Power

[jflam]

Does anyone know if I can wire the ground (center tap) and negative dc output on a center-tapped 24v transformer.

[Peter Snowberg]

I don't quite understand the question. Could you add some details please?

Thanks,
-Peter

[jflam]

In the Anderton EPFM schemo for the Bi-polar power supply:

Can I connect the negative and ground wires together??? If I do that, should I ground the chasis as well??

I want to use dc jacks to connect my effects, not the three-pin Molex connectors he calls for. This will be possible to achieve if I can do the above, correct?

[Lonestarjohnny]

I think I understand what your asking, First, Yes the secondary output side you can just loop the center tap and nail it to the screw your holding your transformer down to the chassie with, If your just useing a halfwave rectifier=2 Diodes feeding your regulator on your dc output you would have a standoff with no ground's, only 2 wire's for your DC voltage, a Plus and a minus, your DC feeder jack will only have 2 wires, atleast all the one's I've bought have just 2 wires, one for the tip and the other for the sleeve of the barrel or jack. Mouser sells these nice molded rightangle Jacks or mini jack's,
JD

[Peter Snowberg]

If you connect the ground and negative supply output together, you will short out the supply and let the blue smoke out. Please don't try that.

If you need a bipolar supply, there is no way to get rid of the 3rd contact and still be bipolar.

You could create a "synthetic ground" or "artificial ground" or "pseudo ground" circuit inside the effect and then switch to a single ended supply. In that case you would be adding a single ended to bipolar supply converter inside each effect. TI makes a chip for this use called a "rail splitter", but you can make a good one yourself with an NE5534 opamp and a couple of resistors. The rail splitter or synthetic ground circuit replaces the ground wire connection which is no longer required. The opamp outputs a voltage that is 1/2 of the way between the + and - power supply connections which is then connected to the effect ground.

Look at the diagram at the bottom of page 3 of this PDF file: http://www.msu.edu/~nandwan1/480/jamie.pdf

If you do that, the bipolar supply will be good for powering your converted effects, but you can't use it to power any other single ended supply effects. You also can't connect either of the power supply wires to the case. You MUST use an insulated jack.

There is always a tradeoff.

I hope that helps.

Take care,
-Peter