Re: Alternating relay


Ryan wrote:
> Is there a stock item which directs voltage onto one wire the first
> time it is given power, and then to another wire the second time when
> the item is given power?
>
> I have two air compressor units tied together as one tank. Right now,
> only one of the pumps is hooked up.
>
> The pressure switch is pneumatically closed/opened. The contacts of
> this switch power the motor on directly.
>
> I would like to introduce a contactor that, when given this on signal,
> will power on pump #1 for that cycle and then shut it off when the
> pressure switch is disengaged. Next time air is low, I want a
> contactor to engage pump #2 for that cycle and then turn off the motor
> when it is powered off by the pressure switch.
>
> Back and forth at infinitum so the load is distributed evenly over time.
>
> The only "alternating" relays or contactors I have found require
> either separate on signals (one for each coil) or else reverse
> polarity in a single coil. I have only one signal: the on / off
> state of the pressure switches contacts.
>
> My local electical supply houses are either dumbfounded to
> speechlessness by my request, or else don't have anything to fit the
> bill.
>
> With that having failed, I wonder if there are stock electronic
> circuits that exist, or that I could fashion, and then relay that
> signal into larger switching gear without having to invest in a rocket
> science degree first. (Perhaps I could use a doorbell transformer
> or something easily found to power the coils and maybe the small
> electronics too.)
>
> The circuit would perform like this:
>
> Source Off = Motor1 off Motor2 off
> Source On = Motor1 on Motor2 off
> Source Off = Motor1 off Motor2 off
> Source On = Motor1 off Motor2 on
> Source Off = Motor1 off Motor2 off
>
> I'm stumped.
>
> -Ryan

I used an alternating relay once that had a single coil. When
actuated, the solenoid pulled on an alternating mechanism with two
latching positions, which would reverse every time you actuate the
coil. Run the motor off the contacts of the alternating relay. This
way you could switch motors every time the pressure switch turns on.
Of course the motor would stay on even after the pressure switch turns
off. You would still need a way to turn the motor off when the
pressure switch turns off, but it's easy enough to put an ordinary
relay in series with the alternating relay.

.

Relevant Pages

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