64MHz, it'll work on perfboard or a real PCB, reducing the 'real' problems to my coding skills.


hth
jay

[Mike Walne]

Still on the assumption that you're intending working directly on live mains with a transformerless converter.

How are you going to SAFELY probe your circuit?

You need to tell us a lot more about what you are trying to do.
There are now several of us warning you about the dangers.
It is done in commercially available products.
My home central heating controller uses a cap dropper power supply and includes two 24V coil relays.

Mike

[Ttelmah]

Would you understand what I meant if I said to 'put one hand in your pocket', and why I say it?.
If not, then you are not safe to even start to think about this design.
You should go and do a basic 'working with high voltage' safety course _first_ otherwise you risk killing yourself (or somebody else).

Best Wishes

[SherpaDoug]

If you are working with line voltage and you don't have one I STRONGLY suggest you invest in an isolation transformer like one of these on ebay:
271181561888 or 390571257004

Not everything listed on ebay as an isolation transformer is really an isolation transformer. In a pinch at low power you can use two bell transformers. One to go from line voltage to say 12V and another used backwards to go from 12V back up to line voltage. But the losses add up and the resulting isolated line voltage is not very stable.

With care an isolation transformer can save a lot of accidental damage. Without care you are doomed anyway.
_________________
The search for better is endless. Instead simply find very good and get the job done.

[Paula]

Dear all,

Thanks for your reply. In fact the reason I'm going to use transformerless power supply for my circuit is that i need to fit my circuit in a 3x3 box and there is no room for transformer. And since the load is very small, i thought that transformerless power supply is ideal.

[Ttelmah]

3x3 what?. Inches?. cm?. mm?. The last time I used transformer-less, the entire circuit had to go into a volume less than 0.5cc. It was actually built into the plastic of a mains plug.
Small transformers are readily available, and a _lot_ safer. Off the shelf transformers about 3cm*3cm*1.5cm are readily available.

Best Wishes

[Paula]

If i am not mistaken, i already said that it will be an electrical project. 3x3 is the british standard wall box. Sorry i assumed that everybody is aware. Sorry i took it for granted! In fact as you said Ttelmah this will be a kind of project similar to yours. Can you send me some photos if you have to have an idea of the design? Really appreciated.

[bkamen]

[ezflyr]

Hi Paula,

Just to steer the thread back "on topic", which PIC are you using, and what is your compiler version ?

John

[Mike Walne]

You're still telling us very little about exactly what you're trying to do.

1) Student/hobby project, commercial product?
2) PIC?
3) Compiler version?
4) Inputs / Outputs?
5) Where does the 2A appear?
6) Could you use an isolated power supply?
7) Your experience?

We're not trying to discourage you from using PICs.
We're all concerned that without experience, working on live mains is very dangerous.


Mike