Blog » VFD tube counter v0.2
Posted on 1289161688|%A: %d %B, %Y|agohover
I have a new build of the VFD tube email counter which improves several aspects of the original:
- replaced atmega8 microcontroller with smaller attiny2313
- replaced IRF730 power mosfet with smaller IRFD110
- replaced $20 FTDI USB-serial cable with $2 PL2303 cable
- replaced boring old white breadboard with fancy new transparent breadboard
- replaced ugly breadboard wires with shiny magwire
However, by far the biggest change is the elimination of 7 transistors. The first design used the conventional high-side switch arrangement of a level-shifting NPN to switch a PNP driving each segment anode, but it bothered me that Jon Stanley was able to get his single-tube clock working without the level-shifting NPNs. Now, Jon's clock is operating at a lower voltage than mine, and he's using a PIC instead of an AVR, so I wasn't sure if I could make that work. It seems that compensating for the higher voltage with a bigger base resistor works just fine so far.
If it continues to work well, I'll put it on a circuit board and make a nice aluminum case for it, like this one.