This is my first attempt at directly driving nixie tubes without having to multiplex any shift registers and use discrete transistors for each digit (I've done this before and though it was a satisfying project, it was waaay too much soldering!)
>From my understanding, people have been using HV5812 chips to directly drive nixie tubes by using them as sinks for the tubes -- tube anode is connected to HV power supply, and the digit cathodes attached to the 5812's pins; when the 5812 pin is switched on, it outputs up to 70 volts, which decreases the voltage across the nixie digit by 70 volts, taking it below the striking voltage, and when the pin is off, the nixie digit has the full HV potential across it. Since most nixies only pull a few mA per digit, this is within the 5812's spec and can safely be sunk by the chip. Is this correct? I have my power supply set to output 165 VDC, and a resistor divider attached to that which outputs about 66 V for the VPP supply to the 5812. With this setup, if I connect the positive probe from my multimeter to the 165V power supply output and probe the HV output pins of the 5812 with the negative probe, I should see ~99V when the 5812 pin is high, and 165V when the pin is low, correct? After throwing together some PIC code to set one of the HV5812 pins low and the rest high to test this, I'm getting some erratic behavior. On pins that are set high, I get anywhere from 135V to 95V while the low pin is consistently at the expected 165V. While the power supply's output stays at a steady 165V, the voltage at the 5812's VPP pin fluctuates from the expected 66V down into the 30s for some reason. Does anyone have any ideas why this is happening? -- 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.
