OK as you can see I'm new to the forums but I have had an arduino for about 3 months now, but messing about with some with the intent on sticking them in a robot. The servos are turnigy tg9e micro servos (Cheap and nasty i know dont judge ;)) and from what i can tell they require about 10ma when idle, 100-200ma when moving under no load and around 600ma when under load.
So I was wondering what sort off power supply I could/should use for testing since I don't want use batteries whilst I'm only testing
Well you have to consider the worst case which is all 6 servos will be drawing 600mA. That works out at 3.6 Amps.
Ideally you want a 6V source to power them but you can get away with a 5V @ 3.6 A external power supply.
So look for a 5V 4A power supply, a quick google search shows lots at quite reasonable prices.
I thought this might be the case, however would it be possible to use a voltage regulator (like the 7805) to get the voltage at a 5v at 1amp and then use transistors to get the required current to drive the servos?
Yeah sorry mike, I think I was barking up the wrong tree on that one, I was hoping to use a wall charger and a voltage regulator to get the required voltage, but I can find very few voltage regulators capable of dealing with 3.6-4A. So what I meant in my last post was using some transistors in either the common emitter or common collector amplifier configuration (not sure which would be best) to amplify the current to get the required current of around 3.6A. However an ATX power supply should suffice so never mind.
Thanks magnethead I didn't think of that, will have a look into that as well I got at least 1 ATX power supply lying about.
The power supply you are going to use with the 9g servos (I have a couple) depends on what you are going to do with them. If they will be lightly loaded you probably don't need a super large power supply. If they are loaded to max torque,the gears will probably strip. The below regulator chip is rated for 2a. For better performance, you can put a diode on the ground of the regulator chip to increase the output to ~5.7v. 5v is just barely above the usual minimum 4.8v servo spec. See if you can find a free/junk 9v-12v ~1a wallwart and see if it with regulator chips does what you need.
Thanks zoomkat just the sort of thing I was looking for. I don't think will ever need to go near to the maximum torque so I will give your suggestion a try.
to amplify the current to get the required current of around 3.6A.
When ever you amplify something you do not create it, you control it. So you can amplify a current up to 3.5A for sure but you have to have a source of controlling current to amplify like a small signal from a micro controller, then you have to have a power supply to provide that current. An amplifier only amplifies a signal it does not create anything that was not there in the first place. This applies to voltage amplifiers.
I used to joke with my students that as this op amp I was using had a gain of 10,000 then what would be the output if I put 1 volt in to it.
The answer of course is just the supply voltage (if it were a good op amp, less if not).