This tester will give a signal if there is a short circuit in the inductor between the turns, even if it is one turn.The device is assembled on 5 C1815GR transistors.
A transmitter is assembled on the transistor VT1, which emits a signal around the coil L1.This signal is received by the coil L2, and a receiver is assembled on the transistor VT2.There is an electromagnetic connection between the coils L1-L2.If there is a short circuit in the winding being tested, this will disrupt the connection between L1-L2 and the device will signal this with an LED.
Coils L1-L2 have an inductance of 920 uH and 7.4 mH and are wound on a ferrite core.I used ready-made chokes, but the inductance values may be different.If there are chokes with a different inductance, try to apply them, the main thing is that the inductance of L2 is about 7-10 times greater than L1.
Ferrite cores L1-L2 must be in the same plane.
The frequency of the transmitter in my case is about 30kHz
Customization.Adjust the sensitivity of the tester with the tuning resistor R6, at which there will be a reaction to a short-circuited turn, the LEDs should switch clearly.The short-circuited coil should capture two ferrite cores L1-L2
If a short circuit occurs in the winding, the LEDs switch
Here, in the armature of the electric motor, I specially made a short circuit in the winding
Bring the armature to the two ferrite cores in such a way that there is a clear switching of the LEDs where a short circuit occurred on the winding.This way you will see where the short circuit occurred
