wallwart power supply with tricky requirements

[gyraf]

On a side note, that way of acheiving +/- supply from a single transformer secondary is inherently problematic with certain types of 78XX-regulators. They tend to lock up if you start with a negative half-cycle when powering up.

See this:

http://wwwd.national.com/national/PowerMB.nsf/0/fb19f9d1b2e1d9b888256de2003db534?OpenDocument

Jakob E.

 

[Guest]

I can't see it. The link is dead.

 

[Guest]

Here is a page with good voltage multipliers. http://members.aol.com/sbench101/PowerSupplies/multiply.gif

 

[Guest]

Top will work fine. I suck with transistors but do you need a resistor in the base connection like a 22k?

 

[Guest]

I followed the phantom power portion of the G9 schematic at Jakob's site. It had a 2k2 on top and a 10k pot in series with a 22k resistor on bottom that parallel the zener and cap. That's why I thought maybe a resistor.

 

[gyraf]

If it's this:

http://img.photobucket.com/albums/v251/buttachunk/supply1phcopy.jpg

Then I don't think your doubler C1-C2-D1-D2 will work - the negative side goes nowhere as far as I can tell..

Jakob E.

 

[peter purpose]

Would this do you?

 

[peter purpose]

Ha ha :green:
I can't take credit for it though. I just took Justin's standard supply and lopped off the positive rail.
I have no idea if it works..!! Have to wait for the smarties to give it the once over.

Toodle pip

 

[gyraf]

looks good.

You may not need the 22R/5W and the second 3300uF

the 150R does not have to be 2W if it's only for phantom power

 

[peter purpose]

Top Smartie has spoken...you have clearance for take off.

 

[Guest]

Maybe not necessary but the standard diode protection after the 7924 could be added.

 

[JLM Audio]

You can just leave the + rail off the PDF circuit below and half the pump charge circuit to run it on one AC winding. It works perfectly.

http://www.jlmaudio.com/JLM ACDC Schematic.pdf

You can make a small PCB or use our PCB which is only 3.2" x 1.6" and just need to leave off the parts with a cross.

Hope this is of some help

Joe