Can get negative voltage from HD Plex 300

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fdojose

Member
Joined 2020
#1
Hi guys, I need your advise, for a project I need +5v gnd -5v, I have a HD Plex 300w power supply and I´d like to use it, but it only give + voltages.

Do you know if there is a way to get a negative voltage from any where inside that psu?

I know I could do it with an oscilator, diodes and capacitors, but could be more elegant just to get it from psu.

Thanks,
 
#2
Can you give more details and a schematic for your project? Also, how much current is required?
How important is noise? It is not likely that you could use internal connections for a negative supply.
 
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#4
Yes, it's possible that the supplies are all isolated from each other.

Turn off the power and measure the resistance between the two grounds of the adjustable outputs.
If and only if there is no connection, you can connect the two variable supplies in series and ground
the common center connection. This would create a dual +/- supply as you want.
 
#5
rayma said:
Can you give more details and a schematic for your project? Also, how much current is required?
How important is noise? It is not likely that you could use internal connections for a negative supply.
Click to expand...

My project is an Streamer with:

- Raspberry Pi 4B (Moode 6.7)
- Soekris dam1941
- I'll test Ian Canada FiFo Ultimate
- I'd like to use an external PSU, if is possible this that I had, HD Plex 300

The dam1941, needs 2 sources a +5V for digital and +5v-5v for analogue.

Thank you,
 
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#6
rayma said:
Yes, it's possible that the supplies are all isolated from each other.

Turn off the power and measure the resistance between the two grounds of the adjustable outputs.
If and only if there is no connection, you can connect the two variable supplies in series and ground
the common center connection. This would create a dual +/- supply as you want.
Click to expand...

Tested, no connection between grounds.

So, Do I just to invert cables?
Can I use both for analogue and one for digital?

Thanks,

P.S: One measure 5.19v and the other 5.22v.
 
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#7
You can do as you want with all of the floating outputs, except do not connect them in parallel.

Connect the two variable outputs (each set to 5V) in series, positive of one to the negative of the other.
Then the center connection is ground, and the other two outputs are the +5V and -5V.
Be sure to connect the supply ground to your circuit ground.
 
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