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  • telephonic Tone and Probe schematic

    From Bartolomeo Pestalozzi@21:1/5 to All on Fri Sep 15 04:57:06 2023
    Hello,
    I am looking for an electric schematic of a telephonic Tone and Probe.

    Professional instrumet are like this: https://www.fluke.com/en-us/product/network-cable-testers/copper/pro3000f60-kit I don't have the pretension nor the ambition to make a similar project.
    I would like to build a simple object to identify the stremity wires.



    Thank you
    Umberto

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From John Larkin@21:1/5 to bartolomeopestalozzi65@gmail.com on Fri Sep 15 06:01:22 2023
    On Fri, 15 Sep 2023 04:57:06 -0700 (PDT), Bartolomeo Pestalozzi <bartolomeopestalozzi65@gmail.com> wrote:

    Hello,
    I am looking for an electric schematic of a telephonic Tone and Probe.

    Professional instrumet are like this: >https://www.fluke.com/en-us/product/network-cable-testers/copper/pro3000f60-kit
    I don't have the pretension nor the ambition to make a similar project.
    I would like to build a simple object to identify the stremity wires.



    Thank you
    Umberto

    Amazon has wire tracer kits for around $16. I got one and it's
    interesting. You can hear all sorts of e-fields.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Bartolomeo Pestalozzi@21:1/5 to All on Fri Sep 15 06:47:19 2023
    Il giorno venerdì 15 settembre 2023 alle 15:01:44 UTC+2 John Larkin ha scritto:
    On Fri, 15 Sep 2023 04:57:06 -0700 (PDT), Bartolomeo Pestalozzi <bartolomeop...@gmail.com> wrote:

    Hello,
    I am looking for an electric schematic of a telephonic Tone and Probe.

    Professional instrumet are like this: >https://www.fluke.com/en-us/product/network-cable-testers/copper/pro3000f60-kit
    I don't have the pretension nor the ambition to make a similar project.
    I would like to build a simple object to identify the stremity wires.



    Thank you
    Umberto
    Amazon has wire tracer kits for around $16. I got one and it's
    interesting. You can hear all sorts of e-fields.

    My purpose was to design one, anyway thanks for the indication.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Martin Rid@21:1/5 to Bartolomeo Pestalozzi on Fri Sep 15 12:21:22 2023
    Bartolomeo Pestalozzi <bartolomeopestalozzi65@gmail.com> Wrote in
    message:r
    Il giorno venerdì 15 settembre 2023 alle 15:01:44 UTC+2 John Larkin ha scritto:> On Fri, 15 Sep 2023 04:57:06 -0700 (PDT), Bartolomeo Pestalozzi > <bartolomeop...@gmail.com> wrote: > > >Hello, > >I am looking for an electric schematic of a telephonic
    Tone and Probe. > > > >Professional instrumet are like this: > >https://www.fluke.com/en-us/product/network-cable-testers/copper/pro3000f60-kit > >I don't have the pretension nor the ambition to make a similar project. > >I would like to build a simple
    object to identify the stremity wires. > > > > > > > >Thank you > >Umberto> Amazon has wire tracer kits for around $16. I got one and it's > interesting. You can hear all sorts of e-fields.My purpose was to design one, anyway thanks for the indication.

    You can drive a reversed biased diode with a 555 running s a
    frequency in the audio band. This will create a nice broad
    spectrum modulated hash.
    Then use a lm386 audio amp a nd attach the input to a short
    antenna probe as the reciever.
    I used this setup for many years, and it always works.

