I have purchased a module with a VF display and keypad on it, suitable for interfacing with a 6502 system (it has a Rockwell 10937 VF display controller on it, that can be controlled with two pins, clock and data).

It has a 16 character segmented VF display and a 28 pin keypad, it used to be part of a Veri fone credit card verification terminal

The trouble is that the VF display requires -30v, which seems relatively difficult to generate. My best guess is a transformer with -45-0-45 taps and then a regulator from there. Is that how this was usually done back when these displays were in common use?

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http://WilsonMinesCo.com/ lots of 6502 resources
The "second front page" is http://wilsonminesco.com/links.html .
What's an additional VIA among friends, anyhow?

I have not been able to locate a Datasheet or any documentation on the display. It is a Futaba 16-SY-03Z. I have a photocopied schematic of the Veri fone module, that is how I know it needs -30v, but it's just an input pin on the schematic.

Trying a different path, I think this for a Verifone ZON, but I can't find pictures of that one, only the ZON Jr. This apparently has +5 and -5v on the main board, and it's display board has:

The keypad / display board has these chips:
U3, a 10937P-40 Vacuum fluorescent driver
U2 a TL074CN quad OP-Amp
A piezo speaker
High voltage generator circuit for the vacuum fluorescent display (it's got to have one, plus the round inductor near the top is a dead give-away).


according to https://jhallenworld.blogspot.com/2012/08/reverse-engineering-verifone-zon-jr-xl.html.

So one possible path to solve this problem is to get a ZON Jr and reverse engineer that high voltage generator circuit?

A ZON Jr display board would make quite a good user interface for a small 6502 system.

_________________
http://WilsonMinesCo.com/ lots of 6502 resources
The "second front page" is http://wilsonminesco.com/links.html .
What's an additional VIA among friends, anyhow?

Maxim has MAX774 (or MAX775 or MAX776) for this kind of application. If you hook the output directly to the feedback pin, you get -5V, -12V, or -15V (depending on the part number you ordered), but you can also put a voltage divider on the feedback line to get larger output voltages. You will need to add a P-channel FET, an inductor, a schottky or SBR diode, and some input and output and bypass caps. The datasheet offers reasonable guidance in selecting these other components.

Hi, if I can add a few cents worth...
I had to design a simple modem tester for the factory production lines, and it had to actually generate the ring pulses and provide the DC telephone power. I remember that for reliable ring I had to generate pulses in the 45V region (but very low power). A useful circuit that I used was a lowly 555 with a chain of Diodes and Caps at the output to create a voltage "doubling" ladder. It worked very well, and could give nasty jolts if you forgot it was running when your fingers were in the way! I cant recall the standard name for the type of AC voltage doubling ladder, but it is well documented on the net. If you cant find it, I think I still have my notes from, erm, well over 20 years ago (around the time I joined this forum BTW)

Have fun!

My kim 1 was equipped with a similar type of display, but I was lucky enough to have scavenged the display with it's HT board. I just had a thought : many VCRs had similar displays - you might find something worth cannibalizing ?

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Glenn-in-France

I'm thinking that that may be the best way forward. Get a ZON Jr as they are cheap and easy to get and have a look at the circuit on there, but even easier just use the display board from that. This could be a good plan if people would like a VF display, the displays themselves are quite expensive on eBay, but if you buy a ZON Jr it comes with everything needed.

Hmm. The first hit I got on German ebay for Xon Jr produced this:

But after a while it got down to business, and told me I can have one for ten euros or so, if I'm prepared to pay another thirty bucks to import it from the US. I guess they're a US-generic part.

Neil

You probably need to search including Verifone, or Veri fone as it was back then. I've purchased one to pull apart and see how it's done, should be interesting, and as I said before, they could be a good source of 16-character VF displays if anyone is interested in them. I guess a character LCD is much easier now, but old computers like the Rockwell AIM-65 used displays a bit like this and they are getting very expensive now. Since they are very easy to interface with, apart from the power requirements, I'll probably try and get it working with my RSC-Forth computer.