Nixie clock power supplies - Page 1
Forum section: electronics / beginners

author: netdudeuk
author_rank: Frequent Contributor
timestamp: December 30, 2022, 10:31:24 am
content: HiI like to design and build Nixie clocks.I have attached a photo of my latest version of a display PCB along with a prototype controller board.The displays need 180V which I generate using an eBay boost module as can be seen at the right of the photo. I've used several of these with no issues.In order to get a solid 180V I need a 9V supply. I can run with 5V but if it drops even slightly (due to, say, a long USB cable) then I don't get the full 180V and some digits are only partially lit.I also need 5V for all of the logic.So, I can run the whole system with a single 5V supply. However, that's a compromise, as mentioned above.I decided to power the whole project using a regulated 9V wall wart which would then give me a reliable display. Of course, I'd then need to regulate down to 5V as well.I bought a small buck converter module but the output is all over the place so I'm not going to risk blowing the logic components with it. I guess that I could just use a 7805 but then I'd need a heatsink, etc.I'm wondering if I could keep using the 5V only option and just boost to 9V for the eBay boost module using something simple like a transistor or a MOSFET.The boost converter will accept up to 12V. Maybe a capacitor / diode voltage doubler would also be a possibility ?I'm drawing 270mA when using my DP832 to provide 9V to the boost converter.Any ideas please for a simple way out of this quandary ?Thanks

author: Didgitalpunk
author_rank: Contributor
timestamp: December 30, 2022, 01:29:26 pm
content: Heya,voltage doubler will not work, you're not working with AC.The simple solution is to just switch out your dc-dc converter to something that takes a lower input reliably! (and especially whose output doesn't fluctuate with the input)take a look at this one for example:https://www.nixieclock.org/?p=14542.5 to 15 volts in, 170 volts out. tiny as well, and fairly well documented. there's even pinout dimensions so you can design your board so it just plops into your final design as a daughter board.It's a bit expensive, but well worth the money imo. (you can find it on ebay too, just make sure the seller's actually selling the real board ans not a cheap ass copy)If your Nixie board seriously doesn't run on anything lower than 180 volts, you might have a driver problem, not a dc-dc converter problem. check your current limiting resistor(s?) and make sure they're appropriately sized for the tubes you have. Too small and the tube will glow excessively, too big and it might not light up properly/completely/at all. 170 volts is enough to drive IN-12 tubes and even some bigger tubes.Freya

author: MikeK
author_rank: Super Contributor
timestamp: December 30, 2022, 02:44:34 pm
content: FWIW, one of the first YouTube videos from The Signal Path was taking a disposable camera flash circuit and using it to power a Nixie tube.

author: netdudeuk
author_rank: Frequent Contributor
timestamp: December 30, 2022, 03:15:06 pm
content: Quote from: Didgitalpunk on December 30, 2022, 01:29:26 pmThanks for the comprehensive reply.Those dc-dc converters are indeed expensive and I've got several newwww.ebay.co.uk/itm/254794892237ones to use anyway. I'm right at the bottom of their specs at 5V so probably unsurprising that the output voltage isn't guaranteed at below that level.I see these on eBay UK -https://www.ebay.co.uk/itm/353680929903https://www.ebay.co.uk/itm/265114049689Even if I went this way, who's to say that these are genuine versions ?The displays definitely run at a little less than 180V using 1551s with 20K resistors. I'll just see, say, the end of the five faded out. Could I get away with less than 20K for the IN-12s to allow for this ?Thanks again.

author: Didgitalpunk
author_rank: Contributor
timestamp: December 31, 2022, 10:26:10 am
content: QuoteThey certainly look genuine, or at least faithful repros. both come from the same place in china so honestly it could very well be the same warehouse providing the goods... only way to know is either to hope to get a faithful response from the seller(s), or just bite the bullet and hope. I've been burned once on one of these (absolute fake, wrong board design and color, complete with uncleaned flux and half-sideways components!), and ebay gave me a full refund without me having to send the stupid thing back.I'd gladly have given you the link to the seller I used a few years ago for mine, but they don't have the listing anymore :/You could definitely try lower resistor values, E24/E12 should have plenty of adequate values to chose from for this applicationyou could try 18K, that'd give you 10mA instead of 9mA @ 180V, not too much of an increase, or 9.4mA instead of 8.5mA @ 170V.QuoteYou could try and go for USB-PD? first step above 5v is 9v, that'd fit your dc-dc converter just right, you'll just need a 7805 for your uC/driver circuit to give it 5V after that.Freya

author: retiredfeline
author_rank: Frequent Contributor
timestamp: December 31, 2022, 11:13:07 am
content: Quote from: netdudeuk on December 30, 2022, 03:15:06 pmThose are the ones I used for my retro restoration project. They work fine but I use 12V to avoid the spec limit as I do have 12V available. I found out that the instruction that the enable line is also enabled when open is not true. You have to ground it to enable.

author: netdudeuk
author_rank: Frequent Contributor
timestamp: January 13, 2023, 06:29:48 pm
content: So I bought a couple of those mentioned in the eBay links.They only took a few days to arrive and so far they look legit to me.I'll hook one up this weekend and see how it goes.If all's well, I'll order another couple.

author: netdudeuk
author_rank: Frequent Contributor
timestamp: January 31, 2023, 10:28:01 am
content: HiI came across a concerning thread last nighthttps://www.reddit.com/r/nixie/comments/uvxplc/just_throwing_this_out_there_this_is_untested/Does anyone have a view on this ?Thanks