+/- 17V (or 25 or 34, etc.) from one 9V battery, Success!

[w!ll]

I breadboarded this up using an LT1054 after messing around with the GGG bipolar supply, as i thought it might make an easier alternative (it's easier to find a regulated 9vdc PS than an 18vAC one), and isolated from any circuit it works perfectly, hooking it up as the power supply for a ring modulator (AD633 and ICL8038) i'm working on however, and the voltage drops to almost zero. Max output current for the LT1054 is 100mA, would a greater current draw from the ring modulator cause the voltage drop? It's a clone of a commercially produced ring mod (don't know if i can say who?) and they state it needs a 100mA PS.

[cpm]

You can look how much current is demanding your circuit with a multimeter.
Anyway, if you produce a 36v output (+-17v?), the LT chip would need ~x5 the current from the 9v source. As the datasheet says it stands 300mA, that may give you some 50mA (look for actual numbers there).
Your 8030 claims 20mA, add some opamps and other candies to that, and you'll hit the ceiling easily.

However, usually you can redesign some parts of the circuit (if not all) to work from 9v. That will save the bipolar power only to those section where its actually needed. For example, put out the LEDs, logics, buffer... and any other audio section that can be AC coupled and doesnt need that extra headroom.

I (we) would very like to see that schematic 

[isildur100]

Yes I think the problem with voltage pumps is the amount of current. I recently tried the bipolar circuit with MFOS sub commander and it looks like it can't supply enough current.

I wonder if I would have more success with the 555 setup instead of a max1044

[Slade]

Here's a little layout I made for this thing. Not verified yet, please check before use!:



Regards,
Fernando.-

EDIT: BTW, thanks, Brian!

[Slade]

Okay, so I tried this circuit feeding a moosapotamus Fat 'n' Pretty I'm working on (fantastic proyect). The layout I made for the MAX1044 circuit is now verified, it's working fine. I'm getting +/-17.2v from a +9.3v PS.

The problem is that when I connect the circuit to the +/-15v inputs of the F'n'P I'm getting +16.5v and -15.2v, and I think this is what is causing the "whine" and "interference" noises I'm getting from the circuit. The controls are ok, everything works but I'm getting this noise. I changed the voltage filter caps at the out of the MAX1044 circuit for two 47uF, but the noise is still there. I think I'll use some 7X15 regulators or 15v zener diodes at the output to keep it stable and "equal" to feed the F'n'P.

Any thoughts on this?

EDIT: Here's the F'n'P schematic

[.Mike]

Any thoughts on this?

Just a shot in the dark, but have you considered whether or not your circuit draws more current than the 1044 can source?

[PRR]

> what is causing the "whine"

Your voltages would be fine if they were clean.

The '1044 oscillates at a near-audible frequency. There is substantial "whine" ripple on its output. Your JFET stage has nearly no supply ripple rejection; the 5532's rejection declines at high frequency.

So yes, there's whine coming through.

Add some filtering. As much series R as you can stand; I figure 10mA-20mA for that F'n'P, which can clearly work with +/-15V (probably much less), so 100 Ohms will give a tolerable 1V-2V drop. Then add enough shunt C to low-pass far-far below the unwanted frequency. Since you seem to have 10uFd parts handy, I picked that: 100 ohms and 10uFd is 159Hz. This is 30 times lower than the lowest likely MAX1044 frequency, whine should be 30 times less, which is a big difference. We could compute more closely, but the cost of 100r+10uFd is so low it is cheaper to try than to figure.



Also: take power right AT the cap. Your layout's +17V terminal is "upstream" of its cap; the -17V cap layout is better. In this case, the 2mm of "excess" trace is not a problem worth fixing. Anyway the '1044's ripple exceeds any wire-induced ripple. But good general layout.

[Slade]

Thanks for your answers!
I'll let you know how it works.