    Cheers
    Cheers
    --


    ----Android NewsGroup Reader---- https://piaohong.s3-us-west-2.amazonaws.com/usenet/index.html

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From John Larkin@21:1/5 to martin_riddle@verison.net on Fri Sep 15 12:30:07 2023
    On Fri, 15 Sep 2023 12:21:22 -0400 (EDT), Martin Rid <martin_riddle@verison.net> wrote:

    Bartolomeo Pestalozzi <bartolomeopestalozzi65@gmail.com> Wrote in
    message:r
    Il giorno venerdì 15 settembre 2023 alle 15:01:44 UTC+2 John Larkin ha scritto:> On Fri, 15 Sep 2023 04:57:06 -0700 (PDT), Bartolomeo Pestalozzi > <bartolomeop...@gmail.com> wrote: > > >Hello, > >I am looking for an electric schematic of a telephonic
    Tone and Probe. > > > >Professional instrumet are like this: > >https://www.fluke.com/en-us/product/network-cable-testers/copper/pro3000f60-kit > >I don't have the pretension nor the ambition to make a similar project. > >I would like to build a simple
    object to identify the stremity wires. > > > > > > > >Thank you > >Umberto> Amazon has wire tracer kits for around $16. I got one and it's > interesting. You can hear all sorts of e-fields.My purpose was to design one, anyway thanks for the indication.

    You can drive a reversed biased diode with a 555 running s a
    frequency in the audio band. This will create a nice broad
    spectrum modulated hash.
    Then use a lm386 audio amp a nd attach the input to a short
    antenna probe as the reciever.
    I used this setup for many years, and it always works.

    Cheers
    Cheers

    The probe should be very high impedance. Use a jfet or a cmos opamp
    and a lot of resistance to ground.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Martin Rid@21:1/5 to John Larkin on Fri Sep 15 16:03:44 2023
    John Larkin <jjlarkin@highlandtechnology.com> Wrote in message:r
    On Fri, 15 Sep 2023 12:21:22 -0400 (EDT), Martin Rid<martin_riddle@verison.net> wrote:>Bartolomeo Pestalozzi <bartolomeopestalozzi65@gmail.com> Wrote in> message:r>> Il giorno venerdì 15 settembre 2023 alle 15:01:44 UTC+2 John Larkin ha scritto:> On
    Fri, 15 Sep 2023 04:57:06 -0700 (PDT), Bartolomeo Pestalozzi > <bartolomeop...@gmail.com> wrote: > > >Hello, > >I am looking for an electric schematic of a telephonic Tone and Probe. > > > >Professional instrumet are like this: > >https://www.fluke.com/
    en-us/product/network-cable-testers/copper/pro3000f60-kit > >I don't have the pretension nor the ambition to make a similar project. > >I would like to build a simple object to identify the stremity wires. > > > > > > > >Thank you > >Umberto> Amazon has
    wire tracer kits for around $16. I got one and it's > interesting. You can hear all sorts of e-fields.My purpose was to design one, anyway thanks for the indication.>>You can drive a reversed biased diode with a 555 running s a> frequency in the audio
    band. This will create a nice broad> spectrum modulated hash.>Then use a lm386 audio amp a nd attach the input to a short> antenna probe as the reciever.>I used this setup for many years, and it always works.>>Cheers>CheersThe probe should be very high
    impedance. Use a jfet or a cmos opampand a lot of resistance to ground.

    Oh, just a cap to the probe tip. The lm386 has 28db of gain. If
    it squeals when you touch the probe tip you got gain.


    Cheers
    --


    ----Android NewsGroup Reader---- https://piaohong.s3-us-west-2.amazonaws.com/usenet/index.html

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From John Larkin@21:1/5 to martin_riddle@verison.net on Fri Sep 15 13:51:44 2023
    On Fri, 15 Sep 2023 16:03:44 -0400 (EDT), Martin Rid <martin_riddle@verison.net> wrote:

