cable tester modification

[freddy_uk]

hi,

i have just gone out and got a cable tester from maplins, works like an inductive amplifier, detecting a tone present in the cable. Im detecting tones from 500hz to 3000hz.

I want to take to audio speaker output of this tester and put it through some kind of filter, when a tone between 500hz and 3000hz is detected i want to light an led, the unit is powered by a pp3 battery.

Any suggestions

thanks
freddy

 

[RadioRon]

I don't understand what you want to do. But first, can you post the model of the tester so that we can look up what its specs are?

 

[Mikebits]

I am thinking he wants to use a visual indicator instead of a tone. Maybe a simple comparator circuit would do the trick. Not sure why you would need a filter. If tone is present between 500Hz to 3KHz a comparator would detect that. Are there other frequencies present which you wish to filter out?

 

[kchriste]

Sounds like the device is a cable tracer and not a tester. I don't know why you'd want a visual indication because the loudness of the warble tells you how close you are to the cable.

 

[freddy_uk]

I am thinking he wants to use a visual indicator instead of a tone. Maybe a simple comparator circuit would do the trick. Not sure why you would need a filter. If tone is present between 500Hz to 3KHz a comparator would detect that. Are there other frequencies present which you wish to filter out?

your spot on there... 'probe' already has a speaker and led, when i put it against the audio cable im 'testing' i can hear the tones very faintly at 500hz it becomes clear at 1000hz, at 3000hz its purfect

anyway, i need to provide an output suitable for a device with 1.5v - 4.5v nominal voltage range and current 175mA, its a little motor. i had said led because i didn't want to complicate it too much but with the current being 175 mA i though i should provide this additional info.

ideally i was going remove the exsiting speaker and use audio output from the probe on this additional circuit. The output would only be activated if a tone between 500hz and 3000hz was detected, hence filtering out anything below 500hz or above 3000hz, would also help get rid of any ac hiss and crackle!!

thanks for your replys