Re: HP 547a Current Tracer probe useful in finding shorted Capacitors ... was ... Most common capacitor spot failure in 7K scopes?


Yes the logic clip is part of the set:

HP545A = Logic Probe
HP546A = Logic Pulser
HP547A = Current Trace Probe
HP548A = Logic Clip

You can find them sometimes as a set on ebay, but usually selling north of $400-600. I think this set sold new back when at around $1000 (or more), the 547A alone was around $400. But on rare occasions the price of a set on ebay will be extremely good. About 1.5 years ago I finally found a set of the 3 probes with the carry case all in very good condition from a seller in Germany for about EUR 160, shipping included. At the same time there was also a logic clip for sale from a US seller at $45 so I got it as well to complete the set. The case actually has a separate pocket just to slip in the clip.

The Logic clip is very versatile, just clip it onto the IC and it will automatically figure out which pin is Vcc and GND and start to operate. Used mine just last night along logic probe and pulser to test a counter design in building process. The pulser is a work of art, with all the choices of different pulse stream rates that can be selected just by a single push button.

More recently about a year ago there was again on ebay a set of the 3 probes with the case for a mere $100 Buy It Now. I was about to get it as well but then tough to leave it for someone else. The set was gone in the next 10 minutes. And just a few weeks ago there was another set that was sold for $135 BIN. This time I saw the listing on the results page as still available and decided to go after it, but when I went to the actual listing it was already listed as sold. Then just to confirm went back to the results page and it was still there, so I guess the ebay database was just taking its time to update.

BTW the light bulbs used in both the logic and current probe (5V 60mA "Grain of Wheat") are still available cheaply at Mouser for about a dollar a piece if I remember correctly. I bought 10 just in case for any foreseeable future needs and then some. At the time there where still 180 available in stock. If anyone needs the Mouser PN just let me know. Not that these bulbs are going to burn out any time soon, but I figured that the filament or the bulb might break if the probe is accidentally dropped. But hopefully not with the current sensor side hitting the ground as it would then be toast for good and no more bulb needed.


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