Mini Dual Power Supply

Even if the analog domain is not in my main area of activity, in many cases we are dealing with small signals which can not be used directly by an usual ADC (that we can find in almost any microcontroller these days).

For instance:

  • measuring the voltage drop across a shunt resistor
  • temperature measurement with thermocouple
  • use of a pH sensor in a microcontroller project
  • … many other cases
    all require the use of operational amplifiers.

Even if modern operational amplifiers are designed to operate with a single supply, sometimes the best results were obtained with a dual power supply; or sometimes it is cheaper/easier/faster to include a dual source in our project than to adjust/adapt to work with single supply.

So, this project has the following uses:

  • to replace main lab power supply in some experiments (experiments that are done in R&D phase for some specific projects). Sometimes this lab power supply is simply too large, sometimes I do not want to waste time to adjust each time the voltage at a fixed values (as 5v 9V or 12V);
  • as a blueprint/prototype for a small batch of PCB for personal use, because I need a few made for usual 5V, 9V, 12V and 15V;
  • as a verified project, ready to be included in “real projects”, with gEDA PCB footprints and schematics.

Schematic is simple, so simple that you can to order all parts by memory.


1000µF and 500µF capacitors may have lower values (like 220µF and 50µF … depends on your specific project).
This power supply is not designed to power large projects, but rather analog modules based on operational amplifiers (together with the microcontroller, obviously)


As we can see here I used 2200µF for C1 / C2 and 1000µF for C3 / C4.

Even if the module was assembled and tested I have some work to do, so I will update as I advance:

  • I have to finish gEDA project… to be sure of the validity of symbols and footprints.
  • I need to find (or make) a solution for housing; not only for this module but also for other “copies” that I will make with other values.
Updated: August 26, 2016 — 1:45 pm

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