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I currently use PicBasic Pro. Thanks
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Electronics speed control
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I currently use PicBasic Pro. Thanks -- ___________________________________________________________ |
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I use speed control for fan motors all the
time.
You have two choices:
1: Analog - convert PIC PWM to dc voltage
with RC network. Use op-amps and P-channel FET to convert
0-5V level to 0-12V level
(or whatever your motor requires). Simple, easy to understand, but wastes
a lot
of power as heat.
Useful only for small motors.
2: Pure digital - Use PWM output directly
to drive FET driver (and power P-channel FET). Filter the output with
an L-C network.
Can handle larger motors. Very efficient.
I have used both methods, and control the
"high side" rather than than the "low side" so that the motor
tachometer
can be ground-referenced.
You have to pick which one works best for you,
but I can give examples of either.
Charles Linquist
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Thanks for the reply Charles. This E.speed control will be connected to a radio control receiver. So, I am assuming that I will have to go through the digitally. As the receiver gets the signal to vary the speed, the motor should correspond directly. Either speed up or slow down. I understand I can just buy it for a 20 buck of the hobby stores, but I guess I just want to go though the hassle of how it actually works. What actually happens when the the PIC receives a signal through the RX? I use speed control for fan motors all the
time.
You have two choices:
1: Analog - convert PIC PWM to dc voltage
with RC network. Use op-amps and P-channel FET to convert
0-5V level to 0-12V level
(or whatever your motor requires). Simple, easy to understand, but wastes
a lot
of power as heat.
Useful only for small motors.
2: Pure digital - Use PWM output directly
to drive FET driver (and power P-channel FET). Filter the output with
an L-C network.
Can handle larger motors. Very efficient.
I have used both methods, and control the
"high side" rather than than the "low side" so that the motor
tachometer
can be ground-referenced.
You have to pick which one works best for you,
but I can give examples of either.
Charles Linquist
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Could you give a PicBasicPro example
of the pure digital? Also the filter output L-C network?
Ever had success using either reverse
emf or magnetic-inductive to determine the speed of the motor?
Thanks
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----- Original Message ----- From: randy ram To: Sent: Thursday, May 06, 2004 4:04 PM Subject: [piclist] Electronics speed control Has anyone worked on a speed control before. I want to drive a small dc motor. The same as the radio control electric motors. I currently use PicBasic Pro. I've used PWM successfully for this sort of thing - it was quite easy. I used an AVR rather than a PIC, though. I was driving an optical chopper disk, and got the speed feedback from that and used it to stabilise the speed (I needed 50 Hz). Leon -- Leon Heller, G1HSM http://webspace.webring.com/people/jl/leon_heller/ |
