Hi,

I have 2 power supplies but I need to obtain 3 voltage levels (+5V, +12V, -12V) to bench test a circuit board… is there a simple solution or do I have to use 3 power supplies?!

Many thanks,

John.

 

ideally you would need a -12V 0V +12 Volt psu, so you could the drop the +12 to +5 with a 7805 regulator.

What psu voltages do you have?

 

Here is how to connect to batteries to get +/- 9 volt. Just connect your power supplies the same way. To get the +5 volt. Use some voltage regulator like the LM7805 or LM317

 

Some computer power supplies provide +12v at high amperage , -12volts at low amperage and 5 volts at high amperage so If you got one of those that does it and if your circuit board doesn't need to much amperage at the -12v then you can u se it straight up I think

 

Hi guys, thanks for that!

The Power supplies are 3A/60V and 10A/30V.

Looks like a voltage reg is the way forward, so I just need to +12V and -12V from the 2 PSU's... thanks.

Think the power rails will need about 3A each, so I'll check out the 7805 and LM317 specs.

Thanks again guys

 

Hi guys, thanks for that!

The Power supplies are 3A/60V and 10A/30V.

Looks like a voltage reg is the way forward, so I just need to +12V and -12V from the 2 PSU's... thanks.

Think the power rails will need about 3A each, so I'll check out the 7805 and LM317 specs.

Thanks again guys

So if theses are ground isolated types, you could join them together + to - and make a centre zero psu , then you just need an LM337(neg) and and two LM317(pos) to give you the voltages you need , just omit the bridge rectifier.

PSU

 

Thanks Dave, I'll try that

 

Unless you can adjust the output voltage from your current power supplies, you will not be able to do as suggested. First the LM317 will fry at 60 volt. And then you will also have huge problem with power dissipation. That will also kill the voltage regulators. I suggest you go for using a old PC power supply instead.

 

Hi guys, thanks for that!

The Power supplies are 3A/60V and 10A/30V.

Looks like a voltage reg is the way forward, so I just need to +12V and -12V from the 2 PSU's... thanks.

Think the power rails will need about 3A each, so I'll check out the 7805 and LM317 specs.

Thanks again guys

The LM regulators give up to 1-1,5 amps max I think . If you are going to want more current then you will need to use a shunt power transistor with the Lm regulators.
I can provide a link to schematic if interested

Also , as mentioned above , 60 volts will fry the regulators . They are rated for 32 volts max I think

 

Are you sure you need 3A to test a circuit board??