UPDATE: A Facebook friend of mine found the same tool on eBay for $25.49.
Jon Cusack — the pedal builder, not the actor — recently turned me on to one of the best DIY tools I’ve ever owned: The Multi-Function Tester TC1.
Jon’s Michigan shop manufactures the pedals I design. He and I were trying to pinpoint the optimal gain for the germanium transistors in two of the new pedals I’m about to release.
I’d been using a multimeter to test gain, which is measured in terms of hFE. An old germanium transistor might have hFE of 50 or less, while a hot silicon Darlington transistor such as an MPSA13 might check in at hFE = 5,000. As you can imagine, it’s a crucial measurement for any stompbox that employs transistors.
But like many before me, I encountered two big problems. First, most multimeters don’t have an hFE function. (To make such measurements, the device needs a trio of sockets so you can plug in the transistor’s three legs.) It’s not a matter of cost. In fact, most high-end multimeters, such as the Fluke models whose prices start at well over $100, omit the function. (To be fair, we’re talking about antique transistor technology, which is pretty much extinct in most modern electronics.) You’re likelier to find an hFE tool on cheaper, more obscure models. So I’d been using bunch of cheap-ass Chinese multimeters just to measure hFE.
But there’s another problem: Those multimeter hFE testers are notorious for their inaccuracy. They’re especially prone to overstating the actual gain. They’re not quite useless, but they’re close.
Jon recommended the TC1 ($41.50), which apparently is only available via eBay in the US. And it’s more useful than I could have imagined.
First off, it gives accurate hFE readings within a hundredth of an hFE unit. It works with silicon and germanium BJTs, FETS, JFETS, and MOSFETS. And dig this: It doesn’t matter which way you orient the pins — it knows which leg is which, so no more jumping online to verify the pinout of a particular part.
Check out the photo: The LCD image tells me that the pin in socket 3 is the collector. Had I inserted it the transistor the other way around, the collector would be marked with a 1. Better still, it also works with resistors, capacitors, and diodes. You don’t even have to switch metering functions, as on a multimeter. Just pop in the part, secure it with the clamp, and TC1 does the rest.
Trust me — if you work with transistors, resistors, caps, and diodes, you want this tool. Now I seldom use my crappy multimeter unless I need its continuity (“beeper”) tool.
Thanks for the excellent tip, Jon! 🙂