Uploaded January 2018 | Updated September 2026, 2 hours ago
This is a very simple Laser Beam Interruption Counter. You can count something or count passing people with this.
This is a very simple Laser Beam Interruption Counter. You can count something or count passing people with this.









![12V car bulb connect to 220V directly
This is series capacitor current limit circuit. Widely used in transformerless power supply.
However, it is dangerous because of the high potential difference with the ground.
In this kind of circuit, may damage the bulb by over current flows due to harmonics. (Current : 2 × π × f × C × V [A] ) 12V car bulb connect to 220V directly](https://i.ytimg.com/vi/4HI3JEzjyu8/mqdefault.jpg)
