The Nixie That Almost Was - Dialco Neon 7-Segment Conversion Display

So diode steering is a thing. Many moons ago when I was a teenager, I built a switch that latched output that used a stack of diodes to reset the latches. I guess that was diode sweering.

Those are beautiful. They remind me of the over size 7 segment displays you designed.

Jessica McIntosh

Yea, cathode death is a problem with all neon displays. I've had lots of neon lamps in power strips and appliances dim and then fail to strike anymore at some point.

Fran Blanche

I danno - the Panaplex is really awesome.

Fran Blanche

Not way smarter, way older.

Now you're cookin'

I love that diode steering sandwich.

David Peaker

While these displays are now as rare as dentures for chickens, I believe there was a window when they were used in significant numbers. If indeed they were intended to take on Nixie tubes, they do have significant advantages. Nixie tubes were expensive and even the socket was expensive. Moreover, they were *dim* and washed-out badly with a narrow viewing angle. The Dialights could be populated with different gas-discharge lamps, not just the neon-filled NE-2. “Back in the day”, physically similar lamps could be had with different gas mixtures, as well as the addition of phosphors on the tube inner surface which when pumped with an argon discharge would yield colors. I particularly remember a “green NE-2” which matched the color of a 1629 “magic eye” tube often used as a tuning indicator on radios. The “green NE-2” lamps illuminated the frequency dial. As for performance fade over time, an NE-2 will light over a considerable current range with brightness a function of current. If driven hard enough, the cathode element (assuming DC power) will sputter itself onto the inside surface of the glass making it more opaque over time. Lamps replaced for this reason have a mirror finish seen from outside with little light escaping. Based on the construction, I think you have original engineering prototypes. The 2.5D sandwich construction of the decoder was common in high density packaging of the day. It also helped with vibration resistance and supported potting of the assembly for environmental reasons. The part that looks like a prototype to me is the blue “coupler” pad between the lamp board and the decoder-driver. For instance, real production tooling wouldn’t use lots of little parts like steel springs. The calculator business popularized LCDs and that in turn popularized “elastomer zebra strips” which provided a soft mounting pad but with “directional conduction” which eliminated wire attachment of LCDs. The blue pad with the similar function looks like something banged-out by a clever MechE but has not yet gone though “design for manufacturing”. Dialight is still around in some form. It might be worth a poke letting them know what you have and whether they have any info. Great job, though. As befits someone of your considerable experience, you have Mad Scrounging Skillz!

Mike O'Dell

Another great video on a display idea that didn't go anywhere, yet someone put a lot of effort into its design. Good luck replacing a diode in that circuit board sandwich! I work for a company that builds a lot of aircraft testing rigs and I have noticed that neon lights do not have an indefinite life. We used a great deal of them on power panels to show the presence of AC power and expected them to be maintenance free. After about 5 years of being on 24/7, they start to dim and by 10 years they really don't emit light at all.

Matt Wietlispach

To imagine that LEDs were right around the corner and all you'd need was 5V instead of 140V to light a display.

lohphat

Wow. The extent they used to go to for a simple digit display is amazing.

William Alsing

Oh that nixie glow! So beautiful 😲

Fran, you found another gem. Thanks for sharing!

David Blake

I wish Heathkit had used these instead of Panaplexes... Panaplices? At least then they could be serviced with new neon lamps.

It always amazes me - who designs this stuff?! People way smarter than me.

One could totally make a clock out of that... using the vertical part of the + for the hours tens place... a little insulating tape on the contacts for the arms of the + would do it. it would certainly be unique.

I missed the live stream and haven't had time to go back and watch it yet, but after watching this I will do soon.

Dr Andy Hill

Cool

The construction technique with components standing between two PCBs I believe is called "Cordwood": https://en.wikipedia.org/wiki/Printed_circuit_board#Cordwood_construction

BobC

I just *love* your electronics archaeology...

Mark Wilkes