    John Larkin <jjlarkin@highlandtechnology.com> Wrote in message:r
    On Fri, 15 Sep 2023 12:21:22 -0400 (EDT), Martin Rid<martin_riddle@verison.net> wrote:>Bartolomeo Pestalozzi <bartolomeopestalozzi65@gmail.com> Wrote in> message:r>> Il giorno venerdì 15 settembre 2023 alle 15:01:44 UTC+2 John Larkin ha scritto:> On
    Fri, 15 Sep 2023 04:57:06 -0700 (PDT), Bartolomeo Pestalozzi > <bartolomeop...@gmail.com> wrote: > > >Hello, > >I am looking for an electric schematic of a telephonic Tone and Probe. > > > >Professional instrumet are like this: > >https://www.fluke.com/
    en-us/product/network-cable-testers/copper/pro3000f60-kit > >I don't have the pretension nor the ambition to make a similar project. > >I would like to build a simple object to identify the stremity wires. > > > > > > > >Thank you > >Umberto> Amazon has
    wire tracer kits for around $16. I got one and it's > interesting. You can hear all sorts of e-fields.My purpose was to design one, anyway thanks for the indication.>>You can drive a reversed biased diode with a 555 running s a> frequency
    in the audio band. This will create a nice broad> spectrum modulated hash.>Then use a lm386 audio amp a nd attach the input to a short> antenna probe as the reciever.>I used this setup for many years, and it always works.>>Cheers>CheersThe probe should
    be very high impedance. Use a jfet or a cmos opampand a lot of resistance to ground.

    Oh, just a cap to the probe tip. The lm386 has 28db of gain. If
    it squeals when you touch the probe tip you got gain.


    Cheers

    Yikes. LM386 is an ancient bipolar part with < 50K input impedance.
    Given, say, a 5 pF antenna/probe, the highpass corner frequency is
    about 300 KHz.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Fred Bloggs@21:1/5 to John Larkin on Fri Sep 15 15:51:17 2023
    On Friday, September 15, 2023 at 3:30:34 PM UTC-4, John Larkin wrote:
    On Fri, 15 Sep 2023 12:21:22 -0400 (EDT), Martin Rid
    <martin...@verison.net> wrote:

    Bartolomeo Pestalozzi <bartolomeop...@gmail.com> Wrote in
    message:r
    Il giorno venerdÄ› 15 settembre 2023 alle 15:01:44 UTC+2 John Larkin ha scritto:> On Fri, 15 Sep 2023 04:57:06 -0700 (PDT), Bartolomeo Pestalozzi > <bartolomeop...@gmail.com> wrote: > > >Hello, > >I am looking for an electric schematic of a
    telephonic Tone and Probe. > > > >Professional instrumet are like this: > >https://www.fluke.com/en-us/product/network-cable-testers/copper/pro3000f60-kit > >I don't have the pretension nor the ambition to make a similar project. > >I would like to build
    a simple object to identify the stremity wires. > > > > > > > >Thank you > >Umberto> Amazon has wire tracer kits for around $16. I got one and it's > interesting. You can hear all sorts of e-fields.My purpose was to design one, anyway thanks for the
    indication.

    You can drive a reversed biased diode with a 555 running s a
    frequency in the audio band. This will create a nice broad
    spectrum modulated hash.
    Then use a lm386 audio amp a nd attach the input to a short
    antenna probe as the reciever.
    I used this setup for many years, and it always works.

    Cheers
    Cheers
    The probe should be very high impedance. Use a jfet or a cmos opamp
    and a lot of resistance to ground.

    Almost forgot. Brief 300 page treatise on calculating capacitance to the nth degree:

    https://apps.dtic.mil/sti/tr/pdf/AD0727198.pdf

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Fred Bloggs@21:1/5 to John Larkin on Fri Sep 15 15:48:20 2023
    On Friday, September 15, 2023 at 3:30:34 PM UTC-4, John Larkin wrote:
    On Fri, 15 Sep 2023 12:21:22 -0400 (EDT), Martin Rid
    <martin...@verison.net> wrote:

