Mutron Phaser II power supply using TC962CPA

[armdnrdy]

Hi,

I'm building a Mutron Phaser II from the ground up. I have seen where a MAX1044 has been used with success to create a bipolar power supply resulting in 8-9 volts instead of 11-12 volts as in the original design. After much research about bipolar supplies, charge pumps, etc, I decided on the TC962CPA for needed voltage and current. I have a DC Brick which has 9 VDC and 18VDC outputs. Utilizing an 18VDC output, a LM7812, and a TC962CPA, I put together a supply that I hope will do the job of creating -12, 0, +12.

Can someone please be so kind as to take a look at the design and tell me what you think?

http://www.aronnelson.com/gallery/main.php/v/Schematics-etc/Mutron+Phaser+II+power.jpg.html

Thanks,
Larry

[armdnrdy]

No input from anyone? I just want to be sure that this is going to work before committing this design to a board.

I would appreciate any input.

Thanks,
Larry

[Seljer]

Depending on what your chip can handle, take the output for the inverter chip directly from +18V then regulate it down to -12V with the a LM7912 negative regulator

[cjlectronics]

If you are building it from ground up then use a linear bipolar power supply.  The charge pumps are nice but they come with an internal clock frequency that can sometimes get into to your signal.  A linear supply that can push 500mA should be plenty and I'm sure you can build it for less than $10, plus it's quite (as in no ripple with the right capacitor filtering), and you can use +/- 12 or 15 volts for plenty of headroom.  Real estate is probably the only negative thing about it.

CJ

[armdnrdy]

Hi cjlectronics,

Thanks for the reply. I designed the board to fit in a 125B enclosure, so there isn't enough room for a on board power supply, and the interior of my pedal board's A/C power is taken up by two space grabbing wall warts. That's why I am leaning towards a bipolar design incorporating a charge pump. The TC962's spec sheet states that if you ground pin 7, it will double the oscillator frequency to 24kHz, which should render any whine inaudible. I would like to hear from those who have has a noise issue and how they remedied it. (filtering caps etc.) I also would like someone to verify that the 18VDC ground/negative serves as the 0 volt / common ground between the positive and negative voltage.

Any help is appreciated,
Thanks,
Larry

[Processaurus]

Your 7812 wants some .1 caps to ground on both the input and output for stability, as per the data sheet.  Also in your board layout, it would be a worthwhile precaution against noise to star ground the charge pump back at the power supply.

Don't see any other issues, but breadboarding designs before making a fancy PCB can save a lot of heartache.  I've never gotten a perfect design first shot, and PCB's are a lot squirrelier to debug than a breadboard.