The length of the glowing portion of these bargraph tubes is fairly proportional to the input current. I personally like the IN-13 better, on two points. (1) Lower full scale current. Only 4mA. The IN-9 is much higher. (2) it has a 3rd electrode, which usually locks the glow to one side. 10 discrete levels is very doable. 12 or 24 can be managed too. The drive circuit is very simple. On the cathode leg, insert an NPN xstr (MPSA42) with a resistor in its emitter leg. Tie the collector to the bargraph cathode. The base to an op-amp output. Connect the op-amp inverting input (-) to the node connecting the resistor to the NPN emitter (other end of the resistor to gnd). Input your signal to the non-inverting input of the op-amp. If the resistor is 680 ohms, 4mA will be achieved with an input voltage of 2.72V (= 680 x 0.004). Divide that by 10, or 272mV per level. You'll need to get a uC with a DAC output, or connect a separate DAC to the uC; either parallel, or serial.
On Monday, May 21, 2012 4:35:54 AM UTC-7, kay486 wrote: > > Hi there, ive been wondering, how precise can you be when you drive those > tubes? Ive been thinking recently that they would make a really nice clock! > Having six or seven tubes next to each other. The thing i need to know is > if its possible with these tubes to have ten precisely given points. That > way you could use them for clock pretty easily. You could even achieve neat > effect if the transitions between every number would be smooth so the glow > would simply grow. > -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To view this discussion on the web, visit https://groups.google.com/d/msg/neonixie-l/-/YI0CcwFUJZ4J. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
