"Acceptable" level of power-supply noise for a console?

[Kchula-Rrit]

Just wondering what the power-supply noise immunity for the console is...

I bought a MeanWell RT-65A power supply (from Jameco Electronics) for the BATcomputer until I can fix the battery power supply.  The data sheet says the noise should be 80mV peak-to-peak.  I measured it to be roughly +60mV, -50mV with my storage scope and tried combinations of capacitors and inductors to reduce the noise, with little effect.  Then I just turned the power supply off and checked the noise, which was +30mV, -24mV.

If the "unpowered" noise is a component of the total noise, then the noise contributed by the power supply would be +30mV, -26mV.

K-R.

[JJB]

For what it's worth, I have replaced the power supply board of both my 99/4a consoles with a combination of small switching buck and boost converters. I did spend considerable time trying to reduce the ripple. For +5V I ended up at ~40mV (from ~60mV) by adding some capacitance and inductance at the output, purely by experimenting. I didn't bother with the other rails (+12V and -5V) even though the ripple was a bit higher on both (I think). I haven't seen any negative side effects whatsoever but definitely one positive one: cool to the touch 🙂

 

FYI I am building a Geneve stand-alone system and have replaced all those local linear regulators with the same sort of power supply you're using. It works a treat (haven't measured ripple). 

[RickyDean]

I'm starting to change out regulators on my Foundation z80 card, HFDC's, and other to these type of units from Mouser, VXO7805-1000 https://www.mouser.com/ProductDetail/CUI-Inc/VXO7805-1000., Non-Isolated DC/DC Converters 8-36Vin 5Vout 1A 5W SIP. I'm waiting for the 12 volt version to come in too.

[Kchula-Rrit]

1 hour ago, JJB said:

For what it's worth, I have replaced the power supply board of both my 99/4a consoles with a combination of small switching buck and boost converters. I did spend considerable time trying to reduce the ripple. For +5V I ended up at ~40mV (from ~60mV) by adding some capacitance and inductance at the output, purely by experimenting. I didn't bother with the other rails (+12V and -5V) even though the ripple was a bit higher on both (I think). I haven't seen any negative side effects whatsoever but definitely one positive one: cool to the touch 🙂

 

FYI I am building a Geneve stand-alone system and have replaced all those local linear regulators with the same sort of power supply you're using. It works a treat (haven't measured ripple). 

 

Thanks for your info, and I am glad that your new supply works.  My console has a USB keyboard adapter and a reset switch where the "coffee boiler" went, so any power is external.

I should have mentioned that my tests were with no load on the supply.  I will have to see if adding the console as a load will help with the ripple. 

[Kchula-Rrit]

35 minutes ago, RickyDean said:

I'm starting to change out regulators on my Foundation z80 card, HFDC's, and other to these type of units from Mouser, VXO7805-1000 https://www.mouser.com/ProductDetail/CUI-Inc/VXO7805-1000., Non-Isolated DC/DC Converters 8-36Vin 5Vout 1A 5W SIP. I'm waiting for the 12 volt version to come in too.

I have been thinking of doing the same thing with my PE boards, also.  Shift838 gave me a Mouser part number for a 2-amp part that does the same thing.  He mentioned it here, in the conversation about the new IDE board.

K-R.