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(Hopefully) a simple problem

I have a simple drive system for a home-made robot. It used 2 windshield wiper motors and a 12V battery. I have 4 relays under computer control (NC, GND, NO) and I'm trying to design a circuit to apply forward and reverse voltage to each motor, giving maneuverability.

Trouble is I can't design the circuit using a single 12V battery, using two and creating +12V and -12V makes it easy - but this means that the forward battery will drain faster than the 'reverse' battery.

Is it possible to do this with just 1 battery and the relays?

Reply to
kasterborus
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How about....

1 relay interrupts the 12V supply for motor on/off control. Another DPDT contact relay does the battery polarity reversal for forward/backward control. D from BC
Reply to
D from BC

Search for "H-bridge". It's a standard problem, with a standard solution.

Try not to connect battery + to battery - too often.

--

Tim Wescott
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Reply to
Tim Wescott

Yes you can use 2 spst relays for each motor and reverse the polarity:

both NC to minus both NO to plus OP to motor

both relays on or off no motion ry1 on fwd ry2 on rev.

Dave

Reply to
CheapscateDave

Use two relays for each motor, one on each motor lead, connected so that when the relays are not energized, they connect their motor lead to ground, and when they are energized, they connect the lead to the positive supply.

With this scheme, when the relays are not energized, both motor leads are grounded, so it doesn't move. When one relay is operated, its lead goes to +V, and the motor turns one way. Operating the other relay will make the other lead +V, and the motor will turn the other way.

If you happen to energize both relays together, both motor leads will be at +V, and again, it won't move.

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Peter Bennett, VE7CEI  
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Reply to
Peter Bennett

Do you have some spare sperm to donate? I'm being obtuse here to avoid the possibility of alerting my competitors to your existance.

DNA

Reply to
Genome

And use relays with a break-before-make contact configuration...

Chris

Reply to
Chris Jones

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