> Hi mike, you might have considered this and rejected it, but how about > doing your first clock with numitrons? They don't require the elevated > voltage and small ones can be bought off ebay cheaply.
Another idea is to go ahead and use a 74141 type drivers with an ordinary five volt supply and ten LEDs with a 1k anode resistoror or even small incandescent lamps (you can chop up a holiday light string to get cheap bulbs and sockets). This could be done cheaply or even free. A dead ethernet hub will generally get you a five volt supply and several LEDs. You can get a 74141 chip for a buck or so. You can start lighting LEDs even before you round up a driver chip. Once you have that, you and your kids can manually tie the various input pins to the positive supply or ground, and see how the chip works to drive a single output at a time. You could proceed forward in two ways. You could add a microprocessor and work out how to program the micro and light up the LEDs or bulbs. Or you could try to scrounge up a high voltage supply and some small neon bulbs. Supply the neons with your HV supply, and change the anode resistor to 470k or so, and your 74141 will light them instead of the LEDs. Then, when you find a nixie tube, you can just swap it for the neon bulbs, and change the anode resistor appropriately, still using the same 74141 chip to drive it. This way, you have something up and running soon and cheaply (I find this the best encouragement), you start with safe low voltage, and you can learn about microprocessors a step at a time. If you add a second 74141 or a pair of anode drivers, you get a two-digit display, which is sufficient for getting started with a thermometer. You can quickly learn to read a column of ten lights (LEDs or neons), or you can arrange for them to shine through digit cutouts. This is exactly how the display worked in some HP frequency counters: http://www.hpmemory.org/wa_pages/wall_a_page_11.htm As you can see, I'm a big fan of getting something working at an early stage, doing things on the cheap, and electronics in general. - John KG4L -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To post to this group, send an email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
