Wednesday, January 24, 2007


#$!!@#@% Radio Shack

I finally gave up trying to debug the dual darlington chip installation on the Mk 2.1 extruder test board. Instead, I disconnected the offending one, found another piece of landscape on the test board and put in another one.

This time the serial comms weren't affected by the installation. Just as I was checking out the circuit trace by trace my Radio Shack Digital Multimeter decided to give up the ghost. This happened once before. The head guy at the Radio Shack shop that I bought it from pretty much accused me of deliberately buggering it up so that I could get another one. I think that he knew, however, that I'm the sort of okie that will go to corporate headquarters if people don't stand by warrenties, however, so he got me another one and said that if I came in with another broken one he'd see me in hell before he replaced it again.

I just don't know what it can be. I'm working on a circuit board with no voltage higher than 12v and out of the clear blue sky it will decide, always at an inconvenient moment, to just die.

Anyway, this time it decided to wait until the warrenty was past, but I'll tell you, I'm finished buying multimeters from Radio Shack. This is the third one, one $24 one and two $48 dollar ones (one replaced on warrenty with considerable bad grace, mind), that have died on me. It's off to Potters' in the morning, I guess and I'll see if I can get a bullet proof one.

Just think, in a year or so, you'll be able to make your own multimeter. It won't have any cheesy logos or limited warranties. And you certainly won't have to deal with rude sales managers if and when it breaks.
Who says you have to wait a year?

Making a multi-meter is extremely easy. In fact, I think I either saw a 'sample circuit' for either one of the PIC chips, or the Z8 chip for just this application. Both digital and analog are easily within grasp with the set of skills needed to repstrap a reprap. (Unless you happen to require a multimeter to fix your multimeter! lol)
It's easy to make a cheap multimeter. Making a good multimeter sounds a lot harder... A logic probe might be closer to hobby territory.
Got a nice Triplett autoranger. Also got a good discount on it. There's going to be hell to pay if this one dies.
Well my analog RS Micronta is still working after about oh.. 30 years. And I've had to replace the battery a couple times. Can't do without an ohmmeter you know.
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