CGS14 Power Supply Transformer Question

[LetterBeacon]

I'd like to build the CGS14 power supply to output +/-9V and I need to be able to pull 500ma from it.

Would this be an appropriate transformer to use?

It's 24V centre tapped @ 50VA. So 50 / 24V = 2.08 supply amps. If I use 7809 and 7909 regulators, I should be able to pull 500ma easily, right?

[andrewF]

It will do the job
please check the documentation, these transformers may be a different design to the norm. but usually it goes like this -

from the link, I think the taps are 0 V 0 V

So connect together the middle V 0
and that will be your 0V or CT

The outer 0 and V will connect to the AC inputs on the PCB, doesn't matter which way.
assuming your regulators are rated for 1A, sucking 500mA will be no worries, tho give the poor regs some heatsinks.

[LetterBeacon]

Thanks a lot!

[andrewF]

[LetterBeacon]

Unfortunately it looks like the CGS14 board is out of stock (you'd think I'd have checked that before I made this thread!) so I'm looking for alternatives I can build.

I've found the following schematic and stripboard layout from here:





This won't give me a bipolar output but I didn't really need it anyway.

The differences between this circuit and Ken's are the smaller filtering capacitor, the fact he uses 4x 1N4001s instead of 8x 1N4004s and the LEDs.

If I increase the 470uf cap to 2200uf (as per Ken's schematic), and swap the 1N4001s for 1N4004s then building it on a stripboard isn't going to cause any problems, right?

[andrewF]

If you don't need a +/- supply and want 9V, the cheapest easiest option is to get a 9V plugpak/wallwart.
junkshops usually have dozens of them for $1 or so.

[LetterBeacon]

I don't know, you'd be hard pushed finding a wallwart in London for that kind of money! I'm also keen to run this power supply from the same IEC socket as my current +/-15V supply (with the proper fusing and wiring, obviously) so I only have one plug coming from the modular's case.

I think I'm going to have a go at adapting this stripboard layout into Ken's power supply. It only really involves swapping the diodes for 1N4004s and adding a couple of extra ones.

Thanks a lot for your help!

[andrewF]

no worries

for this circuit 4001 diodes will be okay
the final number indicates the maximum voltage the diode can handle, for example:
4001 50V
4002 100V
4004 400V
4007 1000V

datasheet