    Bartolomeo Pestalozzi <bartolomeop...@gmail.com> Wrote in
    message:r
    Il giorno venerdÄ› 15 settembre 2023 alle 15:01:44 UTC+2 John Larkin ha scritto:> On Fri, 15 Sep 2023 04:57:06 -0700 (PDT), Bartolomeo Pestalozzi > <bartolomeop...@gmail.com> wrote: > > >Hello, > >I am looking for an electric schematic of a
    telephonic Tone and Probe. > > > >Professional instrumet are like this: > >https://www.fluke.com/en-us/product/network-cable-testers/copper/pro3000f60-kit > >I don't have the pretension nor the ambition to make a similar project. > >I would like to build
    a simple object to identify the stremity wires. > > > > > > > >Thank you > >Umberto> Amazon has wire tracer kits for around $16. I got one and it's > interesting. You can hear all sorts of e-fields.My purpose was to design one, anyway thanks for the
    indication.

    You can drive a reversed biased diode with a 555 running s a
    frequency in the audio band. This will create a nice broad
    spectrum modulated hash.
    Then use a lm386 audio amp a nd attach the input to a short
    antenna probe as the reciever.
    I used this setup for many years, and it always works.

    Cheers
    Cheers
    The probe should be very high impedance. Use a jfet or a cmos opamp
    and a lot of resistance to ground.

    It's obviously a directional E-field probe working strictly with coupling capacitance. The probe tip, pickup, is oriented perpendicularly to infinite line of charge and connects to a circuit in an insulated probe case. The capacitance between the circuit
    common, of what has to be a high impedance transconductance preamp, and the user's body and back to the infinite line cable completes the circuit. The probe tip geometry must be the best they could do cheaply to create the greatest sensitivity of probe
    orientation relative to the cable. My guess is they're working with a charge amplifier. And there's something up with probe tip geometry that creates a very rapid rolloff for frequencies below 1kHz.

    Note they state this works on lines up to 10 miles length. The cheap amazon stuff is stretching it to make 1000 ft, and the positional discrimination between cables probably isn't very good.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jan Panteltje@21:1/5 to jjlarkin@highlandtechnology.com on Sat Sep 16 05:22:45 2023
    On a sunny day (Fri, 15 Sep 2023 13:51:44 -0700) it happened John Larkin <jjlarkin@highlandtechnology.com> wrote in <7ig9gi5lvb8ho1p4onrtbed451a1ftrmfn@4ax.com>:

    On Fri, 15 Sep 2023 16:03:44 -0400 (EDT), Martin Rid ><martin_riddle@verison.net> wrote:

    John Larkin <jjlarkin@highlandtechnology.com> Wrote in message:r
    On Fri, 15 Sep 2023 12:21:22 -0400 (EDT), Martin Rid<martin_riddle@verison.net> wrote:>Bartolomeo Pestalozzi
    <bartolomeopestalozzi65@gmail.com> Wrote in> message:r>> Il giorno venerdì 15 settembre 2023 alle 15:01:44 UTC+2 John Larkin ha scritto:> On
    Fri, 15 Sep 2023 04:57:06 -0700 (PDT), Bartolomeo Pestalozzi > <bartolomeop...@gmail.com> wrote: > > >Hello, > >I am looking for an
    electric schematic of a telephonic Tone and Probe. > > > >Professional instrumet are like this: >
    https://www.fluke.com/en-us/product/network-cable-testers/copper/pro3000f60-kit > >I don't have the pretension nor the ambition to make a similar project. >
    I would like to build a simple object to identify the stremity wires. > > > > > > > >Thank you > >Umberto> Amazon has wire
    tracer kits for around $16. I got one and it's > interesting. You can hear all sorts of e-fields.My purpose was to design one,
    anyway thanks for the indication.>>You can drive a reversed biased diode with a 555 running s a> frequency
    in the audio band. This will create a nice broad> spectrum modulated hash.>Then use a lm386 audio amp a nd attach the input to
    a short> antenna probe as the reciever.>I used this setup for many years, and it always works.>>Cheers>CheersThe probe should be
    very high impedance. Use a jfet or a cmos opampand a lot of resistance to ground.

