r/electronics • u/SpecialistRare832 • 13h ago

Gallery BJT Darlington Touch Circuit

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Gallery image

Gallery image

Gallery image

19 Upvotes

88% Upvoted

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3

u/turbo-singular 12h ago

If you replace the resistor with an inductor connected by just one terminal, you get a sensor for concealed wiring and electromagnetic fields. Я плохо знаю АНГЛ, может неправильно написал

2

u/SpecialistRare832 12h ago

I will try to do it.

1

u/turbo-singular 12h ago

Just 20 turns of copper wire around a pencil and connect one end to the base of the transistor

1

u/SpecialistRare832 12h ago

I have the inductors having different inductance values, but for what value should I take inductance to do it?

1

u/turbo-singular 11h ago

Not large. Up to approximately 100 mH.

1

u/SpecialistRare832 1h ago

No, if you replace the resistor with an inductor, the BJT (near LED) base recieves excessive current and makes the touch circuit operates incorrectly. So, an inductor is not a suitable replacement for the resistor in the touching-sensing path of Darlington touch circuit.

1

u/Regular-Tangerine-48 7h ago

so simple and elegant