I am literally pulling my hair out.
A week ago I decided I needed to control two circuits of 120vac low amperage
(less than 500ma) with a single pushbutton. I have a tactile type button beneath a plastic membrane (like your cell phone) that I can use to relay these circuits from bothon/bothoff. Suffice it to say that I have no options at the user control point. I cannot use a dpdt pushbutton on the panel. I have to use a single momentary to toggle power dpdt style.
I saw immediately that a dpdt relay would be necessary, with a low enough voltage/amperage on the coil to operate it with the pushbutton. Ok so far. Then I went to Digikey to get a relay that would alternate, and latch, using the pushbutton..... the same pushbutton. Push on... push off.
Within a few hours I was seeing stars. I'm told by many experts that this cannot be done without microprocessing. The only other options are expensive and extremely bulky industrial relays rated from 30 to 100 amps.
But I can actually accomplish this myself with a little 12vdc push solenoid and a dpdt latching pushbutton! I hate like hell to have to cobble something this ugly together. I'm F L A B B E R G A S T E D that this is such an impossible feat to accomplish. I sit with a pencil and paper and try to get three dpdt dual coil latching relays to do this by bouncing off of one another and all i get is a headache and bad memories of the logic section of the LSAT! Why can't I buy this? Waaaaaaah. I'm going to cry like a child pretty soon.
I've found flip flop pcb units that almost do what I need. They are too complex and, more importantly, lose their status upon deenergizing (requiring another layer of complexity with diodes and batteries to keep 'memory' on the circuit).
As well as losing the last 'condition' of the relay if I use cmos, 555 timers, et al, I really need a purely electromechanical solution since this is going to be used in a welding project that will be exposed to extreme HF at times. That does funky stuff to homemade circuits.
I've actually talked with no less than half a dozen engineers at the major relay manufacturers and they've all seemed pretty stumped as to why I'd want to do this. I feel like I landed on another planet. The web is chock full of posts from people trying to accomplish this with rube goldbergian spagetti messes of relays, connectors, diodes, transistors, etc, etc.
So picture a small barrel type solenoid acuator.... 12vdc coil..... depressing a dpdt latching microswitch.... and this inside of a little plastic cube that is pcb mountable. Does anyone manufacture this thing??? A volkswagen headlight relay does it. It's 12vdc. But it's bulky, way overrated contacts for my needs, and only spdt. I'd have to add another relay to it yet. Another messy solution.
Please, dear god, help me. If you guys can lead me to the light you will be superheros and will have stumped all the "experts" on top of it.
Thank you. I'll calm down now and take a few steps back. I'll have a beer. I'll be back tomorrow on tenter hooks...
A week ago I decided I needed to control two circuits of 120vac low amperage
(less than 500ma) with a single pushbutton. I have a tactile type button beneath a plastic membrane (like your cell phone) that I can use to relay these circuits from bothon/bothoff. Suffice it to say that I have no options at the user control point. I cannot use a dpdt pushbutton on the panel. I have to use a single momentary to toggle power dpdt style.
I saw immediately that a dpdt relay would be necessary, with a low enough voltage/amperage on the coil to operate it with the pushbutton. Ok so far. Then I went to Digikey to get a relay that would alternate, and latch, using the pushbutton..... the same pushbutton. Push on... push off.
Within a few hours I was seeing stars. I'm told by many experts that this cannot be done without microprocessing. The only other options are expensive and extremely bulky industrial relays rated from 30 to 100 amps.
But I can actually accomplish this myself with a little 12vdc push solenoid and a dpdt latching pushbutton! I hate like hell to have to cobble something this ugly together. I'm F L A B B E R G A S T E D that this is such an impossible feat to accomplish. I sit with a pencil and paper and try to get three dpdt dual coil latching relays to do this by bouncing off of one another and all i get is a headache and bad memories of the logic section of the LSAT! Why can't I buy this? Waaaaaaah. I'm going to cry like a child pretty soon.
I've found flip flop pcb units that almost do what I need. They are too complex and, more importantly, lose their status upon deenergizing (requiring another layer of complexity with diodes and batteries to keep 'memory' on the circuit).
As well as losing the last 'condition' of the relay if I use cmos, 555 timers, et al, I really need a purely electromechanical solution since this is going to be used in a welding project that will be exposed to extreme HF at times. That does funky stuff to homemade circuits.
I've actually talked with no less than half a dozen engineers at the major relay manufacturers and they've all seemed pretty stumped as to why I'd want to do this. I feel like I landed on another planet. The web is chock full of posts from people trying to accomplish this with rube goldbergian spagetti messes of relays, connectors, diodes, transistors, etc, etc.
So picture a small barrel type solenoid acuator.... 12vdc coil..... depressing a dpdt latching microswitch.... and this inside of a little plastic cube that is pcb mountable. Does anyone manufacture this thing??? A volkswagen headlight relay does it. It's 12vdc. But it's bulky, way overrated contacts for my needs, and only spdt. I'd have to add another relay to it yet. Another messy solution.
Please, dear god, help me. If you guys can lead me to the light you will be superheros and will have stumped all the "experts" on top of it.
Thank you. I'll calm down now and take a few steps back. I'll have a beer. I'll be back tomorrow on tenter hooks...
Last edited:
(Bill, shame on you!)
