Regulating Voltage

Technic-R-C

Hello,

I am looking to hook up a custom·h-bridge to my propeller to control a motor but I am having problems regulating my power supply for the 12V motor (pulls about 3amp).

At the moment I have a 16.5 volt Lipo battery·and a 7812 12 VDC voltage regulator, however the current limit for this regulator·is a bit too small at 1 amp.· I was wondering if three of these voltage regulators in parallel would give me a 3 amp limit (following resistor rules) which would be sufficient for my motor?· If this would not work could you guys please list out some other ways to regulate a 16.5 volt power supply to 12 volts at 3 amps. a transformer maybe?

Thank you

Technic-R-C

Phil Pilgrim (PhiPi)

Typically, you don't need to regulate voltage for a DC motor; and it's okay to use a supply higher than what the motor is rated for, as long as you regulate the current to keep it within the motor's specs. Does your H-bridge include a means for monitoring motor current? Typically, this will entail a low-value sense resistor in the source (or emitter) leg of the H-bridge. Also, by chopping the motor drive, based on the current feedback, you can vary the motor's speed.

-Phil

Bobb Fwed

I use this regulator: LM2596S-ADJ. It can output 3A at any voltage you want. I think it comes in a fixed 12V version as well. It's a switching buck regulator, so you'll need an inductor and a capacitor to augment the part. But it's been very reliable for me and buck regulators will give you better efficiency.

But Phil is right, a little higher voltage won't hurt.

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Technic-R-C

Thank you folks!

I finally found a circuit that would boost my current limit to 3 amps by putting three voltage regulators in parallel.· Although I do·like the other alternatives.

Regards

Technic-R-C

Ale

There is a simpler circuit to boost current using a PNP transistor 2N4398 if I'm not mistaken (it's been more than 20 years...) (PNP, 40 VCE, 25 or 30 Amps collector current, nice TO-3 metallic case). one or two resistors and that's all [noparse]:)[/noparse]. It is in the datasheet of the regulator, in a proper one [noparse]:)[/noparse]

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