How to make a wireless test pen that detects broken cables

How to make a wireless test pen that can detect broken cables, this tool is very useful for finding out the position of a broken cable or checking whether the cable carries electric current or not, this tool has no different function from the wireless test pen that detects broken cables on the market, for those who I like electronics and if you don't have a wireless test pen yet, there's no harm in trying to make one using used components.
Component
1. Optocoupler pc817 / ps817
2. Transistor BC547
3. 1k ohm resistor
4. Supply can use a 3.7v or 5v dc
Hopefully this video on how to make a test pen or wireless test pen can inspire and be useful for you. If this video about how to make a test pen that detects broken cables is useful, don't forget to help by pressing the subscribe, like and share buttons. Thank You...!!!