Power Supply Build

  • Thread starter Thread starter James K
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J

James K

Member
Hi,
I'm preparing to build a power supply to power various bits of studio equipment (mic pres, EQs etc.) It needs to supply +-18V to power the units themselves and +48V for phantom power. I've sketched out a schematic for the unit. I would very much appreciate it if anyone could tell me if this design is suitable and any problems there are with it. (The mains wiring has been deliberately omitted.
power supply.webp


Cheers
James
 
That will work but I would maybe add another smaller cap after the regulator on the 7918/7818 ......

You don"t really need the 40v winding for the phantom power , Since Phantom power even for several channels is still not a large current draw you could use a Voltage tripler on the 15v AC winding and use the same TL783 regulator setup ...... Ive used a Tripler many times with good results and it saves you from having to find a Transformer with 2 seperate windings .....

Cheers
 
Hi,

Remember them 78xx and 79xx can only deliver 1 amp max... Also, you should decouple the in/out pins to the ground (100nF or so) verrry close to the chip.

Check Gyraf's G9 schematic for a rock solid +48V based on a tripler!

Paul
 
Have you simmed the raw supply in PSUDII under the expected load? You need to check that the raw supply will cover the necessary output-input minimum voltage of the regulators. If not, you'll need a higher voltage transformer and appropriate heatsinking.

You might also consider using adjustable regs like the LT units- slightly higher parts count, but significantly better performance. And the supply performance will be critically dependent on layout and grounding.
 
FYI: for the 18v, PAIA sells a bipolar kit for about $15 or so. I also (thought) I needed one quick bought a completed unit off ebay for about $20, (that was +/- 15, the same seller sells bare PCB's for about $8 or so, and I think the bare PCB for a higher voltage version is around $12 or the complete unit is about $40, (not including transformer) Edcor should have a dual primary trafo that would work for your phantom power circuit. Shipping from the US or China shouldn't be too prohibitive for anything but the transformers, you can probably find something suitable from Canford maybe or some of the DIY type shops in Germany.

Here is a mosfet psu: and I believe the PCB is 12 Euros.

http://www.loetstelle.net/projekte/mosfetpsv2/mosfetpsv2.php

http://www.askjanfirst.com/dindex.htm?/loetstelle.htm

A previous version in English:

http://www.solderingpoint.com/projects/mosfetps/mosfetps.php
 
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