Sequential dual DPDT relay from single trigger source

Thread Starter

genner

Joined Jan 29, 2019
13
Hello Everyone,

Not sure if this exists as a premade circuit module already but I need help making two relays trigger one after each other back and forth everytime the circuit is energized with 12 volts.
I hope this makes sense but the idea is when the circuit senses 12volts, Relay A will trigger and remain triggered until the 12 volts is turned off. When the circuit senses 12volts again, Relay B will trigger and remain triggered until 12volts is turned off. And then back to triggering Relay A when 12 volts is sent to the circuit.

Any information would be a great help!
 

Thread Starter

genner

Joined Jan 29, 2019
13
Hello crutschow, thanks for replying.

I could technically add another power source if needed to power this sequential relaying circuit. If possible I'd like to avoid that but I am thinking I might need it after all to keep some sort of memory of the last state of which relay was triggered. However the power source of 12V that energizes the relay will be periodic.
 

crutschow

Joined Mar 14, 2008
23,732
Well you could likely do the memory with a couple of latching relays and avoid an added power supply.
 
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LesJones

Joined Jan 8, 2017
2,414
What is the maximum time the 12 volts will be off. I am thinking it may be possible to charge a capacitor or keep a rechargeable battery battery charged to power some cmos logic during the off time.

Les.
 

Thread Starter

genner

Joined Jan 29, 2019
13
Hello Everyone thanks for helping me.

Yaakov, those are interesting Bistable DPDT relays where it stays at the last state even when the power turned off. I didn't know those even existed.

My apologies I guess I should have given a bit of a background on my project.
I have this alarm system that can output a trigger of 12v or gnd. The duration of this trigger can be programmed to have a 2 second delay, close and stay closed, or pulse 1 second on and 1 second off. My idea was to use the 2 second delay and use the 12V trigger to energize a dpdt relay, two of them sequentially somehow....
What I have is a deadbolt rod that I would like to automatically slide into place when I activate the trigger through the alarm's keypad.
I currently have a high torque worm gear that can drive this rod back and forth. I also have this reverse/forward timer motor controller module,
The goal is when I activate the trigger, the worm gear setup will move this rod into locking position and stops when it hits an external limit switch. Then the next time I activate the same trigger through the alarm panel, it will reverse the worm gear and pull the deadbolt rod backwards and when the deadbolt hits the second limit switch it will stop.

I was initially thinking that i can utilize the 12V from the alarm panel trigger to first energize Relay A so that it will short the FWD terminal with ground on the timer motor module and send the motor forward. When it reaches the limit switch, it will short the STOP terminal.
Then the next time I trigger the same 12V pin output from the alarm panel, it should then energize Relay B and that will short the REV terminal on the motor timer module and when going reverse hits the second limit switch, it will also short the STOP terminal.
I surely hope my project makes sense. Also I hope I am approaching my project logically but please help guide me in the right direction as I could be complicating something that is super simple.

Thanks for helping everyone!
 

sghioto

Joined Dec 31, 2017
1,038
I don't think you will need any relays as it appears the three inputs FWD, REV and STOP are isolated using
optocouplers. Since power is available there should be multiple ways of accomplishing your goal. The easiest method would be to use a microprocessor, but analog solutions are available. From what I have read about this timer you shouldn't need any limit switches either.

SG
 
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Thread Starter

genner

Joined Jan 29, 2019
13
Hello sghioto, the thing is I'm not sure how I would use the single 12V trigger from the alarm panel to send the FWD signal and then later the REV signal to the motor. Like how will this timer motor module know what state the deadbolt is at in order to FWD or REV the motor. The only thing I've got is just triggering the 12V output from the alarm panel only. I guess this part I can't figure out.
 

Yaakov

Joined Jan 27, 2019
1,610
If you use a multi pole limit switch you can allow it to determine where the control signal goes, routing it to the close contacts when not activated and to the open when activated,

But, Your design really needs a some smarts to supervise the action in case of mechanical failure and some kind of manual override that doesn’t depend on power.

And, you don’t want to run things open loop, that is, without sensor(s). Depending on timing is very weak design that can fail in all sorts of ways.

If you have two limit switches, open and closed, you increase reliability and control, and you also solve your bistable problem mechanically.
 

Thread Starter

genner

Joined Jan 29, 2019
13
Hello Yaakov, thanks again for the assistance. Yes I don't plan on using the timer to actually stop the worm gear from turning I mostly bought this timer motor module for the FWD/REF/and STOP input and the FWD/REV motor capability.

So I found this circuit
beginning at 1:06 is sort of the function that I am looking for but with a setup of only two relays needed. In theory from these two relays, when energized, it will "short"(gnd) the fwd and rev input triggers on the timer motor controller respectively. In the video where the push button is being pressed to activate the sequential relays, that would be input from a simple spst relay controlled by the 12v tigger pin from the alarm panel.

Does anyone know how to build a dual relay version of this circuit? I tried looking it up but I am super clueless about the IC chips that are being used.
 

Thread Starter

genner

Joined Jan 29, 2019
13
Hello sghioto, the time from unlocked position to lock position should be around 4 seconds, the rod is traveling about 4 inches into locking position.

eetech00, if i understand the monitor correctly, upon closing the trigger switch in the circuit, the relay that triggers REV will be energized first? Then, once the trigger is opened, the relay that triggers FWD will energize?
 

MisterBill2

Joined Jan 23, 2018
4,472
Limit switches monitoring the position of the deadbolt are a good idea, because the time to move may vary depending on friction and wear.
Usually alternative actions from a single output are a poor choice simply because it is easy to lose track of what comes next. But there are also a number of different mechanical relay devices that will provide the action that you want. There used to be a reversing relay used for model train operations that would give alternating forward and reverse modes, as one example.
 
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