ITTSB.EU Blog Forum
Electrical Applications | Basic Power Analysis | Accessories | PSU | UPS evaluation | Battery analysis | CCTV camera system troubleshooting => Power supply / Battery Chargers => Topic started by: giorgos on December 27, 2013, 07:00:27 PM
-
I am starting this topic, in the occasion of a project, that I found in an old Elektor magazine (early 90s).
We know that there are plenty of DC regulated power supplies in market, or as schematic projects for DIY.
What about AC? The first answer is to use a variac in order to have an adjustable AC voltage source.
The point here is that "ok we have adjustable AC voltage here, But what could we do ,If we want this voltage to be regulated (indepented from load changes)?
In market there are some specialised AC power supplies but their cost is unapproachable for a common technician.
So this circuit comes to give an alternative solution with minimal cost. In any case it can not be compared with a professional AC supply ,but it will be found useful in many cases.
I will not enter in circuit analysis here, the only critical point in this circuit, is the "hand made"optocoupler, consists of two 3mm LED and a photoresistor, included both in a small box.
I am going to make this circuit as I am curius to test it. I have already made the pcb and now I have to concentrate the components to assemble them.
I didnt copy Elektor pcb because i found it a little big, with a rather big unsued area of the board.
I used for it, sprint layout software.
So it remains to integrate this project to share my conclusions.
-
For just adjustable AC voltage measurements I am driving with my function generator one 220V/6V transformer from the 6V side of it.
But it is a secret ... LOL
If you get from it about 110W at 220V it would be nice. :)
-
Your generator must have very powerful output stage to drive a transformer! Im sure about that as i have seen your philips generator in other post, and really is a great instrument.
Regarding the circuit that I posted, I think that is an alternative approach. Also I forgot to mention that it can supply Ac voltage from 0 to 25 V and maximum current 1 A according Elektor.
-
Regarding the function generator and the transformer all that is needed, is to overcome the operating current of the transformer with out any load, and yes this old Philips it can handle it. ;)
Even as 25V AC at 1A looks good enough, in most cases you will use just 10AC with a rectifier bridge (12DC), so you can possibly even get a bit more current as 1,5A from it. ;)