Electronics > Electronics

current supply for servos

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jwatte:
I agree with jkerns. Amps are never "pushed" into a circuit, they are only "pulled" by the circuit. If the circuit tries to pull more amps than are available in the voltage source, the voltage will typically sag (drop) and you'll get brown-outs from electronics, and weaker performance from motors. You'll also end up stressing your batteries a lot, leading to shorter lifetime.

You should measure one of your servos in idle, and under load. Then multiply that by 14, and you'll know how much the entire robot will draw under maximal load. It may be that the 2300 mAh battery is delivering a lot less before it runs out, because the servos draw more than it's capable of delivering. That would change the equation for how much current you need in total. Thus, get a digital multimeter, and measure one of the servos first.

Or, if you get a bench power supply, it typically has an amp meter built in. You can get a 18 volts, 5 amps, supply pretty cheaply (as well as bigger things, like 30 volts 10 amps.) This will let you measure the servo, and deliver some amount of power -- it may be that 10 amps is enough for "normal" load on your robot, and you don't need the more expensive 30 amp supply.

Also, bench supplies have adjustments for voltage, and current. Typically, they will attempt to reach the given voltage, but if more current than the set limit is reached, they will supply a lower voltage. You can typically short-circuit these supplies without damanging them; they'll just limit the voltage to something very low, to keep the current under the set limit. For any hobbyist serious about electronic circuits, the three must-have tools are:
- digital multimeter
- soldering iron
- bench power supply

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