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Controlling PCM servo with switch

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Old 02-18-2007, 02:17 PM
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makterna
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Default Controlling PCM servo with switch

Electronics question, regarding rc-servos:

I am aware of how PCM coding works, but if I have an application where I only need the two extreme positions of the servo. Can I just send 0V for one position and 12V for one position? Some manufacturers say no, that I need a frequency too, but I remember having tried this in practise, and found it to work.

If not, can anyone please show me of how to make a simple resistor-capacitor circuit to create the frequency needed to make the rc-servo work?

I also want to know if I can connect two 6V servos in line with eachother, to a 12V power source. The servos are going to be operated simultaneously.

I would also appreciate recommendations of servo manufacturers. I need a servo which is weather resistant but otherwise reasonably priced. It's for a commercial invention that I'm trying to develop.

If it matters, I'm located in Sweden.

Best regards,
Erik
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Old 02-18-2007, 03:07 PM
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DKjens
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Default RE: Controlling PCM servo with switch

Erik,
If you haven't already been there, you may want to try to post your questions on www.rc-unionen.dk I can think of a few people on that site who I think can give you your answers, and it's local to you as well.
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Old 02-18-2007, 04:48 PM
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Default RE: Controlling PCM servo with switch

The servo requires a pulse width of ~1, 1.5, 2ms to function. one end, center, other end.
you can not just apply a voltage to the input.
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Old 02-18-2007, 05:09 PM
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Default RE: Controlling PCM servo with switch

What you are looking for is a POD pulse omission detector servo --
Futaba had one a few years ago - very good 180 degree. I think number was " 136 retract servo"
but not 12v - and required the std Futaba rf rate.
when tx was OFF-- the servo saw no pulse -went to one direction - Then when you turned TX ON ,-- if--it saw a short pulse. it held that position - then selecting other switch position -LONG PULSE-- it rotated to other extreme end (180 throw). Ithink the servo pot had two tracks -- find one and see if it helps you.
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Old 02-19-2007, 09:38 AM
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Default RE: Controlling PCM servo with switch

here you can find some info about a Servo tester, that can generate the correct signal:

http://www.uoguelph.ca/~antoon/index.htm
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