Re: [neonixie-l] Push-pull driving cathodes

Yep. A lot of designs just use individual HV transistors for each cathode. I recommend mpsa42 personally as they are ideal for cathode driving and not expensive. They come in several different packages including sot23 SMD if you need small.. David On Sat, 9 Mar 2019, 15:31 Jasper C., wrote:

Re: [neonixie-l] Push-pull driving cathodes

> > I was planning to not multiplex my nixies, probably leaving all cathodes > connected directly to the HV line, and placing current liming resistors on > the cathodes. Was interested to see if I'd need to tweak any of the > individual resistor values uniform current/brightness. > I only jus

Re: [neonixie-l] Push-pull driving cathodes

Jasper, I didn't use any fancy switching power supply knowledge - in fact, I copied the switching power supply schematic straight out of the LT1308 data sheet! The clever part was figuring out that I could do things with the feedback resistor network to achieve current regulation and blanking vol

Re: [neonixie-l] Push-pull driving cathodes

Another important fact about Nixie tube cathodes: turning on one cathode by pulling it to zero volts causes it to steer all the available current away from the other cathodes, causing them to be dark. This is why you only need a 50V switch on each cathode. The caveat is that if no cathodes are pull

Re: [neonixie-l] Push-pull driving cathodes

The required voltage rating of a cathode driver has been debated in this forum a few times. There are 2 opinions that I know of - The driver needs to be rated at the full anode-supply voltage - The driver only needs to be rated at (Anode_supply_voltage - Voltage_drop_across_nixie_tube)

Re: [neonixie-l] Push-pull driving cathodes

On Monday, 4 March 2019 04:12:55 UTC+8, nixiebunny wrote: > > The voltage applied to the elements of a Nixie tube is not as > straightforward as you may think. Keep in mind that there is a voltage drop > from anode to an 'on' cathode of ~130-140 volts, due to the ionized gas. > Also, the capac

Re: [neonixie-l] Push-pull driving cathodes

So I was originally looking at the Microchip HV513 . It's a 250V totem pole driver with 5V input logic and a latch. Was going to do a quick sketch of what I had in mind for the output, but haven't had the time to get round to it. I was planning

Re: [neonixie-l] Push-pull driving cathodes

On Sunday, 3 March 2019 20:53:04 UTC+8, David Pye wrote: > Yes, that's it. If the other segments are high, they just work as more > anodes. > > The best thing imho is just to leave them floating, but they will then > float up to the anode voltage. So provided you have drive circuitry that >

Re: [neonixie-l] Push-pull driving cathodes

I am currently working on a set of multi-digit panaplex displays. One is a 16 digit, 16 segment alphanumeric display and the other is 6 digits and 7 segments. Both were originally intended to be multiplexed across all the digits. There is a 'keep alive’ cathode and an 80v mid rail to keep the di

Re: [neonixie-l] Push-pull driving cathodes

The voltage applied to the elements of a Nixie tube is not as straightforward as you may think. Keep in mind that there is a voltage drop from anode to an 'on' cathode of ~130-140 volts, due to the ionized gas. Also, the capacitance of the tube elements and wiring has an effect on the switching beh

Re: [neonixie-l] Push-pull driving cathodes

For direct-drive, you can just let the cathodes float, and they will be completely dark unless your driver has leakage. I've done 5 full designs with direct-drive that floats the cathode, and none has any issues. All told, there are 52 nixie devices in operation with no hint of failure or leaka

Re: [neonixie-l] Push-pull driving cathodes

Yes, that's it. If the other segments are high, they just work as more anodes. The best thing imho is just to leave them floating, but they will then float up to the anode voltage. So provided you have drive circuitry that can switch the full anode voltage, that is ok. If your drive circuitry ca