1
\$\begingroup\$

I am in the final stages of building a fully analog synthesizer. Instead of using +10V, GND and -10V, could I switch these voltages to +20V, +10V, and GND to save weight, bulk, and size of a power supply that has to generate -10V? Would a voltage change generally affect audio circuitry or affect output voltage and ruin other audio equipment?

schematic

simulate this circuit – Schematic created using CircuitLab

Basically, is it the relationship between voltages or amount of voltage in this case? And what's the best way to create +10V on the board, since the solution in the schematic most likely isn't very efficient?

\$\endgroup\$
  • \$\begingroup\$ save weight, bulk, and size of a power supply ... why do you believe that is the case? \$\endgroup\$ – jsotola Feb 15 at 22:55
  • \$\begingroup\$ What currents are required for each of the rails? \$\endgroup\$ – hacktastical Feb 16 at 19:34
  • \$\begingroup\$ The whole unit draws 40W at full working load, so I wouldn't think I'd need anything more than 500mA. \$\endgroup\$ – zvolk4 Feb 16 at 22:57
  • \$\begingroup\$ @jsotola I am eventually selling the synths contained in a small metal enclosure. I'm trying to not add more weight to the unit, if I'm gonna be adding any weight I'd prefer to have it in an external power supply. \$\endgroup\$ – zvolk4 Feb 16 at 23:00
1
\$\begingroup\$

It's not a good idea to replace the voltage levels that a system is expecting. Unless you're modding the synthesizer to accept your GND, 10V and 20V. Audio systems generally have a bipolar supply because it's necessary for the opamps inside to properly amplify an AC signal ( you can't amplify a negative voltage if your supply only has a positive rail).

Regarding your second question, yes a voltage divider is a terrible way to source a reduced voltage from. You'd need a buck converter to help you out there. Probably an adjustable one, never came across a fixed 10V buck converter. Be aware of he current rating on it as well.

|improve this answer|||||
\$\endgroup\$
  • \$\begingroup\$ In an earlier question I was told that GND, -10V and -20V could be substituted for +10V, GND and -10V. Would this still hold up then? Or do I need to design a power supply with all those outputs? \$\endgroup\$ – zvolk4 Feb 15 at 21:25
  • 1
    \$\begingroup\$ @zvolk4 That completely depends on the circuits and power supply. If you have for example audio amp with say RCA connectors and a metal case, and a earthed/grounded power supply, obviously the RCA connector ground and metal casing should be at 0V/earth/ground level. If you replace the supply with 20V PSU, it must not be grounded itself, so you can use 10V level for the new reference voltage. \$\endgroup\$ – Justme Feb 15 at 21:41
  • \$\begingroup\$ @SimeonR Also op-amps can perfectly work with AC audio signals, amplifying them, and have AC audio output, without a bipolar supply for op-amps. \$\endgroup\$ – Justme Feb 15 at 21:43
  • \$\begingroup\$ @Justme I know, but does that extend to system that was originally designed with a bipolar supply? \$\endgroup\$ – Simeon R Feb 15 at 22:19
  • 1
    \$\begingroup\$ @SimeonR Indeed it does not extend -- A circuit designed originally for bipolar supply (such as DC coupled amplifier) can't be powered with single supply. However we don't know what zvolk4 is powering, except for a small snippet from previous question - which is a AC coupled amplifier with ground referenced output, with 0V GND, and two negative supplies, -10V and -20V. \$\endgroup\$ – Justme Feb 15 at 22:30
-1
\$\begingroup\$

If you don't need much current, it's not too difficult to make the -10 rail from the +10 one using a circuit called an inverting buck DCDC. That would be easier than trying to convert your bipolar design to single-ended, though that could be done as well.

EDIT: ok, 40W, so a good-sized supply. I suggest a pair of 12V switchers, with floating outputs, re-adjusted to 10V, wired head-to-tail to make a split +/-10V supply. Assuming equal loads, the supplies can each be 20W.

12V/20W is a popular LED supply, so you have an off-the-shelf solution, at least for prototyping. This type can also be had as an open-frame switcher, assuming you're willing to do the proper UL work to include it in your enclosure.

If space and cost was paramount and your volume justified it, a custom +/- 10V supply could be designed for your project. Cost in thousands could be less than $10. With some searching, there may be a suitable one already built.

|improve this answer|||||
\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.