Bipolar power supply out of a regular power supply?

[ethereon]

Hi,

I have the following problem : I have a triple output DC power supply (Agilent E3631) : +6V, +25V and -25V. I need to construct something that will enable me to have -12V to +12V across two terminals. The current requirement is about 7 A (driving a heavy motor).

What would be the best way to go achieve this? Any suggestions are greatly appreciated.

Thanks!

 

[IanP]

One option is to create so called "virtual ground" ..
If your power supply can deliver 25V @ 7A then:
you will need two power transitors (1xNPN and 1xPNP, Darlingtons) mounted on a heatsink, and here is explenation on how it can be done:
https://tangentsoft.net/elec/vgrounds.html
for higher currents reduce the emitter resistors (R3 and R4) to 0.1Ω or less ..

Rgds,
IanP

 

[Mr.Cool]

is this a DC motor? i have had similar problem before and i just put 24V across DC motor terminal - though it was only a 12V motor. it spins twice as fast.

yes motor is not rated for this so excersize care

Mr.Cool

 

[ethereon]

IanP : Thanks. That might just be what I need. I'll check it out.

Mr. Cool: Yes, it's a DC motor. The issue is that I need to alternate the direction of rotation at a certain frequency. Since I can program the power supply, I thought the easiest way is if I could figure out a bipolar power mechanism.
Optionally, if there was something akin to a "high-voltage multiplexer", where I could select which terminal output to select (-ve or +ve).

 

[IanP]

For changing direction you can employ the H-Bridge configuration ..
Here is an example:
**broken link removed**
In this circuit, the supply voltage can be 24V (and more, with Z1 removed) ..

Rgds,
IanP