Journal Alioth's Journal: [nixies] New interconnect scheme 2
One topic that hit NEONIXIE-L in the last couple of days is the subject of building our PCBs out of various kinds of perfboard. Someone had some tri pad board and some wider ICs, and was wondering how to hook up his interconnects since one row of IC pins was on the last row of holes. I suggested soldering the interconnects on the underside of the board - on the 'inside' of where the IC lies (on the other side of the board), with a nice hot iron so you don't have to spend too long putting on the solder, and melt the insulation. (I have been using up until now 'wire wrap' type wire for the interconnects).
Someone else had a much better suggestion though - use transformer wire. His work is truly beautiful - see it here:
http://elm-chan.org/docs/wire/wiring_e.html - doing SURFACE MOUNT stuff without a factory made PCB.
Since I have a spool of transformer wire which I was using to make inductors, I've been trying it. My work so far is nowhere near like that - indeed, it's a bit messy. After some trial and error (mostly error) - I discovered the best way to do it is thus:
1. Make a molten blob of solder on the soldering iron tip.
2. Run the transformer wire into the blob, so it goes right inside the blob. Do it for about 2 millimetres or so. This strips off the insulation and makes it back up the wire, as well as tinning the now exposed end. The wire MUST go in the blob or it just chars and smells bad instead of stripping.
3. Solder the end to the board. BUT - don't do 'pin through hole' - Surface mount it - where the pin from the IC socket comes through, just press the soldering iron tip against its blob of solder, and let the tinned end sink in. Then remove the soldering iron, and curse as the wire conducts the heat and burns your fingers (but don't let go until you're sure the solder is properly solid).
4. Cut the other end of the wire and repeat to connect it to its destination.
Now I'm starting to get some practise, it is MUCH faster than using wire wrap wire. Not only is it faster, but you can get a significantly higher wiring density. The enamel insulation 'solder resists' and is quite heat resistant, so you don't risk melting it quite so much like you do with the plastic insulation on wire wrap wire. Perhaps one day I'll be able to make a work of beauty like in the linked pictures. (I will try and get a reel of polyurethane insulated transformer wire next time - I think he was omitting the solder blob wire stripping stage with that).
I also got some more nixies today - a lot of fifty NH-12B tubes. One thing I can be thankful for the defunct Soviet Union for is massively overproducing things like this - the tubes were less than a buck a piece (Western tubes, on the other hand, usually will cost you 7 or 8 bucks a piece because they are getting like hens teeth now). It's my second purchase from the Ukrainian seller - he specialises in all kinds of tubes, not just nixies - but valves (vacuum tubes) for audio amplifiers too.
These nixies are a bit different from the IN-16 tubes I'm using on the current project. The -16s are 'vertical' (flying leads out of the bottom, and the digits are in the same plane as the leads). The -12s are 'front view' - so the pins are directly behind the digits. Also, the pins are like those on valves (vacuum tubes) - instead of long flying leads, they are the thick pins that go into sockets (so I also bought a lot of 50 sockets to go with the tubes). The new tubes have slightly larger digits than the ones I've got on my current project. Interestingly, unlike the IN-16 which has the digit 5 formed of a proper 5, the 5 on the IN-12B is an upside down 2! Sort of gives it a rather unique aesthetic (as if nixies didn't have a unique aesthetic to start with).
So my big debate: my next project will be microprocessor based (I have three Z80 processors on hand, and a couple of 2kbyte static RAMs to experiment with). Should I get a graphic LCD - 256x128 pixel LCDs are available for about 35 quid from RS Components - or should I use a nixie display?
Nixies (Score:1)
Two things (Score:2)
First, you're right -- that guy's work is just gorgeous. Neat stuff.
Second, I've really been enjoying reading what you've written about this project, even though I don't understand a tenth of the electronics. I like the detail you've been putting into your posts; I like that (I imagine) you're trying to help out someone else by showing what you've done, what works and what doesn't. I think that willingness to share is a Good Thing.