A small review of this Micronta Transistorized Signal Trace, which I found at a Verviers flea market in 2026.
I wasn’t hoping it to be a Germanium Signal Tracer, but it is 🙂
The device looked rather grimy with a sticker announcing a “9V ACCU” and a weird hand drawn symbol on the left. Later I realized that was a representation of a 2.5mm headphone jack and the charging polarity:
Closeups of the dents and grime:
Once inside, the device looked beautiful – except, there was no rechargeable battery as such, but a normal 9V alkaline which started corroded. Surprisingly, the battery had 2016 year marked on it, was this used 10 years ago ?
Looking closer at the clumps of wires (and after checking other photos online), it seems the charging part was not part of the original design, but something one of the owners decided to do aftermarket.
The hole was drilled too close to one of the screw posts and the previous owner had to melt more plastic to fit the jack:
I chose not to keep the mod and 3D printed a small cap to cover the hole:
A closer look at the components: 3 x 2SB187 and 1 x 2SB186 Germanium transistors which form the audio amplifier part of a radio. There’s a Ge diode (unmarked) serving as a detector diode for when the device is used in AM RF tracing mode:
I replaced the corroded battery connector, removed the charging part and flushed the potentiometer with some contact cleaner as it was a bit scratchy:
To test it, Tiny SA Ultra is perfect – using with short SMA to Crocodile clips cable which should be fine for the frequencies being tested:
Please set your volume to LOW before unmuting the video:
In conclusion, it works and seems it got its fair share of use, if the owner decided mod it with a rechargeable battery ? But I will never know.
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