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| How Do I Convert DC Motor To Reverse With SPDT Switch? |
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| andyf:
Here's my contribution, based on John's first drawing and taking into account that your existing dashboard switch is momentary. Giving it a quick flip up or down will energise one or other of the relay coils. When the relay contacts close, +12v from the motor supply is fed back to the coil, holding it on until the limit switch opens, breaking the feedback so the relay switch opens and the motor stops. If I've made some ghastly error, someone please correct me! Andy |
| Bluechip:
Bottom rail S/B 0V .. :thumbup: ( Pedantic pillock ... nowt on the telly ... AGAIN :lol: ) BC |
| John Swift:
Hi Andy , the only problem I can see is if you selected a motor direction and then selected the reverse before it reached the limit switch and the first relay dropped out both relays would be latched on and the motor stopped between the two limits sod's law predicts it will happen sooner or later you need to be able to switch off the 12v supply to the relays to reset the circuit or use two pole relays to interlock the relays to prevent this John circuit added |
| andyf:
Good point, John. Sod's law* would leave my version connecting both motor terminals to +12v, so it would stop, leaving the headlamps stuck halfway up and both relays latched on until the "+12v Motor Supply" was broken momentarily. More thought required. Andy * For the benefit of our US cousins, Murphy has a close relative called Sod who also fouls things up, but whose name isn't mentioned in front of the children. |
| snub:
Holy Cr*p....You guys are fantastic. I had a feeling that this would be the best forum to ask this question. But stupid me, I just spent an hour trying to convert John Swifts excellent schematics into a diagram, I click on here and he's already done it. Ah, what the heck. I'll post it up anyways. The only thing different ( that I can see), is that I have power going into terminal #30, and out of #87. I'm guessing it doesn't make a difference as it's only a 'switch'. Thanks again for all your help! |
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