Gallery, Projects and General > How to's
How to Make a Power Supply
Darren:
Sorry Chris, yes I know what vref is, but to what is it referincing?
I guess it's to the voltage regulator chip to set the output voltage to the motor. Which is very different to vref value.
That is, do not confuse vref with the motor requirement voltage.
raynerd:
Oh I see!! So the driver has a voltage regulator on it anyway so even though your running into it a 24V PS the regulator chip will reduce it to the required voltage to run your motor at 2.5A??
A couple of thoughts - why would it "need" to take in a 24V to throw out only 3-4V for the actual motor? Also, any 24V PS will be ok - but what current should it be rated - anything over 2.5A or should it ideally be a little higher?
All the best, I am understanding this a little more now.
Chris
John Hill:
I do not believe this is a simple thing that can be understood by refering to Ohm's Law.
The motors are not being fed simple DC, they are being pulsed at some high audio frequence (the description refers to being able to hear the motor making a noise in the windings).
Motors winding are highly inductive and it is a common practice to feed an inductive load via a resistance where a quick reaction is required. Ancient telegraph practice in fact. The principal is that there is a high voltage across the coil when there is a low current but when the current begins to flow so the voltage drop across the resistor rises and stops the coil overheating. I am not suprised that they are proposing such relatively high voltages for nominally low voltage windings.
Any power supply Chris that can provide at least the amps at the voltage you require.
raynerd:
Cheers for the info John - I`m going to give this spare laptop charger a go as it is rated 18-20v @3.79A. Please do tell me if this is well too low powered.
Chris
John Hill:
Chris, I think that is a little light on capacity but it might work.
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