If you selected the relays from the output of a demux, then you could arrange to isolate the FIRST button press from any that follow by disabling the demux right after a button is pressed.

This was the small bit of logic I had envisioned way back at the start of the thread. A bit of timing from a 555(started by button press) and a 4-16 demux would select the relay and using complimetary outputs 15 relays would be reset and one would be set.

 

What exactly does this 'external' 24VAC timer do for your circuit? What function does it perform in the operation, or what does it prevent from happening?

Could the external signal be something other than an AC voltage? If you selected the relays from the output of a demux, then you could arrange to isolate the FIRST button press from any that follow by disabling the demux right after a button is pressed.

This was the small bit of logic I had envisioned way back at the start of the thread. A bit of timing from a 555(started by button press) and a 4-16 demux would select the relay and using complimetary outputs 15 relays would be reset and one would be set.

Kermit2, Ken, & others,

The radio buttons (I also learned this from a small amount of PLC tinkering) --- of course by definition --- need to be "on" only one at a time including the "off" --- this is the roadblock that I kept seeing when I honestly was trying to put together a schematic avoiding all PCB components with the electrical workspace within AutoCAD MEP. To address the Kermit2 Ken's concern --- if 2 or more were on --- it would be a problem. One pole of the latching has to be 24 VAC because all of the 11w solenoids already exist.

Since Ken changed the coils to 12 VDC relays from the less versatile 24VAC ---- it seems like if the 555 could be tweaked so the delays would not be noticeable but still serve the function of making the radio button effect --- it sounds like it could be a winner. Would a 555 complicate the circuit a lot? It would be nice to have the ability to potentially expand to 15 relays as mentioned by Kermit2. Or maybe we would have to go to a few extra relays to accomplish the 12 or 13 relay result needed?

I have used prefabricated reasonably priced multiplexers from an outfit called IDXINC in Arkansas that make one 24VAC output from 8 isolated 24 VAC inputs ---- but we would still have to isolate that output from the specific button pressed. I just checked on their website & I did not see the part listed so --- I am not sure if they even still make that component.

Thanks, everyone for helping to avoid too much ruined material & components from unnecessary re-dooos! I guess it is one thing to modify an editable schematic & another to actually be able to use the G --- word!

Hmmm ----- wun uff dose contracts --- Ken? ---- The email on my extremely low traffic website --- notified me immediately when you sent me the first pass of the specific schematic. I will have to put rev0 or rev1 at the end of its file name ---- in case we come up with something better!

Mike

 

What exactly does this 'external' 24VAC timer do for your circuit? What function does it perform in the operation, or what does it prevent from happening?

Kermit2,

The external 24 VAC timer with a common origin with the always on 24VAC power supply is needed to make sure we have control over when the buttons can not trigger anything. The "off" should be lit up at that time just to show that the interface is not completely dead --- that it is more on standby. Signs would explain how to start & maintain the timer --- so that the buttons would be operational. That particular timer with its 24 VAC in & output power ---- we already have.

Hopefully, that answers that specific question.

Mike

 

I'll give a try at a solution and hopefully keep the part count low. I'm not fast.

 

Here's radio button part of a circuit I used once. Worked well. The down side is you need N*(N-1) steering diodes. For 13 buttons that's a 156 diode array.

Another option, by elbc1388, from another radio button circuit thread. I just can't get my head around doing it with cascading two 4017s. http://www.electro-tech-online.com/electronic-projects-design-ideas-reviews/37789-radio-button-relays.html#post297419

Ken