I've got a power supply that'll deliver 0.5-1A (depending on a later design decision), and a motor that will normally draw about 150mA, but its stall current is a whopping 2.1A. In my application I shouldn't stall very often or for more than very brief periods of time, but I may stall nonetheless, and it's very important that I don't draw too much current from my power source.
I can only assume this is a common problem with a simple solution that I'm unaware of because I'm a total newb. My instinct is to provide a secondary source of power that can supply 2.1A momentarily, like a battery or a big juicy capacitor, and something to sense current from the normal power supply and cut it off or limit it if it gets too high. I'm really rather radically unprepared for coming up with a way to do this on my own, however.
Any suggestions?
Best Answer
Some power supplies are designed to safely 'fold back' the voltage when the current demand goes too high. This means that once you reach the max current, if the load resistance decreases so as to demand more current, the supply voltage just decreases so as to keep the current from exceeding the maximum.
If you have that kind of supply, you should be fine. If you don't have that kind of supply, then it's simply under-rated and you need one that either (a) has the fold-back feature, or (b) can supply the 2.1A, with a comfortable safety margin.