Hold to change state.

Thread Starter

terrelui

Joined Mar 26, 2023
2
Hello, electronics are still fresh waters for me so apologies in advance.

Im looking for a certain kind of time relay or something similar that has COM and NC dry contact that will not change state unless something is pressed down for a set amount of time (lets say 30 seconds), If it is released before set time it will not open/release contact.

For reference : (DE = Delay Egress)
Working on a crash bar that has COM,NC,NO contacts. crash bar needs to activate delay egress on a mag lock if it is held for 30 seconds. The issue I have is the maglock will activate DE when contacts it has are opened , It has a nuisance delay option but it only goes up to 3 seconds. The reason it has to be 30 seconds is because the door is capable of engaging the crash bar and opening when someone unlocks it using a code tied to a small makeshift access control box. There are no more points left on it so we are having to make shift some more. The crash bar being held during the unlock time can have no affect on DE point on maglock. The crashbar must be engaged when for longer that 30 seconds to activate DE timer.

hope this makes sense, will add drawing of what im thinking since my english is horrendous.
The relay currently on the drawing (with yellow trigger) was what i thought i originally needed until i realized data sheet said it would start release timer as soon as it was triggered.
 

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crutschow

Joined Mar 14, 2008
34,430
So if the relay triggers only after 30s, how is the relay again released?

A 555 timer configured for a 30s delay, driving a small relay should likely do what you want.
 

Thread Starter

terrelui

Joined Mar 26, 2023
2
So if the relay triggers only after 30s, how is the relay again released?

A 555 timer configured for a 30s delay, driving a small relay should likely do what you want.
I would like the relay to go back to NC/release a little after being triggered, it will need to stay closed to not activate the DE on maglock once it gets reset.
I found this while doing some digging, do you think this would do the trick ? Someone said what I'm looking for is a "delay on make relay"

https://jmacfiles.s3.amazonaws.com/TDM-InstallationManual.pdf
 

crutschow

Joined Mar 14, 2008
34,430
I found this while doing some digging, do you think this would do the trick ? Someone said what I'm looking for is a "delay on make relay"
After a cursory look, that would appear to work.
Make sure it does the exact sequence you want.

Otherwise I can gin up a circuit using a 555 timer and a relay, if you like.
 

MisterBill2

Joined Jan 23, 2018
18,502
A simple timer module, operate after delay, will work. Those modules are available tboth mains powered and also 24 volts powered, either AC or DC. The benefit of using a TIMER MODULE IS NO ELECTRONICS FABRICATION REQUIRED, and it is already packaged. Also, different time ranges are available.

Please note: A "Crash Bar" is what is added to a motorcycle to protect the engine and rider if it tips. The bar on a door to unlock it is usually called a "panic bar" because it will allow the door to open if a crowd pushes against it.

I see a setup like described in many stores: press the bar and an alarm will sound for 30 seconds and then the door unlocks. That scheme is implemented to prevent thefts while allowing an emergency exit i case of fire.
 
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