Sound activated dry contact switch

Thread Starter

saxguy

Joined Sep 24, 2017
7
I would like to know how to make a circuit that will close a dry contact (small relay) for maybe around 200ms to 500ms or so, on hearing a loud noise (with sensitivity control). Preferably with a small lead mic, that can be positioned to suit, away from the PCB.

There are many sound activated kits available, but basically I need one that is just for a “dry pulse” trigger, with a low latency, which will then be used for a PLC input. Most are latching, or have long "on" periods. I will have a 24v (not sure either AC or DC supply) for the plc, so if the circuit could be powered by the same, it would make things easier.

I’m not an electronic buff, but can solder/construct, if I know which components to use. I would be so grateful for any help on this, as I have tried for ages elsewhere to find this info, to no avail.

Thank you so much.
 

Thread Starter

saxguy

Joined Sep 24, 2017
7
What is a "dry contact" or a "dry pulse"?
By this I mean a normally open contact (like a relay contact) that closes when the circuit is activated. Dry, means it has no actual output (voltage), but just acts as a switch. By pulse, I mean it isn't latched. It basically stays on (active) for a brief period, ie "pulse". Like a momentary switched relay.
Thanks
 

AlbertHall

Joined Jun 4, 2014
10,536
Can you check what supply voltage you have available and whether it is AC or DC, please?
That is the biggest change required to make this work for you.
 

Thread Starter

saxguy

Joined Sep 24, 2017
7
Can you check what supply voltage you have available and whether it is AC or DC, please?
That is the biggest change required to make this work for you.
Hi, I'm not sure yet, but, I am going to be using PLC's and pneumatic rams (with solenoids), and I have been informed that the industry standard is usually 24v, as there is more readily available equipment in 24v. However, I'm not sure if this will be AC or DC, as I forgot to ask (doh!). I would say however that if we consider it to be 24v AC, as adding a simple rectifier if require, isn't much of a task.
I do have some basic underpinning electrical knowledge, as I am a qualified electrician, however, electronics I have never really delved into.
I have just found a simple circuit on you tube which might be what I'm looking for ie
which I guess would only need a simple voltage reg of some sort from 24V down to 9v. I would be interested if anyone has a comment on the you tube video. Thanks again guys.
 

Thread Starter

saxguy

Joined Sep 24, 2017
7
Hi, I'm not sure yet, but, I am going to be using PLC's and pneumatic rams (with solenoids), and I have been informed that the industry standard is usually 24v, as there is more readily available equipment in 24v. However, I'm not sure if this will be AC or DC, as I forgot to ask (doh!). I would say however that if we consider it to be 24v AC, as adding a simple rectifier if require, isn't much of a task.
I do have some basic underpinning electrical knowledge, as I am a qualified electrician, however, electronics I have never really delved into.
I have just found a simple circuit on you tube which might be what I'm looking for ie
which I guess would only need a simple voltage reg of some sort from 24V down to 9v. I would be interested if anyone has a comment on the you tube video. Thanks again guys.
I meant to add, I could just maybe add a small relay in place of the LED (or in parallel) to give me the dry contact could I not?
 
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