Help identifying gear please

[sonolink]

From the datasheet, 100mA max across the unit (ie both channels putting out +22dB into 300 Ohms). In my builds I tend to use 2x15V / 30VA toroids paired with a Silent Arts FP48PSU board, if that helps, though that's with relays and LEDs and such as well.

You wire those in series to get 30vac and then regulate down to 24vdc with a 7824 kinda thing?

On a side note, I was intrigued by your note about a bipolar V372 above. Having worked on a few TAB V372 modules, I've never seen one with a negative power rail - as with most (all?) German broadcast modules I've seen, they were all +24V. Can you share a link? Thanks!

Of course.
Tab V372D schem attached

 

[TwentyTrees]

You wire those in series to get 30vac and then regulate down to 24vdc with a 7824 kinda thing?

Yep, spot on. But as I say, I'm powering other things as well so best thing to do is calculate what you'll need and size accordingly.

Tab V372D schem attached

Thanks! Every day's a school day.

 

[sonolink]

I have modified a bipolar PSU designed by Rochey to serve as +24v and phantom power source. Could you take a peak and see if there's anything blatantly wrong please?

 

[sonolink]

Nobody? Pretty please?

 

[mad.ax]

Look at your schematic and ask yourself what happens when the two left diodes of BR1 conduct?

 

[sonolink]

Oooops. Thanks for pointing that out....is this more like it?

 

[mad.ax]

This one shouldn't smoke ...
But you should have a look at the circuit that TwentyTrees proposed...
http://www.silentarts.de/Techtalk-Laden/FP48PSU_rev02-Doku.pdf

 

[sonolink]

This one shouldn't smoke ...
But you should have a look at the circuit that TwentyTrees proposed...
http://www.silentarts.de/Techtalk-Laden/FP48PSU_rev02-Doku.pdf

Looks cool circuit. If using a 2x15v secondary in series I would get 30v at "POS" adjustable down to 24vdc using RV1 and IC3 determines what you get at "FIX" (I guess to be used with switches/relays)?

 

[mad.ax]

Using 2X15V in series, you'll get 30V AC at the AC input of the rectifier, aka 36V DC under load at the input of the regulator... That's allready the maximum for some 7812 should you use one of those for the FIX output!
Now, if your wall voltage goes up +10%, you'll reach the 40V max input limit of the LM317...

You'd better use a 2X12V secondary.

 

[sonolink]

Mmm I mentioned the 2x15 because Twenty Trees said he used that trafo with that same circuit.... maybe he uses 24v relays to avoid heat?

Probably it's best to use a 24v sec but just out of curiosity maybe you can share what you do Twenty Trees?

 

[TwentyTrees]

24v relays

Yep. And, on my builds, some other bits and bobs that needed slightly higher voltage. But 2 x 12V would be spot on for the basic 24VDC.

 

[sonolink]

Yep. And, on my builds, some other bits and bobs that needed slightly higher voltage. But 2 x 12V would be spot on for the basic 24VDC.

But you use 2x15v with Volker's PSU don't you? I'd be interested in how you use them together because I have a Triad Magnetics 2x15v/30VA on a shelf that I could use for this and if it works that would spare me the cost of getting a 2x12v...

 

[TwentyTrees]

It'll work fine, just means you're ideally looking at 24VDC for the "fix" utility rail. Make sure to use beefy heatsinks on your regulators, and test your voltages before you plug in the V472. As mad.ax notes, 2x12VAC would be a better bet if you don't need higher voltages.

I will note that it looks like your V472 has been recapped - that vintage of V472 comes with the red Roederstein electrolytics I believe, whereas on your photo they appear to be more modern ones. That's likely helpful and will save you a job.

 

[sonolink]

Ok I'll use the toroid I have for this one then
I'll probably be back asking for more help after I build the PSU

Thanks a lot to all for your time and help
Cheers
Sono


!

 

[TwentyTrees]

Good luck with your build!

 

[sonolink]

Hi guys!! (Told you I'd be back soon hehe)

Do you reckon this transformer would be enough for this unit, using Volker's PSU and including relays, phantom power, pad LED and a power on/off LED?

https://www.musikding.de/Toroidal-transformer-230V-2x-12V-10W
Cheers
Sono

 

[mad.ax]

Largely enough for a couple preamps with relays, LEDs, and phantom...

 

[sonolink]

Excellent!! Thanks!!

 

[sonolink]

One last question about trafos PLEASE: do you reckon this is a good idea considering the price?

https://es.aliexpress.com/item/3288...b0a119a16547084145713495e9f70!65757896359!sea

 

[mad.ax]

Seems to be a switching PSU rather than a transformer... At this price, it might be a bit too noisy for audio.