#706

Episode 706
I build an audio tracer based on the Elenco manual:
www.manualslib...
It has a 1kHz sinewave oscillator and audio amplifier with speaker
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[@jdmccorful]

Nice job. Great feeling when you can say "lets make one" and then do it.

[@Peter-W1]

The only probe I have built was a logic probe around a 40106 CMOS , it had 3 Leds 1, 0 and puls indicator. This was around the 80´s but I still use it sometimes.

[@PapasDino]

The master of re-purposing!

[@frankowalker4662]

Nice and useful. I'd run it off an internal 9V battery and replace the sockets with BNC's so it could be used with normal oscilloscope probes. :)

[@Hellhound604]

Used a signal tracer about 50 years ago, and a logical signal tracer some years later, until I learnt how to properly use an oscilloscope (and could afford one at home). For me they are just a fun tool, combined with a signal injector (did build a Heathkit signal tracer/injector at some stage), but nothing for serious work, but that is just my personal opinion… if I look at other youtube channels just using a DVM for everything, and cant immediately see ripple on voltages, tri-state signals, etc… Ermmmm, an oscilloscope shows you immediately everything you need to know… or maybe it is just the way my brain works???

[@t1d100]

Thank you for the video. Much appreciated. It is right on target for me. I have already built the Elenco version (the circuit that you did not build in this video) and I would like to make an improvement to it... It is well known that these circuits have an annoying habit... When you are testing a DUT's amplifier, you turn the tracer's volume up on the input side of the DUT's amp, because the signal's amplitude is low going into the amp. Then, when you move to the output side of the DUT's amp, you get blasted with a loud volume on the signal tracer. This means that you must ride the volume knob with one hand, while you probe with the other. I did not explain that so well, but I am sure you know of what I speak... So, I want to add a compressor to the signal tracer side (the amplifier) of the circuit. I am studying on compressors, but I do not have enough experience to know what compressor circuit that would be best to use... I have considered W2AEW's attenuating diodes and transistors method. Your photo-optical LED method looks interesting. I would appreciate your suggestion for the type of compressor circuit to use and where to insert it into the Elenco design. Thank you in advance!

[@IMSAIGuy]

I replace the speaker with a resistor and monitor the voltage when I don't want to hear noises.

[@sadunnakipoglu9471]

Thank you and appreciate your effort. Greetings to you from Turkey .

[@IMSAIGuy]

I want to see Göbekli Tepe someday

[@mrbambix]

thank you for this video, loved it!

[@johnnz4375]

Velleman is a Belgian company.

[@gregjones3660]

Thanks Johnny, I’ll swing by Belgium 🇧🇪 and buy a Velleman right away!

[@cowboy6591]

Got to be careful with Cat 5/6 cable high speed networks. You can't send a 1k signal into a powered up router for network without blowing diodes in the router.

[@PhoenixRevealed]

Ok, I gotta admit to almost screaming at the TV at the beginning where you were describing the oscillator as square wave. I love your content and I acknowledge we live in a digital world today, but I'm shocked it wasn't immediately recognized as a classic phase-shift audio oscillator (sometimes called an RC oscillator). www.electronics-tutorials.ws/oscillator/rc_oscillator.html Calling it a square wave oscillator couldn't be further from the truth since this circuit produces the purest sine wave of any simple analog design. The only thing which comes close is the Wein-bridge oscillator, which doesn't need such carefully matched components for a good sine wave and lends itself to adjustable tuning but requires automatic gain control of the oscillator stage (many classic designs used a small light bulb in a feedback loop whose resistance changed as the signal amplitude fluctuates). For best quality signal the phase shift oscillator requires the feedback resistors and capacitors to be precisely matched, which can be difficult, and it's hard to give it effective variable tuning. That said, with the proper components, an RC oscillator will produce simply the purest perfect since wave you can get. Harmonics are effectively nonexistent. R8 has nothing to do with the quality of the sine wave (in fact, I've never seen one there in a traditional RC oscillator). It has a fairly high value and may be used to inject some positive feedback from the emitter into the phase shift network, possibly to reliably start oscillation on power up, although I'm not aware of that being a problem with this type of oscillator. This was one of the first circuits I learned about as a 12-year-old dabbling in electronics half a century ago. Damn, I feel old.

[@johnnytacokleinschmidt515]

Old fashioned signal tracers from 1960's and 1970's specifically built for transistor radios frequently had or had a companion "noise generator" which is a a square wave giving harmonics usable for AF, IF, and RF signal tracing. But you say it's a sine wave and so does his description.

[@brucecollins6435]

Ah but will this work as an RF tracer too? I can imagine it maybe working as a tracer at 455KHz in my old receivers but how high will it work?

[@williamdenbeste9703]

Velleman is a Dutch company.

[@amrkoptan4041]

just great !!

[@rfdave3980]

Oh you didn't check the speaker grasshopper. Should the caps in the phase shift oscillator be mylar? Thank for the video good chuckle.

[@IMSAIGuy]

choice of capacitors is how stable you want the circuit to be. ceramic will be low tolerance and vary with temperature. for this application. ceramic is just fine.

[@8-bitbitsa821]

Ahh hem... it does certainly look like someone has soldered a wire link across the speaker terminals, no ? 🤷🏻‍♂️

[@IMSAIGuy]

no. It was working just fine then suddenly shorted.

[@williamcolvin3609]

Where did you find the little project boxes - they had everything you needed already to use.

[@IMSAIGuy]

estate sale: kzbin.info/www/bejne/hmqnf4dtlJ6ersU

[@ygiannarakis]

Very nice! Could you please share the pcb files for the LM386 amp?

[@IMSAIGuy]

github.com/imsaiguy/LM386-Stereo-Mix

[@ygiannarakis]

@@IMSAIGuy Thank you!

[@surgingcircuits6955]

Going to do a video to show injecting and tracing with it?

[@RC-Heli835]

Good job man! Is there a reason why 1k sine tone is used in signal tracing?

[@IMSAIGuy]

no reason. it is a round number in the center of the human voice spectrum

[@RC-Heli835]

@@IMSAIGuy Thanks! I was wondering if might it be possible to use music audio for signal tracing a radio? I'm fixing to build a nice signal tracer this week end but don't have a tone generator yet. I can probably just use squelch noise for my Stryker 955 radio issue. A barely shorted external speaker has killed 90% of my volume.

[@IMSAIGuy]

@@RC-Heli835 there are audio signal generators apps for cell phones

[@RC-Heli835]

@@IMSAIGuy How would I get it into the radio? 1/8 jack from the phone to a mic cord with some switches for carrier and modulation?

[@RC-Heli835]

@@IMSAIGuy This is the probe I'm building. All its parts are readily available and works with PC speakers. kzbin.info/www/bejne/qF6mc6Ntj5Kad9k I love Mr. Carlsons Super Probe but its got a very elaborate circuit board that would be hard for me to duplicate.

[@minguinsantos5903]

Power suply is 9v?

[@IMSAIGuy]

9 or 12. Doesn't matter