tda2050 power supply

[scaesic]

i want to build an amp with a split supply +/-15 to power a mosfet boost, eq section and tda2050.

how do i work out my current consumption requirements? and how do i figure out what type of power supply schematic to use, bridge rectifier, capacitors and transformer to use?

id be running the mosfet boost on 0-15v, and the eq/tda on the full split +/-15v

should i use one of those regulator chips too?

[petemoore]

http://geofex.com/Article_Folders/Power-supplies/powersup.htm
  Thanks for the link and the article again RG !
  i want to build an amp with a split supply +/-15 to power a mosfet boost, eq section and tda2050.
how do i work out my current consumption requirements? and how do i figure out what type of power supply schematic to use, bridge rectifier, capacitors and transformer to use?

id be running the mosfet boost on 0-15v, and the eq/tda on the full split +/-15v

should i use one of those regulator chips too?
   I didn't, and let someone else chime in ..other than I don't think PS noise is an issue with good coupling caps and no regulator...of course the regulator will hold the supply voltage very steady when AC wall voltage 'moves [up to a point].
  Separate shielding for the preamp and amp did seem to be an issue, I had a preamp booster and amp in box and it was noisy.
   

[petemoore]

  I'm about to test how queit a power supply without the regulator I don't have here on one of the 8 Spyder outputs.
  I do have many 1n400x diodes and built a diode bridge and 220uf smoothing cap on it, the 11vac converted to 15+ vdc...which I'm thinking might be a nice voltage for a simple mosfet gain stage I have...I may have to turn a bias trimpot, then I can see how the the noise performance' is.
  It'll be easier to tell when I get some of the outputs regulated, then I can try reg/unreg quickly by choosing outputs.

[soulsonic]

I highly recommend using a regulator between the preamp and the TDA2050 - it will do much to keep the poweramp's high current noises from infecting the preamp. An LM317 is an excellent choice (very low noise) and should have no problem delivering the current required for the preamp.

As far as overall current is concerned, it depends on how much power you want to be able to put out. I would consider running it on a higher voltage - probably something closer to 20-ish volts. You can start with a transformer with a secondary of about 15VAC at around 2 Amps. The unregulated voltage after the rectifier should be around 20 volts or so. This should be able to give you about 15watts of clean-ish power.

So I recommend running the TDA at +/-20V and then use the regulator to do the rest at +15v.

[trevize]

I would use an unregulated power supply. For a 2050 I would say a transformer with a 70VA 17-0-17 secondary; a diode bridge and four 35v 3300or2200µF.
Don't forget a sloblow fuse too.

[George Giblet]

> 70VA 17-0-17 secondary

The absolute maximum DC rail for the amp is 25V.  If you factor in transformer regulation (load and mains) you wouldn't want anymore than 15-0-15 on the secondary.   A 12-0-12 isn't pushing the amp so hard but the output power is less.

VA rating will depend on 8ohm or 4ohm load.  The required heatsinking will de determined on the final supply voltage and load impedance.

[scaesic]

i want the amp to run clean, im not planning on pushing the power amp section, but i am using the 2050 in order to get more headroom.

i intend to have an 8 ohm output, but i want to have a speaker out to drive other cabs with the amp.

to clarify more specifically: i just build an unregulated supply with a transformer to give +/-20v to the power amp (taken from rg's article?) and then i can use one of those regulator chips to power the eq and preamp at +/-15v?

will this give me low enough noise? also, is there any articles about figuring out what kind of transformers to use? it has to be pretty physically small in order to fit the chasis.

what parts from these pictures can i salvage? (unfortunatly the transformer doesnt have any information that seems useful)