====== What ======
A simple adjustable DC power supply: hardware

For more info, read about [[start|openbench]]

====== Notes & stuff ======
===== Design constraints =====
Outputs:
   * 2 adjustable outputs
   * 1 fixed output

Voltage:
   * adjustable outputs: 0-30V, adjustable
   * fixed output: 5V

Current:
   * adjustable outputs: 0-2A, adjustable
   * fixed output: 2A

Indication:
   * voltage (for adjustable outputs only)
   * current (for adjustable outputs only)
   * current limiting active (constant voltage / constant current) (all outputs) (red LED)

Options:
   * combine to 0-60V / 2A (series)
   * combine to 0-30V / 4A (parallel)
   * link voltages (can be used for parallel mode or symmetric output)


====== comments ======

What happens when the power supply output voltage is set to 3.3 V, and I hook that output up to a 12 V battery?
Which is better:
   * The PSU pulls the voltage down to 3.3 V (or as close as possible until it hits the current limit)? or
   * The PSU supplies zero current, letting the voltage float up to 12 V?

----

Should have a 3.3v fixed output as well as the 5v.  Easy enough to handle.  1A should be good for most purposes on the fixed supplies.  Elektor ran a switching PSU module in April that I made some tweeks on and currently as waiting on boards. Galvanically isolating the adjustible supplies is a potential issue.  As soon as you hook a meter panel up, the two supplies are tied together. Hack around it by using two MCUs for A/D and transmitting to a third one via optoisolators?--pstemari

====== Further reading ======

   * "Bench power supply tutorial" https://www.adafruit.com/forums/viewtopic.php?f=8&t=24200
   * "Bench-Top Power Supply" by James Littlejohn for the Tulsa Electronics Club
   * "Building a digitally controlled bench power supply using an AVR" http://electronics.stackexchange.com/questions/18249/building-a-digitally-controlled-bench-power-supply-using-an-avr
   * DIY Variable bench power supply http://www.instructables.com/id/DIY-Variable-bench-power-supply/
   * DIY PSU into Bench Power supply http://www.instructables.com/id/DIY-PSU-into-Bench-Power-supply/
   * DIY digital bench power supply http://hackaday.com/2011/06/06/diy-digital-bench-power-supply/
   * My DIY Bench Power Supply http://www.swharden.com/blog/2012-12-18-my-diy-bench-power-supply/
   * DIY Bench Power Supply http://www.adwiens.com/projects/electronics/07/index.html