    Oh, just a cap to the probe tip. The lm386 has 28db of gain. If
    it squeals when you touch the probe tip you got gain.


    Cheers

    Yikes. LM386 is an ancient bipolar part with < 50K input impedance.
    Given, say, a 5 pF antenna/probe, the highpass corner frequency is
    about 300 KHz.


    I still have some, chip is OK, and still available I think.
    https://hackerstore.nl/Artikel/310
    say 4 USD for the complete amp, inlcuding volume knob!

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From John Larkin@21:1/5 to All on Sat Sep 16 04:52:06 2023
    On Sat, 16 Sep 2023 05:22:45 GMT, Jan Panteltje <alien@comet.invalid>
    wrote:

    On a sunny day (Fri, 15 Sep 2023 13:51:44 -0700) it happened John Larkin ><jjlarkin@highlandtechnology.com> wrote in ><7ig9gi5lvb8ho1p4onrtbed451a1ftrmfn@4ax.com>:

    On Fri, 15 Sep 2023 16:03:44 -0400 (EDT), Martin Rid >><martin_riddle@verison.net> wrote:

    John Larkin <jjlarkin@highlandtechnology.com> Wrote in message:r
    On Fri, 15 Sep 2023 12:21:22 -0400 (EDT), Martin Rid<martin_riddle@verison.net> wrote:>Bartolomeo Pestalozzi
    <bartolomeopestalozzi65@gmail.com> Wrote in> message:r>> Il giorno venerdì 15 settembre 2023 alle 15:01:44 UTC+2 John Larkin ha scritto:> On
    Fri, 15 Sep 2023 04:57:06 -0700 (PDT), Bartolomeo Pestalozzi > <bartolomeop...@gmail.com> wrote: > > >Hello, > >I am looking for an
    electric schematic of a telephonic Tone and Probe. > > > >Professional instrumet are like this: >
    https://www.fluke.com/en-us/product/network-cable-testers/copper/pro3000f60-kit > >I don't have the pretension nor the ambition to make a similar project. >
    I would like to build a simple object to identify the stremity wires. > > > > > > > >Thank you > >Umberto> Amazon has wire
    tracer kits for around $16. I got one and it's > interesting. You can hear all sorts of e-fields.My purpose was to design one,
    anyway thanks for the indication.>>You can drive a reversed biased diode with a 555 running s a> frequency
    in the audio band. This will create a nice broad> spectrum modulated hash.>Then use a lm386 audio amp a nd attach the input to
    a short> antenna probe as the reciever.>I used this setup for many years, and it always works.>>Cheers>CheersThe probe should be
    very high impedance. Use a jfet or a cmos opampand a lot of resistance to ground.

    Oh, just a cap to the probe tip. The lm386 has 28db of gain. If
    it squeals when you touch the probe tip you got gain.


    Cheers

    Yikes. LM386 is an ancient bipolar part with < 50K input impedance.
    Given, say, a 5 pF antenna/probe, the highpass corner frequency is
    about 300 KHz.


    I still have some, chip is OK, and still available I think.
    https://hackerstore.nl/Artikel/310
    say 4 USD for the complete amp, inlcuding volume knob!

    The 10K pot makes the input impeance even lower, even worse as an
    e-field probe.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jan Panteltje@21:1/5 to jjlarkin@highlandtechnology.com on Sat Sep 16 12:52:55 2023
    On a sunny day (Sat, 16 Sep 2023 04:52:06 -0700) it happened John Larkin <jjlarkin@highlandtechnology.com> wrote in <rj5bgitnmcvc1n3iu1nfgtufko7djs77rb@4ax.com>:

    On Sat, 16 Sep 2023 05:22:45 GMT, Jan Panteltje <alien@comet.invalid>
    wrote:

    On a sunny day (Fri, 15 Sep 2023 13:51:44 -0700) it happened John Larkin >><jjlarkin@highlandtechnology.com> wrote in >><7ig9gi5lvb8ho1p4onrtbed451a1ftrmfn@4ax.com>:

