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From: jfischer@knife.cs.umn.edu (John D. Fischer)
Subject: Re: Voltage Controled Resistors?
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Date: Fri, 10 Feb 1995 19:57:23 GMT
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|>   Thanks for your suggestion. I have more than 1 joystick
|> to control with say a Stamp. Now I'd have to go into a big loop
|> generating PWM signals to different outputs as fast as possible
|> otherwise the servos would swing back to where the joysticks  tell
|> them to point if you do not remove the wires from the pots.

Are you trying to control a servo directly?  If you are trying to
replace the joysticks on the hand held controller you don't need
to use PWM you only need to update the two D/A converters.  You will
only need to update the D/A's when you want to change the angle of the
wheels or change the speed of the car.  PWM is used to controll the
servos directly.

|> 
|> Also with pots that use 3 wires, I'd really be having a hard time
|> as there will be 2 points for each pot.  I need to control 2 pots
|> at a time.

Most pots have 3 wires.  Only the middle one is the signal.
|> 
|> With a digitally controlled resistor, there is hopefully a latch
|> inside to fix the resistance so that when the ics are not
|> being accessed, they won't go nuts and the servos would stay
|> where they last were..

The way you are going to hook-up the resisters is going to produce
an output that is exactly identical to a D/A converter.  Except there
is a ton of information on D/A converters and most electronic stores
will sell them.

|> 
|> Correct me if I am wrong.. I think this way the coding is less
|> hectic/ I'd appreciate you correcting me if I am wrong..
|> 

I hope this helps.

John
