I need a little help here, I have a latching relay (Omron MJN2CK-DC24) and I need to implement a reset for a vision camera. The unlatch I have working fine but the output from the camera is a constant 24vdc and I need something to break that constant voltage or if there’s another route I can go with this. It’s switching a tower light on and a N.C. 120v circut to run a conveyor. Any help would be appreciated.

 

This is the data sheet for your family of latching relays. The relay uses a center tapped coil with a latching and unlatching side. The coil voltage is applied for about a 1 second duration to latch or unlatch at the coil voltage. So if you are looking to just pulse the coil to latch or unlatch I would think about a commonly called One Shot circuit with a one second duration. You trigger the one shot and it will output a pulse of one second duration to latch or unlatch your relay. How exactly did you want to go about doing this? It can be as simple as holding a normally open push button down for about a second manually or a electronic approach using a one shot.

Ron

 

This is the data sheet for your family of latching relays. The relay uses a center tapped coil with a latching and unlatching side. The coil voltage is applied for about a 1 second duration to latch or unlatch at the coil voltage. So if you are looking to just pulse the coil to latch or unlatch I would think about a commonly called One Shot circuit with a one second duration. You trigger the one shot and it will output a pulse of one second duration to latch or unlatch your relay. How exactly did you want to go about doing this? It can be as simple as holding a normally open push button down for about a second manually or a electronic approach using a one shot.

Ron

The problem that I’m having is my latching source is a constant 24v so when I want to unlatch it’ll get the momentary power to do so but go back to being latched. I need a way to break the constant 24v going to the latching side until it gets another pulse to latch. Or possibly a way to turn the constant 24v into a one shot.

 

The problem that I’m having is my latching source is a constant 24v so when I want to unlatch it’ll get the momentary power to do so but go back to being latched. I need a way to break the constant 24v going to the latching side until it gets another pulse to latch. Or possibly a way to turn the constant 24v into a one shot.

Yes but we need a way to place the one shot inline and trigger it. The relay you have is designed to be pulsed to latch it and pulsed to unlatch it. They make one shot timer modules which will give you what you want. Right now you have a constant 24 volts. All you want or need is a single 24 volt pulse having about a 1 second duration. The problem is what to use as a trigger to initiate the pulse. A Google of One Shot Relay Module or Single Shot Relay Module should bring up a dozen hits. The problem is what to use as a trigger. Also while I am not sure about the specific relay you have the constant application of 24 volts on the latching side of the coil may not be good for the coil if designed for just an intermittent pulse.

The problem will always come back to how to trigger the thing. Got any ideas?

Ron

 

I miss worded that, the constant 24v is put out when the camera reads as “no good” once it reads as “good” again the 24v is removed so I should be able to use that as a trigger? Then just run a separate 24v line through the one shot timer so I can get the pulse to latch the relay?

 

To achieve a momentary pulse from when a DC voltage switches on, use a series capacitor in the DC line. Probably 10 or 47 microfarads at 50 working volts will trigger the relay and then allow a reset. You may need to have a resistor across the capacitor to discharge it before the next pulse arrives. Try 10K ohms for a start The capacitor should do the job very well..

 

It's still not entirely clear when you want the pulse to occur.
Is it when the 24V appears or when the 24V goes away?

From post #5 it sounds like when it goes away.
Below is the LTspice simulation of a simple circuit using a P-MOSFET to generate a ≈200ms pulse (50ms minimum recommended) to the relay coil when the input 24V goes away.

 

If the constant output of the camera is the wrong logic sense, then just a simple relay can easily reverse that problem. The very big benefit of really logic is that it is easily understood by maintanence people all over the world, and it is easy to understand and watch exactly what is happening. And relays of some kind are available almost everywhere.