Re: [Amateur-repairs] Test Leads

I have done much the same.  I have made RF probes, capacitor isolated probes, and inductive probes doing this.  Apparently, if you use industrial sewing needles, they aren't as brittle and will last much longer, however, I generally use whatever my wife has available.  The really fine needles are great for SMT probing.

 

73, Clint, VE3CMQ

 

From: Amateur-repairs@groups.io <Amateur-repairs@groups.io> On Behalf Of maxwelloau via groups.io
Sent: Sunday, 12 October 2025 14:20
To: Amateur-repairs@groups.io
Subject: Re: [Amateur-repairs] Test Leads

 

Tip: Make one of these too. I have made these for 40 or closer to 50years! 

 

Get a felt tipped pen, looks like a normal biro (balltel/pentel or similar) normally constructed with a plugin tip area containing a narrow long felt rod, and a plug in top area keeping the large plastic tube containing the felt wet ink reservoir in place. Use it till it runs dry. Keep them in a jar! 

Remove all the felt stuff and throw away. 

Use a sewing machine needle, a jeans needle is usually a bit thicker than some, and super glue or araldite this into the pointy tip holder (knock the ball out, drill whatever), drill a hole in the top plug end, size of a silicon 512 strand cable lead (firm fit best).

Assemble silicon lead through a firm top plug hole (got 2 be careful spelling here) and through the body of the pen. Bare some of the silicon wire to stick out the bottom tip area, solder to the flat of the sewing needle (after the glue/araldite dried solid) and push the tip back into the holder. Keep the cap, most important. 

 

Now you have a VERY sharp tipped probe ideal for dense wires and circuitry. I have even gone into the wire insulation itself to make a measurement (only low voltage cabling) to make measurements not available elsewhere.  

 

Ideal for solder pads, IC legs, square IC's, small tabs, etc. 

 

Goes without saying the more tip protruding from the bottom of the pen tip is more prone to snap off (sewing machine needles are brittle) or short stuff!

Of course put the cap on when not in use and that stops getting jabbed later on! Clip top cap onto the silicon wire when probe is in use. 

 

Of course with the inscrutable friends great manufacturing ability and low cost, they now have 4mm banana socket pointy probes and spare probes available too! 

 

Short answer, a lead for each probe ready to go is better than fiddling about with little plugon dodads any day.  

 

Happy probing.