Convert single to dual supply

[Wombat2]

I bought one of these on eBay

An externally hosted image should be here but it was not working when we last tested it.

but then discovered it was single rail supply not dual. the connection for GND is just that - chassis ground with no potential between the +/- and the GND terminal.

Is there anyway I can get some sort of dual supply even temporaly for low voltage testing before applying full power to a new project?

Otherwise it's a good little power supply

 

[ostie01]

One way of doing that is you can place 2 high wattage resistor in serie between + and ground. The + become the positive power supply, between the 2 resistors is the potential ground and the ground of the power supply become the negative .Both resistor must be of equal value since you do not want your groung having +/- a couple of volts.

This is one way that can be use easily and pretty fast, good luck

 

[gmphadte]

Use a power opamp and make a virtual ground.

Gajanan

 

[henry zhang]

Hello!What's "chassis ground ",please?Do you mean that this power supply is broken?Thanks

 

[richie00boy]

Use a power opamp and make a virtual ground.

Gajanan

Yes see the virtual earth for car audio project on the ESP site. Don't expect much out of it though, but then again the supply is probably pretty weak anyway so may well be complementary.

 

[richie00boy]

Hello!What's "chassis ground ",please?Do you mean that this power supply is broken?Thanks

Chassis ground means it's just a terminal connected to the case and presumably mains earth. Otherwise the supply is floating, this gives you the option to earth it.

 

[traderbam]

How much did it cost on Ebay? If cheap enough you could always buy another one and wire them in series, assuming they have
floating outputs.

 

[richie00boy]

I would imagine with the separate earth terminal they would be fully floating

 

[henry zhang]

richie00boy,thanks for your explanation.

Wombat2,
I happen to found such a powersupply yesterday.Refer to the following pictures.I opened it last night and I found that there was only a large transformer and several pieces of PCBs in it.So I advice you to mend it for yourself,if it is possible.Make sure that you will not be shocked by the input current.Good luck.

 

[richie00boy]

there is nothing to mend. He just needs a supply splitter or another supply the same.

 

[henry zhang]

Oh,maybe I misunderstanded his meaning.Thanks

 

[Wombat2]

A couple of 1K 5 watt resisters work

 

[Christer]

A couple of 1K 5 watt resisters work

Only approximately and only if you load draws much less current. And you don't get good regulation anymore, unless your load draws constant current. It works in some cases, but it is no general solution.

 

[richie00boy]

Indeed, you won't be able to connect a speaker return to there.

 

[sivan_and]

Budffered virtual ground

Budffered virtual ground...
OP amp=OPA549

 

[Wombat2]

Only approximately and only if you load draws much less current. And you don't get good regulation anymore, unless your load draws constant current. It works in some cases, but it is no general solution.

Only want to check new circuits at low voltages to make sure there are no holes to let the smoke out then I'll hook it up to the full PSU to run at full power

 

[gmphadte]

I have a feeling that audio power amp IC can be used as a power amp for making virtual ground. Select a 5 pin IC like TDA2030 or something alike depending on ground current required.
Not a good solution than a second PSU, but in case...

Gajanan Phadte

 

[Christer]

Only want to check new circuits at low voltages to make sure there are no holes to let the smoke out then I'll hook it up to the full PSU to run at full power

Still, your load must draw much less current than those resistors, or draw approximately equal current on both rails. It can work, but only under certain conditions.

 

[richie00boy]

I have a feeling that audio power amp IC can be used as a power amp for making virtual ground. Select a 5 pin IC like TDA2030 or something alike depending on ground current required.
Not a good solution than a second PSU, but in case...

Gajanan Phadte

That's exactly what sivan_and posted just above you

 

[N-Channel]

DC-DC converter

Wombat-

Whar voltage(s) do you need? How much power? One possible solution is a DC-DC Switched-mode power supply. There are many good schematics out there that are easily scaleable for just about whatever voltage, current and power levels you could want.

Check out Rod Elliot's ESP website, as richie00boy suggests, but look at the car amplifier power supply projects. These can be adapted to whatever your requirements are.

Steve