Hi everyone.

I'm wanting to use a 0 - 10 VDC analog output from a PLC to supply voltage to a model railroad track. The PLC analog DC output is limited to around 40 mA, however I would like to supply 2 or 3A to the track. I'd like the PLC output voltage to match the voltage that's being sent to the track, so since I don't need to perform any type of scaling on the voltage, it would seem that I just need some sort of simple current amplifier.

I'm sure I could design and build something from scratch using transistors, but for the sake of saving time and keeping things tidy, I'd like to get something off the shelf or a kit with a PCB, parts, and terminals that just requires soldering. Does anyone have any recommendations for a product that would be ideal for this application? I'm guessing that this kind of current amplifier is frequently needed for Arduino and Raspberry Pi projects, so hopefully there's something out there (perhaps some sort of Arduino or Sparkfun kit) that would be ideal for this application.

Thanks!

 

Well, if you decide to do it yourself...

It sounds like you could use a voltage follower Op Amp boosted with a transistor in emitter follower mode.

Just as simple as any kit.

 

Or a voltage regulator IC. Will require an external DC power supply to deliver the 3 amps needed.
Steve G

 

Don't know that you will find a kit or anything already built.

Below is the LTspice simulation of a simple circuit using an LT3083, 3A, low-dropout regulator whose output voltage equals the SET input voltage (without the usual 1.2V offset of an LM317 or LM338 type regulator).
The maximum output voltage is about 1.2V below Vcntrl (Vcntrl is a low current bias input that can be set to a higher voltage than the IN voltage to minimize the dropout voltage).

Note that the power dissipation in the regulator can exceed 10W, so it needs to be on a proper heatsink.