They don't say what technique is used in that ebay converter +12V -> -5V. But if it is an oscillator it usually results in a high pitch noise in audio equipment using it. Converting -12V -> -5V is more safe in that regard.

^ any info on how to do the -12v conversion? with an LM perhaps?

Yes, L79M05T seems to do that.

Checked the PSU, it delivers 0.3A on the -12v line... doesn't seem like a good idea to take from that and create -5v IMHO
It would be better to use a +12v line I think...

Or from +5V, google 'voltage inverter', see if there is one without oscillator/timer. I made one with a NE555 timer before, it was unusable for audio because of the noise in the line, regardless of the capacitors used.

The PSU itself can make -5V and -12V from Alternating current.

If you intend to use it for a sound card: Voltage inverters can produce noise, the LM7905 much less if it gets its stabilization capacitors.

h-a-l-9000 wrote:

If you intend to use it for a sound card: Voltage inverters can produce noise, the LM7905 much less if it gets its stabilization capacitors.

that's the case, I want the -5v line for the LAPC-I ... I still haven't found a solution/schematic on how to create -5v from (preferably) +12v for example...

Seem to recall the MAX232 being used to create -5v in a circuit. Don't know what the current draw is on something like a LAPC-I though.

http://www.societyofrobots.com/electronics_ne … _voltages.shtml

^ I see that each MAX232 delivers up to 10mA of negative current... too weak 😁

The MAX232 is a charge pump which also means noise.