Signal Tracer protection circuits

Discussion in 'General Electronics Chat' started by Arjune, Jun 3, 2018.

  1. Arjune

    Thread Starter Member

    Jan 6, 2018
    I made a signal Tracer for audio circuits and I want to protect the input so I guess I can use back-to-back diodes from input of signal Tracer to ground and a resistor from there to the probe wire to the tested circuit right?
    back to back diodes.png
  2. Hymie

    Active Member

    Mar 30, 2018
    Your proposed circuit will work with any general-purpose diodes (1N4148 or 1N400X).

    Although it will limit the voltage across the resistor connected from the inverting input to ground to +/-0.7V
  3. danadak

    Distinguished Member

    Mar 10, 2018

    Input R value can be tailored to application requirements.

    Note R along with stray C and CMOS input Gate C affects signal fidelity being
    traced, depending on range of freqs you are working with.

    Regards, Dana.
  4. MisterBill2

    Distinguished Member

    Jan 23, 2018
    Depending on what sort of voltages you want to trace, it may also work to include a voltage-divider type of attenuator in front of the protection diode clamping circuit. In addition, a series capacitor with an adequate voltage rating can provide isolation of the DC components of the voltage that you are tracing. And a really simple way to increase the voltage range that will reach your amplifier is to use two or three diodes in series in each side of the diode clamp, instead of just a single diode.
  5. Janis59

    Active Member

    Aug 21, 2017
    Cant see any use of such in the way it shown. I had a tracer what I bought somewhere at Sweden, probably Biltema chain-store for dollar or two. And it turned out be extremely helpful thingy. The rather large frequency (about 100 kHz) AM modulated with audiotone is the thing to hang between gnd and wire to be traced. Then turn-on the receiver and in ost thickest cable bunch it will demand a seconds to find to which schtekker which lamelle this wire is willing to go, and even branching if it have a place. It see even a inner crush of wire, as well as shortcomes. Thus You need a 6xNor element generator and sniffer circuit resonating at frequency of generator.
    Then my boss pushed it into network under the tension. I have repaired it again, however the plastic box now is more brutal, without of proper elegance.
  6. MisterBill2

    Distinguished Member

    Jan 23, 2018
    It appears that Janis59 is describing a wire tracer, AKA a circuit tracer, which is a quite different but VERY USEFUL tool. The signal tracer is for an entirely different application, not at all like wire tracing. The two tool types would not be similar, I don't think. BUT I can see where the confusion would come from.