Need a place to start...

Hi,

I need to come up with a circuit to generate alternating currents. (Range 0-5A sinusoidal) It needs to be controlled through a user interface in the computer. I'm clueless guys. Plz help...
Give me a place where can start. I should admit that I'm a NOOB

Anybody have any idea??

I have got three suggestions so far...
1). Using a triac with a PIC to control its firing angle...
2). Generate PWM and drive a half bridge with IGBT's...
3). Use an audio amplifier controlled by audio signal source...

I don't have an in-depth knowledge about any of these designs. Can anybody please comment on these... I'm kinda lost

Can you give us an idea of what frequency and voltage ranges you want in addition to the 0-5A capability?

1). Using a triac with a PIC to control its firing angle...

Click to expand...

This will give you a fixed output frequency and not a very nice sinewave at all.

2). Generate PWM and drive a half bridge with IGBT's...

Click to expand...

This will do what you want, but is somewhat complicated for a noob.

3). Use an audio amplifier controlled by audio signal source...

Click to expand...

This is will also work over a limited frequency range determined by the audio amp's frequency response.
You could use something like this with the audio amp:
**broken link removed**

Hi kchriste,

Thanks a lot for the reply. This is going to be used to test relays, i.e. apply a specified current and measure the tripping time. I don't have a clear idea about the voltage I have to generate a 50Hz sine wave of specified current ranging (0 - 5A)

I decided to take the amplifier option. So I guess the basic block diagram should be like this...

**broken link removed**

I still don't have an in-depth knowledge about the design.

I searched a bit and came up with a signal source. Hope I'll be able to use this...

Please add comments... Will it be easy to follow the design with IGBT??

hi,
If its 50Hz and sinusoidal, why not use a Variac Transformer to drive a 1:1 isolation transformer [ thats if the isolation is required] ?

The voltage isnt specified, so taking the worst case as mains ie; 250Vac then
250 * 5 = 1.25KVA rating for both transformers.

You can get motorised Variacs that the PIC/driver can control.

Yes I agree, but It's better to have the isolation transformer as at low voltages the current will be 'lost' magnetising the isolation transformer,