Is plywood box safe for mains powered PSU?

[electr_peter]

Local electronic shops had selection of torroids marked for halogen lamp use(?) and various non-torroid types. I chose split bobbin type 2*12V ~1.5A for main transformer. Two secondaries will be connected in series to boost available current. Other circuit components will be powered by low power 9-0-9V transformer.

Wood is fine for low power projects, but it's a really bad idea to build a PSU inside a thermally insulating box.  It will make cooling very difficult.  Use a metal box.

Will wooden box with vent holes be good enough at maximum total power of PSU at 40-50W?

Link to thread with initial PSU schematic: DC PS with strict current limiting on short circuit

[edavid]

Will wooden box with vent holes be good enough at maximum total power of PSU at 40-50W?

No, you would need a fan.

[Zero999]

Think about the Watts of heat produced and the physical size of the unit rather than the output power of the PSU. If you have an enormous heat sink, then a wooden box with adequate ventilation will be fine without any fans.

Wood does look nice but one of the good things about metal is you can use it has a heat sink. I've designed a small LM317 bench power supply with the metal enclosure used as a heat sink and it worked perfectly.

[Red Squirrel]

If your PSU is efficient enough, it should not be outputting that much heat anyway.     We have about 1600 amps @ 54vdc being pulled from our rectifiers at work and I can stand behind that rack without sweating...much. Mind you the room is AC cooled... it would get hot in there without the AC, but probably not anywhere as bad as any other equipment room.

That said *DO* put fans and a thermal sensor so it can shut down and/or output an alarm if it overheats.  If you want to play it very safe you throw in a smoke detector that also shuts down and outputs an alarm if there's smoke.

[electr_peter]

I calculate worst case dissipation for any single device as 12W(3A*4V voltage drop). Quite manageable with heatsinks and holes in the case.

I decided to use plywood box and cover all inside surfaces with copper or aluminium foil. Thermal conductivity is great, it forms a good shield as well. Electrical conductivity of foil glue is in question, but there are ways around it.