High,
I want to sense contactless a 5V on/off pulse from a wire at a distance of approximate 5 to 10mm, without going around the wire.
I already tried it with a couple of transistors (picture) but it won't work to sense the 5v pulse.
Is this even possible and how?
Thanks for helping.
a clip on or through hole sensor will not work with dc current especially 5v . without some sort of contact like a meter or logic probe or perhaps a small compass sitting on the wire research a hall effect sensor
Tanks, so it is not possible to detect dc 5v?
Maybe when i increase the voltage to 9V or 12V and use PWM to alternate, and use a coil as sensor?
Captain, sir. Could you be more specific as to what you are trying to detect. First you title you post as trying to detect current on a wire connected to a 5 volt source. Then you ask about detecting a 5 volt pulse. Each can be detected, but not the same way.
Paul
Thanks sir Paul,
I only want to detect connection (yes or no) to a source of choice , so it doesn't matter.
I can put any low voltage signal on it.
CaptainPicar3d:
High,I want to sense contactless a 5V on/off pulse from a wire at a distance of approximate 5 to 10mm, without going around the wire.
I already tried it with a couple of transistors (picture) but it won't work to sense the 5v pulse.
Is this even possible and how?
Thanks for helping.
If you want a sensitive capacitive probe a CMOS logic input pin is way better than something that needs
current like a BJT. However capacitive sensing 10mm away from a wire is very iffy, that's about 0.1pF
of coupling.
For current sensing you'd require a decent amount of current too, and a sensitive hall sensor.
Why not wind a sense wire around the target wire for several inches, giving a more plausible
amount of capacitive coupling.
Is this target wire part of some unit you don't want to alter then?
Do you have access to an oscilloscope so you can see if you are making progress developing a sensor?
Paul
