I built your circuit. I ran it from 12 V instead of 9 V and I don't have your sensor. When I touch the point where the sensor goes with my meter the LED blinks once. Is that what it is supposed to do, or is it supposed to blink continually? On power on I get one blink. It does the same thing at 5 V.

I believe it's supposed to light up/buzz for less than a second, then go off.

 

I believe it's supposed to light up/buzz for less than a second, then go off.

Then the circuit is good.

 

Each input pulse from the sensor should produce a respective brief (<1s) buzz/flash.

 

Each input pulse from the sensor should produce a respective brief (<1s) buzz/flash.

Then the design is good.

 

I built your circuit. I ran it from 12 V instead of 9 V and I don't have your sensor. When I touch the point where the sensor goes with my meter the LED blinks once. Is that what it is supposed to do, or is it supposed to blink continually? On power on I get one blink. It does the same thing at 5 V.

I simulated the circuit in post #32 and it behaves exactly as you described.

But I am now away from home with my family and don't have all the program tools and bandwidth to give further help.

Allen

 

Thanks for all your input guys, especially absf.

I stripped it down and used new components and its working exactly as it should, I think one of the components may have been damaged in the initial setup when I didn't have it hooked up properly, its all good practise though!

 

Good Job!

 

Well done.

 

Out of interest, is it possible and if so, how easy would it be to add something to that circuit whereby no indication is given off when the sensor is activated for a second?

Basically the application I'm trying to use this in, it only requires indication if there is a steady flow of vibration, not just for the occasional knock.

 

Out of interest, is it possible and if so, how easy would it be to add something to that circuit whereby no indication is given off when the sensor is activated for a second?

Basically the application I'm trying to use this in, it only requires indication if there is a steady flow of vibration, not just for the occasional knock.

So you only want it to alarm if the sensor is set off more than once in a certain period? How many times in what period?

 

So you only want it to alarm if the sensor is set off more than once in a certain period? How many times in what period?

Say after 2-3 times or after 2 seconds, not for long, just to allow for a false indication.

 

Say after 2-3 times or after 2 seconds, not for long, just to allow for a false indication.

Timing components haven't been selected yet. A short timer, that is resettable, and a long timer. If the short timer is still set when the long timer times out it registers an error. I haven't built it yet.

Oops, I noticed a problem. Get back to you in a minute.
(edited to correct drawing)

 

Timing components haven't been selected yet. A short timer, that is resettable, and a long timer. If the short timer is still set when the long timer times out it registers an error. I haven't built it yet.

Oops, I noticed a problem. Get back to you in a minute.
(edited to correct drawing)

Corrected schematic. Short time timer has been set to about 0.2 seconds and the long time timer to about 2 seconds. If the short time timer is still set when the long time timer times out it registers an error. (In theory).

 

Thats really helpful, thank you. I'll take a look