ZOE - Small PSU
This is a super small PSU for powering only a few ZOE modules. It is a linear power supply with no current limiting, thermal protection, and only the most basic of filtering and ripple suprression. What this is though is a starting point for me to build and improve upon as I design larger power supplies with a bigger feature set. It should get the job done at the start, and once I am better and designing power supplies I can come back to it and add more.
This power supply is intended to mount inside a small enclosure with an external off-board transformer and power input module. I intend to use a Corcom power input module with built-in filtering so that there is at least something. The transformer is intended to be a Hammond Mfg. Power Transformer with a 120V primary and two 14V secondaries to get the +/-14V needed for the 7812 and 7912 to generate the +12V and -12V lines for the PSU. The +5V supply is a 7805 that is powered by the +12V rail.
This supply design is a combination of my own design, the MFOS Adjustable PSU, and the recommended design guide from the 78XX/79XX linear voltage regulator data sheet.
Warning: Other than the fuse in the power input module, this supply has no other fuses or current protection circuitry. Therefor it is dangerous and should only be used in a lab environment with experienced operators. Using this supply runs the risk of damaging anything connected to it, and also damaging the supply itself. Be careful when using it.
Another Warning: I don't believe this board is compliant with the Canadian Electrical Code or the Ontario Electrical Safety Code, and thus would likely not meet the electrical safety requirements in any other jurisdiction. Another version of this board will need to be developed for general public use.
A Note on Capacitors
This boarrd features some big scary capacitors that don't have any means of discharge when power is disconnected. Please be careful when servicing the supply or using it outside of an enclosure (or with the enclosure open).
Recommended method to discharge: use a 100 ohm resistor to short the unregulated +14Vdc and -14Vdc rails to ground.
Revision List
Rev 1.0 - December 2024
- Created the design, layed out the board, generated the output files, did all the things for a very basic PSU design.
- Board features LEDs to show status of each power rail
- Board only has traces on the bottom, but is a two sided board to create a massive ground plane
- Should have ample smoothing, but once I build the first unit some testing will need to be done with my scope to actually see how good it is.
- PDF of the schematic
- List of Materials
TODO list/future features:
- Proper current limiting or fusing on each output rail
- Input filtering on the board itself
- Transient supression on the board itself
- A method of discharging those big scary dangerous capacitors when the supply is switched off