The title pretty much says it all. I'm on a team that is currently building a robotic arm for the capstone project of my engineering degree, our design is similar to the Dobot (5 degrees of freedom). We purchased our 6 servomotors, and each one requires 2A at 6V.

From my preliminary research, I haven't been able to find a power source that could satisfy this. We'd rather not purchase six individual AC/DC power source for each servo, and we've heard that these can introduce problems, as they aren't necessarily voltage-regulated. Another suggestion we've received is to buy a computer power source, and modify it to output our the voltage and amperage we need. This raises some concerns, since our professor running the course might find this dangerous.

We'd like some input into how we can power our servos effectively, without going overboard on costs (we are students, after all).



Search aliexpress for '6V switching power supply'. You should find 5Amp or 10Amp ones for $10-$20. Silver boxes with holes in them. You can find them on ebay as well (usually the same chinese vendors as aliexpress).

You will need to add your own AC plug.

Keep in mind that you will probably not be using 12Amps because not all motors will be at full torque at the same time.


Working with a low voltage power supply, which is not modified/hacked is way less dangerous then a robot arm with 120Watt. This guy will hurt you more. Anyway your idea with the power supply of a computer is a pretty economic one. Sure there are 6Volt AC/DC Converters on the market. They just cost a bit in a 120Watt version. But the question which remains is how to get the 6Volt out of the 12Volt power supply?
My suggestion: Use basic LM350 chips. Those little guys provide you with an adjustable voltage and up to 3amps. Place one curcuitry before each motor and you are fine. These chips are not voltage controlled. You adjusted them with a resistor at one pin. There are other chips which are voltage controlled (also for 6volt) but I can't remeber their names right now. With this setup you have to buy parts for around 10USD (I assumed you will find an old computer power supply).

  • $\begingroup$ Thanks for the feedback! I like the idea, but I'd be a little worried about cooling those LM350's. The spec sheet says that we'd probably have a 22 degrees Celsius temperature differential at 12 W (Thermal Resistance, Junction−to−Case). Have you worked with these chips before, and do you think this would be an issue? One alternative might be a simple switch, although I've never worked with these either. What are your thoughts? Thanks again for your help. $\endgroup$ – Emzam Nov 17 '15 at 20:55

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