slightly OT, need some electronic circuit help
torriem at gmail.com
Mon Oct 8 15:36:15 MDT 2012
On 10/08/2012 03:18 PM, Shane Hathaway wrote:
> Ok, it seems like you want 2 op-amps wired as comparators. One op amp
> decides whether to move the motor forward, the other decides whether to
> move it backward. (You can get multiple op-amps on a chip, so this
> doesn't increase the parts count.) You'll have to calibrate the circuit
> so that the op amps don't activate simultaneously.
> To keep things simple, let's say each op amp drives a DPST (or DPDT)
> relay. That solves your voltage issue: it isolates the control circuit
> from the motors, so you can apply reverse voltage to the motors. You
> can also use a voltage regulator in case the supply is too noisy.
Good to know I'm on the right track. I was thinking along these very
lines in fact just when I noticed your e-mail.
> Each op amp should perform a slightly different comparison. When you
> want the middle position, the op amp that controls forward movement
> should compare the motor sense voltage with a voltage slightly lower
> than the control voltage, while the other op amp compares the motor
> sense voltage with a voltage slightly higher than the control voltage.
> You can adjust the voltages using resistor-based voltage dividers.
> Does that make sense? The comparator circuit on this page is a good
Absolutely makes sense! This is the track I'm heading down. Thank you
very much for your thoughts on this. I knew there had to be a
relatively easy way of accomplishing this.
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