    On Fri, 15 Sep 2023 16:03:44 -0400 (EDT), Martin Rid >>><martin_riddle@verison.net> wrote:

    John Larkin <jjlarkin@highlandtechnology.com> Wrote in message:r
    On Fri, 15 Sep 2023 12:21:22 -0400 (EDT), Martin Rid<martin_riddle@verison.net> wrote:>Bartolomeo Pestalozzi
    <bartolomeopestalozzi65@gmail.com> Wrote in> message:r>> Il giorno venerdì 15 settembre 2023 alle 15:01:44 UTC+2 John
    Larkin ha scritto:> On
    Fri, 15 Sep 2023 04:57:06 -0700 (PDT), Bartolomeo Pestalozzi > <bartolomeop...@gmail.com> wrote: > > >Hello, > >I am
    looking for an
    electric schematic of a telephonic Tone and Probe. > > > >Professional instrumet are like this: >
    https://www.fluke.com/en-us/product/network-cable-testers/copper/pro3000f60-kit > >I don't have the pretension nor the
    ambition to make a similar project. >
    I would like to build a simple object to identify the stremity wires. > > > > > > > >Thank you > >Umberto> Amazon has
    wire
    tracer kits for around $16. I got one and it's > interesting. You can hear all sorts of e-fields.My purpose was to design
    one,
    anyway thanks for the indication.>>You can drive a reversed biased diode with a 555 running s a> frequency
    in the audio band. This will create a nice broad> spectrum modulated hash.>Then use a lm386 audio amp a nd attach the input
    to
    a short> antenna probe as the reciever.>I used this setup for many years, and it always works.>>Cheers>CheersThe probe should
    be
    very high impedance. Use a jfet or a cmos opampand a lot of resistance to ground.

    Oh, just a cap to the probe tip. The lm386 has 28db of gain. If
    it squeals when you touch the probe tip you got gain.


    Cheers

    Yikes. LM386 is an ancient bipolar part with < 50K input impedance. >>>Given, say, a 5 pF antenna/probe, the highpass corner frequency is
    about 300 KHz.


    I still have some, chip is OK, and still available I think.
    https://hackerstore.nl/Artikel/310
    say 4 USD for the complete amp, inlcuding volume knob!

    The 10K pot makes the input impeance even lower, even worse as an
    e-field probe.

    You could always add a JFET or MOSFET, few more cents.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Fred Bloggs@21:1/5 to John Larkin on Sat Sep 16 07:24:12 2023
    On Friday, September 15, 2023 at 3:30:34 PM UTC-4, John Larkin wrote:
    On Fri, 15 Sep 2023 12:21:22 -0400 (EDT), Martin Rid
    <martin...@verison.net> wrote:

    Bartolomeo Pestalozzi <bartolomeop...@gmail.com> Wrote in
    message:r
    Il giorno venerdÄ› 15 settembre 2023 alle 15:01:44 UTC+2 John Larkin ha scritto:> On Fri, 15 Sep 2023 04:57:06 -0700 (PDT), Bartolomeo Pestalozzi > <bartolomeop...@gmail.com> wrote: > > >Hello, > >I am looking for an electric schematic of a
    telephonic Tone and Probe. > > > >Professional instrumet are like this: > >https://www.fluke.com/en-us/product/network-cable-testers/copper/pro3000f60-kit > >I don't have the pretension nor the ambition to make a similar project. > >I would like to build
    a simple object to identify the stremity wires. > > > > > > > >Thank you > >Umberto> Amazon has wire tracer kits for around $16. I got one and it's > interesting. You can hear all sorts of e-fields.My purpose was to design one, anyway thanks for the
    indication.

    You can drive a reversed biased diode with a 555 running s a
    frequency in the audio band. This will create a nice broad
    spectrum modulated hash.
    Then use a lm386 audio amp a nd attach the input to a short
    antenna probe as the reciever.
    I used this setup for many years, and it always works.

