This is a classic circuit, but until now I hadn’t gotten around to building one. Its useful whenever you need a floating supply or if you need a quick way to poke a signal voltage into a circuit. (I suggest it for people building and testing x0xb0x’s)
I installed Arduino IDE 009 since I figured I should learn this stuff if I’m going to sell Arduino’s (and clones)
My project today was to build a simple NPN Hfe (Beta) meter to do some tests on the now ultra-rare 2sc2291 matched pairs. My multimeter has one but I wanted to make sure I was testing with the same setup as the one in the datasheet, with a Vce of about 6V and Ic = 1mA. The results are in the x0xd0x wiki
This is the breadboard circuit I used:
its similar to the one described on the x0xb0x page, but with the op amp swapped around for NPN’s
The sketch is rather small, I just take the two analog measurements, do a bit of math and spit out the calculated beta. I checked this against my meter and it matched up for lower betas (although not for higher ones, which may mean I’ve got current leaking into the opamp)
A teaser from Misusage (who made the awesome TileToys a few years ago)…a cute circuit idea to automate knob tweaking! Microcontroller + digital pot + glue = MemPot, a speed-adjustable programmable ‘memory’ potentiometer. Seen here manipulating a modded x0xb0x, yum!
I really need to keep closer tabs on what x0xb0x is doing on the internet. First it torrented some DiVXs from The Pirate Bay. Then it starting trolling craigslist and buying stuff on Amazon with my credit card. Now I find out x0xb0x even has a myspace page!
I blame m0me rath because hes got 4 of them and they probably needed a place to hang out!
In other news, I’m putting up a track in the x0xb0x ‘podcast’ nearly every other day! Check it out for the latest, soon I hope to have it automatically syndicated here.
Its like post-cyber-retro action in here, with the new clear acrylic panels available for the x0xb0x. These are cut and etched using a 35W lasercutter for precision & good looks. New x0x orders can add this, older x0x users can grab a set for $30 from the adafruit webshop.