problems in driving a motor
Dan Michaels email (remove spam text)
Liew Tze Haw wrote:
>> From what you are writing it sounds like you are driving the motor
>>directly from the PIC. Unfortunately you cannot do that, motors require
>>of current (especially at startup and stalls) and put ALOT of noise on
>>line connected to it. It doesn't sound like you need the motor to reverse.
>>recommend using a transistor as your driver, if it is a small motor a
>>or 2N3904 would be fine. TTYL
>Do l need a separate power supply(battery) for the transistor? l tried the
>method above by using the same power supply(with the rest of the circuits)
>but it still cannot work well. l don't know what is the reason for this.
You have to break this problem apart, figure out what is happening
with the individual pieces, and only then put the pieces back
1. Determine what it takes to run the motor all by itself. Run it
off a variable power supply, or from C- or D-cells directly. First,
1 cell, then 2 cells, etc. Determine what seems to operate the
2. If the motor takes some voltage other than 5v and 25mA, which is
a leadpipe certainly, then you cannot run it directly off the PIC,
and have to build a driver ckt, as Dave said.
3. Build the driver ckt all by itself, get the motor running, and
only then think about connecting it to your PIC.
This is how an engineer attacks a problem like this.
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