Momentary Contact Switch with Latching LED Status Indicator Pole Sought

[SDG]

We need to momentarily activate a contact closure circuit (pulled up via 10K resistor) while having a second pole on the switch that latches an LED status light power circuit until the next time the momentary contact is made.

Each time the momentary contact is activated, we need to alternately energize and deenergize the LED status circuit. Is there such a switch available out there as one integral unit, either as a toggle lever arm type or a depress type?

 

[KJ6EAD]

I've never seen a switch that had both momentary and maintained contacts via the same actuator. There are ways to toggle an LED on and off from a momentary switch. If you're trying to indicate the status of the other controlled circuit, that could be done directly instead of depending on two switches staying in synch.

 

[SDG]

The controlled circuit that the momentary contact interfaces with is a wireless transmitter that in turn sends an encoded command to a remote receiver. This receiver then opens or closes a power management relay on the remote device in a toggle mode of operation.

Therefore, we do not have physical access to the end-item controlled circuit and instead have to "settle for" an indication light that could admittedly get out of synch compared to the momentary transmit pulse circuit. However, we'll have a simple inline toggle switch as both a safety interlock as well as to disconnect the transmitter from the control panel if we have to resynch the status situation.

 

[djsfantasi]

Can you use a standard switch that triggers a 555 mosostable circuit to send a single pulse when the switch is thrown?

 

[SDG]

So perhaps rig a normal toggle switch with one of two parallel branches for the 555 circuit and the other for an LED indicator? That way the transmitter is momentarily activated like we need it to be when the switch is thrown but the LED stays lit afterward?

But we also need the transmitter to send another wireless signal (same command actually) to toggle the power relay of the remote receiver back off when we deactivate the switch (and also turn off the LED). How would we accomplish that?

Perhaps use a DPDT switch and connect both the NO and NC sides to hook back into the same 555 circuit? But we'd get an unwanted pulse from the transmitter initially upon power up... unless we power up first with a separate safety interlock switch open and then throw the interlocking switch afterward. The safety interlock would be a simple inline SPST toggle before connecting to the transmitter. This make sense?

 

[djsfantasi]

OK, so I didn't think it out too clearly. I have another "idea". With the momentary pushbutton switch, trigger the 555 to send the wireless signal and a flip-flop to drive an LED, indicating state... You will need to debounce the switch and need some extra components to drive the LED from the flop-flip.

 

[SDG]

dj... excellent idea. One of our guys also came up with this approach using a J-K flip-flop to drive the LED. In the lab this afternoon, he already got it working with a momentary contact switch as the trigger. Our transmitter has debounce circuitry on the switch connection already, so we're covered on that score too.

I think we'll go this route and just replicate it on the control station box for the 5 different control channels we need to manage this way. btw, this is for a remote control box for a flying robotic vehicle with thrusters... so this'll be loads of fun when we get it all running. I also like the idea of adding the interlock switches anyway as a level of extra safety against inadvertent commanding. I'll pick some of those Lift-to-Toggle types with the levers that have to be lifted up over the center lock-out cam area.
thx for your suggestions!