    Cheers
    Cheers
    The probe should be very high impedance. Use a jfet or a cmos opamp
    and a lot of resistance to ground.

    I'm starting to lean toward a piezo effect probe. E-field sensors based on a electric field dependent dielectric sandwiched between piezo ceramic plates have been in development for years. Also the piezo is a good way to get very high Q bandpass. It's
    ultra high-Z all the way. A probe made of this material does have a susceptibility to microphonics- converting vibration to electric.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From John Larkin@21:1/5 to All on Sat Sep 16 08:31:58 2023
    On Sat, 16 Sep 2023 12:52:55 GMT, Jan Panteltje <alien@comet.invalid>
    wrote:

    On a sunny day (Sat, 16 Sep 2023 04:52:06 -0700) it happened John Larkin ><jjlarkin@highlandtechnology.com> wrote in ><rj5bgitnmcvc1n3iu1nfgtufko7djs77rb@4ax.com>:

    On Sat, 16 Sep 2023 05:22:45 GMT, Jan Panteltje <alien@comet.invalid> >>wrote:

    On a sunny day (Fri, 15 Sep 2023 13:51:44 -0700) it happened John Larkin >>><jjlarkin@highlandtechnology.com> wrote in >>><7ig9gi5lvb8ho1p4onrtbed451a1ftrmfn@4ax.com>:

    On Fri, 15 Sep 2023 16:03:44 -0400 (EDT), Martin Rid >>>><martin_riddle@verison.net> wrote:

    John Larkin <jjlarkin@highlandtechnology.com> Wrote in message:r
    On Fri, 15 Sep 2023 12:21:22 -0400 (EDT), Martin Rid<martin_riddle@verison.net> wrote:>Bartolomeo Pestalozzi
    <bartolomeopestalozzi65@gmail.com> Wrote in> message:r>> Il giorno venerdì 15 settembre 2023 alle 15:01:44 UTC+2 John
    Larkin ha scritto:> On
    Fri, 15 Sep 2023 04:57:06 -0700 (PDT), Bartolomeo Pestalozzi > <bartolomeop...@gmail.com> wrote: > > >Hello, > >I am
    looking for an
    electric schematic of a telephonic Tone and Probe. > > > >Professional instrumet are like this: >
    https://www.fluke.com/en-us/product/network-cable-testers/copper/pro3000f60-kit > >I don't have the pretension nor the
    ambition to make a similar project. >
    I would like to build a simple object to identify the stremity wires. > > > > > > > >Thank you > >Umberto> Amazon has
    wire
    tracer kits for around $16. I got one and it's > interesting. You can hear all sorts of e-fields.My purpose was to design
    one,
    anyway thanks for the indication.>>You can drive a reversed biased diode with a 555 running s a> frequency
    in the audio band. This will create a nice broad> spectrum modulated hash.>Then use a lm386 audio amp a nd attach the input
    to
    a short> antenna probe as the reciever.>I used this setup for many years, and it always works.>>Cheers>CheersThe probe should
    be
    very high impedance. Use a jfet or a cmos opampand a lot of resistance to ground.

    Oh, just a cap to the probe tip. The lm386 has 28db of gain. If
    it squeals when you touch the probe tip you got gain.


    Cheers

    Yikes. LM386 is an ancient bipolar part with < 50K input impedance. >>>>Given, say, a 5 pF antenna/probe, the highpass corner frequency is >>>>about 300 KHz.


    I still have some, chip is OK, and still available I think.
    https://hackerstore.nl/Artikel/310
    say 4 USD for the complete amp, inlcuding volume knob!

    The 10K pot makes the input impeance even lower, even worse as an
    e-field probe.

    You could always add a JFET or MOSFET, few more cents.

    Yes, a jfet or a cmos opamp

    You can make a self-biasing jfet amp with just the jfet and a source
    resistor to ground. I did that for NASA. It involved rocket tests and alligators.

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