Problem with VM-Clap1 Sensor and digital output

Hello, I try to use the VM-Clap1 Sensor to turn on and off a led.

While I was building this it seem to worked fine.
But if I unplug the arduino and plug it in again the LED is just glimming and not turning on and off.
I have to unplug the 3V wire and plug it in again. Then it works fine.

I’m sorry if it’s an easy question and I could figure it out myself but I wasn’t been able to do that yet. Would be nice if anyone has an idea and could point me in the right direction what I’m doing wrong.


If you read the component description and the sheet I have attached below, you will find it will work on 5V.
Try it and see if your problem is fixed.

Tom… :slight_smile:

VM-CLAP1_Hand_Clap_Sensor.pdf (77.3 KB)


thanks for your answer. But that's not the problem. The operating voltage from 2.5 V to 5.5 V and working fine.

I'll explain it a little bit better:

The LED is connected to D5 and Ground.

The Clap Sensor is connected to D6, 3V and Ground.

There is also a connection between the clap sensor output and the 3V power with a 10k resistor due to this:

Since the output pin is open collector, an external pull-up is required to make it high by default

Szenario 1:

  1. Everything is connected
  2. I plug in the USB cable
  3. The clap sensor boots and works, the LED is glimming (not really on, not really off)
  4. If I clap I can see the clap sensor recognize it but nothing happens to the LED, it's still glimming

Szenario 2:

  1. LED is connected, clap sensor is not connected
  2. I plug in the USB cable
  3. The LED is of, the clap sensor is off
  4. I plug in the clap sensor, the clap sensor boots
  5. If I clap the LED goes on and off

I think the problem is how I did the pull-up for the clap sensor but I don't know what I did wrong.


Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?

Have you got a current limit resistor in series with your LED?

The sensor appears to have an open collector output.
Have you got a pullup resistor on the output pin of the sensor? (10K or 4K7)
Or have you got INPUT_PULLUP in your code for the Arduino input pin it is connected to?

Thanks.. Tom.. :slight_smile:

Hello Tom,

I've had a copy of my circuit in the first post.

I had a pullup resistor on the output pin (10k) but there was probably something wrong. Using the INPUT_PULLUP worked :slight_smile:

I thought it shouldn't make any difference but now it works.

Thank you very much for your help!

You need to place a current limit resistor in series with your LED, at the moment it will be drawing more current from the Micro that it is rated at.

Tom… :slight_smile: