So this question is for the hardware/psu gurus. I'm powering a Neptune heater in my house with server PSUs that don't have native 5v output. I'm using
this to step 12v down to 5v to power the KNC controller.
I ordered it a little quickly, and didn't notice that in its specifications ripple is listed as 200mv which is insanely high compared to ATX specifications of 50mv max on the 5v rail.
My question is, how dangerous for the controller is this? Am I looking at imminent death? How would I go about smoothing out the ripple to acceptable levels? I do have server PSUs with native 5v output, but they're less convenient for in house use. I guess I should possibly just use one of them with a single cube to take advantage of it's clean 5v output.
You could use an electrolytic capacitor across the 5V +/- output. These capacitors are polarized, so the capacitor + Plus goes with the + power supply output and negative - goes with the negative of the capacitor.
https://www.radioshack.com/products/radioshack-4700uf-35v-20-axial-lead-electrolytic-capacitor?variant=5717323269This sells for about $5. It's rated at 35V so you are safely over the 5V working voltage.
If the ripple is still to high, just add another capacitor in parallel. If they are out of stock of this value, just buy the highest value 35V electrolytic capacitor.
For super duper anal retentiveness, add a 5 or 10 microfarad tantalum electrolytic in parallel to damp down higher frequency transients.
Naturally do all this stuff with the power off! Tape or cover up all exposed wires.
Future enhancements if you have power glitches:
This would take some more electronics knowledge, but you could think about using a super capacitor that can safely handle 5V DC. The super capacitor would store enough energy to ride through any millisecond(s) length power brownouts.
