Quote:
Originally Posted by Windston
I would have thought that I high res stepper motor would have been more accurate?
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Quote:
Originally Posted by Windston
I would have thought that I high res stepper motor would have been more accurate?
|
Windston,
It would be more accurate and the same thing occurred to me when I read Tim's post. For people who know a bit about electronics, geared stepper motors are definitely the way to go.
However, steppers are quite complicated to understand and hook up for people who are not knowledgeable about electronics.
Also, if you look at the barndoor, it is a straight tangent drive. So a high precision stepper is probably wasted. Other barndoors discussed here, have used curved drive threads to eliminate or at least minimize tangent error. The DC motor will be accurate enough provided the voltage is regulated. Seems like this will do what Tim wants.
Tim, if you want to go more precise later, there are people here who are happy to advise. Meantime, I suggest you run the motor from a regulated power supply like this one -
http://tinyurl.com/gudy5o2
and then control the speed with one of these pwm speed controllers
http://tinyurl.com/zjt65jr
If you have a 12V supply, make the first device generate 10V, then as the batteries start to go flat and lose volts, the motor wont change speed because the buck converter will keep pumping out 10V.
Use the second board to control the motor speed and adjust the pot to the correct tracking speed. Probably will cost less than $10 for both.
Both devices are very simple to hook up -
Buck converter is Battery in - regulated voltage out
PWM controller - attach the switch and pot as shown.
There are 4 connectors left. Bring in the regulated voltage from the buck converter to the input and attach the motor to the output.
If you need any more help or advice, feel free to ask.
cheers
Joe