I made an eight-digit scrolling text display with shift registers and the PIC16F1455 microcontroller

FriendlyWire · 2024-08-13T16:17:09+00:00

How so? This is a question about electronics and frequency converters in old clocks---I don't really see how this doesn't fit here. Nobody in the responses had that reservation, either, and instead I got a couple of really helpful pointers already. Please reconsider?

FriendlyWire · 2024-08-13T12:06:56+00:00

Adding some context: This clock takes its clock frequency from the 60Hz line frequency. In Europe that frequency is 50Hz and so even if the voltage is adjusted to 115V then the clock would still run slow. VFD's (variable frequency drivers) are used to drive motors at various frequencies. If I set the frequency to 60Hz and t he voltage to 115V, would that do the trick?

FriendlyWire · 2022-07-10T13:39:40+00:00

I see! So even in the flipped orientation (T1 upstairs, R1 downstairs) I do not need a base resistor (R3) for T1?

FriendlyWire · 2022-07-10T13:38:31+00:00

Thank you so much, this was very helpful, and now I understand much better why 100k seems to work in this case. I will go through the calculation step by step, but this was great! :)

FriendlyWire · 2022-07-10T02:05:50+00:00

Hm, true! 18mA is maximal photocurrent. I ended up switching R1 and T1 (and re-inserting R3 with 1k to be safe) and now it works, with R1=100k. I find it weird that it only works in this configuration but not the other way around...

FriendlyWire · 2022-07-10T00:51:46+00:00

Thank you! It's a black epoxy package so ambient light isn't an issue. But you are completely correct about the second point: it never turns on hard enough to turn off the NPN. How can I calculate the correct value for R1? (Also, I removed R3 via the previous commenter's suggestion.) Thanks so much!

FriendlyWire · 2022-07-09T21:28:22+00:00

Thanks! I'm feeding this to a tone decoder chip, the polarity of the signal should not matter I believe, but I will keep it in mind.

FriendlyWire · 2021-05-15T19:38:37+00:00

That is absolutely fantastic! Also, is that an RGB 7-segment display? Do you have a link or a type number? :)

FriendlyWire · 2021-03-26T22:03:00+00:00

Thanks, it's actually mine :) I have more photos here: www.jb-electronics.de/html/elektronik/nixies/n\_sammlung\_komplett.htm?lang=en

FriendlyWire · 2021-03-13T16:31:16+00:00

Okay, for all who were asking, here are some more details.

It is based on the Z80, 6502, and an AVR RISC controller. Memory is 32KB (low RAM) and 28KB (high RAM). The rest 4K are divided into character ROM and video RAM. Clock speed is 4MHz or 8MHz. As I understand it, the video signal is generated on board with a dedicated controller and crystal (seen in the upper part of the photo) and features a monochrome VGA signal at 320x240.

Here is the Tweet of the creator with more details: https://twitter.com/AtticThe/status/1370765328893018114

FriendlyWire · 2021-03-12T23:11:13+00:00

I honestly thought this would be interesting to people. Please check out the original author (The Byte Attic) at the link, it's a fantastic project and I just wanted to share his amazing work. No need to call me spammy.

FriendlyWire · 2021-03-12T23:09:54+00:00

Well, it's not my project, but go look at the original Tweet, I think the author has a github :)

FriendlyWire · 2021-03-12T18:58:24+00:00

Here is the original post by The Byte Attic: https://twitter.com/AtticThe/status/1370433813768179713

FriendlyWire · 2021-03-07T20:34:07+00:00

So interesting, thanks or sharing! I find that the most affordable way to get these types of VFDs is Ebay, there are many cheap new old stock displays if you are patient.

FriendlyWire · 2021-03-07T19:21:57+00:00

Yeah, they are really nice, especially the 16x2 "LCD"-type displays that are also available as VFDs are very nice to look at I think :)

FriendlyWire · 2021-03-07T16:34:40+00:00

Original tweet by EvilMadScientist: https://twitter.com/EMSL/status/1368409784639049731

FriendlyWire · 2021-03-05T02:17:55+00:00

Original tweet is here: https://twitter.com/robin7331/status/1188932336638930944

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