Relay Logic

[The Anonymous]

Maybe I should have said Geek?

Shut the Fuck UP!

[uscitizen]

Here's the chain of events.

In a small interview room, there is a duress button in case the interviewer feels threatened.

The button gets pushed, causing a piezo and a strobe light outside the door, as well as strobes throughout the office to turn on. It also powers up a led in a push button outside the door. When the interviewer exits the room and pushes that button, the door strike powers up and recedes, thus locking the door and the led in the push button turns off. The strobes and piezos continue to be active. Once the situation is rectified, a key is used to reset the duress button, at which point the entire system goes back to normal.

The duress button is simply a normally open latching contact.

It took me some time to figure this out, but it was good to finally get it. The key is that pushing the duress button is one half of the double throw relay firing, and the push button is what actually energizes it. Here's a little twist too. There are two rooms that were there to begin with with this system, but none of the wires were labeled and the relay was totally different, rendering it impossible to simply copy, and I had to add two new rooms. But each room had to fire the strobe only outside its door and ones on the ceiling throughout the office. I used two RIBs to do this.

Don't you just love having to figure out how something works so you can either repair or expand it?