200mv pulse to 12v lock

[raulthree]

I have a circuit that
produces 2 pulses of (200mv)-(2v) when transitioning to On state
and
produces 2 pulses of (-200mv)-(-2v) when transitioning to Off state

I have would like to use these pulses in the simplest way possible to control a switch/relay/circuit
+12v on state
0 volt off state

the 12v would be powered by a source separate from the existing circuits power source.

 

[danadak]

Whats the drive current available from the pulse generators ?

Driving relay directly from optocoupler, what is best?

I'm designing a smart socket using an ESP-32 and a mechanical relay that can drive 5A at 240VAC. Following typical relay driving circuits, I would like to use an optocoupler between the MCU and rel...

electronics.stackexchange.com

How to Connect a Relay through an Opto-Coupler – Homemade Circuit Projects

www.homemade-circuits.com

Complete circuit diagram of optocoupler driving relay (optocoupler / ULN2803 / switch circuit) - Electronic Paper

Circuit diagram of optocoupler driving relay (1) Note: The 1u1-1 pin can be connected with 12V or 5V. 1u1 is on, 1q1 is on, 1q1-3 is 0V, and the voltage at both ends of coil is 11.7v 1u1-1 pin is not connected or grounded, 1u1 is not connected, 1q1 is cut off, 1q1-3 = 11.9v, …

ee-paper.com

Regards, Dana.

 

[raulthree]

looks like 80-100 mA

 

[raulthree]

So I'm doing some homework on optocouplers now the lowest input voltage I've found is 3v but I feel like this might be the right track. It's just so difficult to find something for those low power inputs.

 

[Nigel Goodwin]

So I'm doing some homework on optocouplers now the lowest input voltage I've found is 3v but I feel like this might be the right track. It's just so difficult to find something for those low power inputs.

I suggest you are more specific, and tell us EXACTLY what the source is - as the wide range you suggest means you need an opamp to amplify it before you can do anything useful. 2V would be no problem, as you could switch a bipolar transistor easily with that - but then there's the confusing positive and negative thing.

 

[raulthree]

I'm getting those numbers with a multimeter. I've measured the voltage as the system goes off and on about 40 times . The non transition voltage is 0. The numbers stated earlier encompass all of the readings.

 

[Nigel Goodwin]

I'm getting those numbers with a multimeter. I've measured the voltage as the system goes off and on about 40 times . The non transition voltage is 0. The numbers stated earlier encompass all of the readings.

You've still told us nothing?. And if you're measuring pulses/AC with a multimeter then it's completely meaningless anyway.

 

[danadak]

Does your multimeter have a AC peak reading function ? If so check its specs
in manual if you can capture 200 mS or less peaks.

If you have a f() generator set it up for 400 ms, 2.5 Hz, 2V and see what your meter reads.

An oscilloscope would be real handy for this measurement.

Use a bench power supply, set your meter to resistance, and connect it to NO contacts on
relay and see what V it energizes at.

These can all give you clues.

Your pulses are 2.2V, most opto couplers input LED turn on between 1 - 2 V, so thats not
an issue. Just limit the input current to datasheet spec allowed. Use a R to do this. Its output
current capability to feed the relay coil you need. And off state voltage on the transistor it
can tolerate.

Something like this -

https://www.qt-brightek.com/datasheet/QT851.pdf

Just go to digikey and use filters to get needed relay current thru output of coupler
and say 2X the 12V in system for output transistor breakdown margin. Transistor output.
100 mA for coil current, although there are many relays << 100 mA to turn on......



Regards, Dana.

 

[raulthree]

danadak thank you so much for pointing me in the right direction. I have two optocouplers in reverse polarity going to a latching relay works perfectly for my situation.