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DC Polarity Shifter / changer Answered

Require assistance to build a device to change the polarity of 13-14 volts 30 amps with an adjustable timer. Any help would be appreciated.


The interval needs to be adjustable becuase we don't know what will be the most efficient for our operation. Once we have determined what the interval is no further adjustment would be required. The interval would be regular at say 5 seconds positive negative then 5 seconds negative positive but for the same duration both ways. The timing doesn't have to be 100% accurate as no harm will be done if it is slightly out. No external control is required after it is set up. Thanks for your patience.

Then a simple discrete timer circuit will do. I suggest you search here (or google) for "555", which is an inexpensive timer IC. The duration and symmetry of the pulse can be easily adjusted with a few extra components. Search "555 relay" and you'll find fully documented circuits. As in the link I posted earlier, you should note that relays produce inductive spikes when transitioning between states, so some sort of "protection diode" is required. But all the 555 + relay circuits should mention this...

Sorry a little sketch but electronics is not my area of expertise. I understand I can use a DPDT relay but need an adjustable circuit to trigger it. Guess this is where I need help. I diagram of what you believe I need would be appreciated.

A little more detail would be helpful--what sort of timing interval, and is it a regular interval or complex? Switching speed? Is some sort of external control required? That kinda stuff...


9 years ago

Your description's a little sketchy; the simplest way is a DPDT relay. This link might be helpful, as far as a driver circuit (protection diode, etc.)

Do you have the timer already?