OT - ElectroMechanical 7-seg clock

[Steven Donaldson]

I saw this clock online over the weekend and thought it looked pretty neat.  Not nixie, but thought there might be some appreciation for flip displays - 

https://imgur.com/a/E98sq

Displays:  (no affiliation, just the first listing I saw)  https://www.ebay.com/itm/7-segment-1-Ferranti-Packard-electromechanical-display-/160945344354

[Manuel Azevedo]

I've bought these displays with the idea of making a clock like this.

Very nice execution. Looks very nice. 

[Dylan Distasio]

Love it!  Thanks for posting. 

--
You received this message because you are subscribed to the Google Groups "neonixie-l" group.
To unsubscribe from this group and stop receiving emails from it, send an email to neonixie-l+unsubscribe@googlegroups.com.
To post to this group, send email to neoni...@googlegroups.com.
To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/CAOXC3DGU1%2BHvXRwa0h3VAo57cMFd0pVuVEMk59UwWpoTkpVqqg%40mail.gmail.com.
For more options, visit https://groups.google.com/d/optout.

[gregebert]

How noisy are these displays ?

Years ago I had a flip-type digital clock (100% mechanical), without a case , and it was somewhat annoying when I was trying to fall asleep.

[Terry S]

I would say this is on-topic, per the charter. 

Neat displays, I may have to order up a set. 

Terry

[Steven Donaldson]

I have no idea, but was also wondering how noisy they were. I just found it on reddit, didn't actually build it.

On Jan 16, 2018 1:53 PM, "gregebert" <greg...@hotmail.com> wrote:

How noisy are these displays ?

Years ago I had a flip-type digital clock (100% mechanical), without a case , and it was somewhat annoying when I was trying to fall asleep.

--

You received this message because you are subscribed to the Google Groups "neonixie-l" group.
To unsubscribe from this group and stop receiving emails from it, send an email to neonixie-l+unsubscribe@googlegroups.com.
To post to this group, send email to neoni...@googlegroups.com.

To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/893b28fe-95a6-4f19-a7eb-743f3869ef04%40googlegroups.com.

[Manuel Azevedo]

Well, there still are some gas stations around here with these displays on the pumps. They are quite noisy - enough to make you not have one in your bedroom, even if it’s just a 4 digit one that only changes every minute. Imagine a 6 digit one... probably not even in an office.
Still, they look very cool!

[H. Carl Ott]

On Jan 16, 2018 1:53 PM, "gregebert" <greg...@hotmail.com> wrote:

How noisy are these displays ?

Years ago I had a flip-type digital clock (100% mechanical), without a case , and it was somewhat annoying when I was trying to fall asleep.

Pretty darn noisy. Years ago I did a clock design with some of these displays. 

In the end I had to program an on /off timer so that it would shut up at night and people could sleep. 

--
You received this message because you are subscribed to the Google Groups "neonixie-l" group.
To unsubscribe from this group and stop receiving emails from it, send an email to neonixie-l+unsubscribe@googlegroups.com.
To post to this group, send email to neoni...@googlegroups.com.

To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/893b28fe-95a6-4f19-a7eb-743f3869ef04%40googlegroups.com.

[Mike Mitchell]

i liked the displays so much I bought a sets.  I thought I'd be smart and tried some push-on connectors but they ended up breaking the solenoid wires.  I had to order another set and then solder each connection.

I finished my version over the summer, using L293 half-bridges as drivers.  I included a GPS module for time sync and a Bluetooth module to set options.

The displays are noisy so I only built a four-digit clock.  I also have a "night time" mode where the displays go dark until the morning.

Mike Mitchell

[Terry S]

I like it Mike -- care to share your design?

Terry

[Mike Mitchell]

On Sunday, December 23, 2018 at 3:37:00 PM UTC-5, Terry S wrote:

I like it Mike -- care to share your design?

Terry

When I saw the https://imgur.com/a/E98sq posting I contacted "iamatesla" and asked about a kit.  I also asked about through-hole instead of SMD. Those conversations didn't lead anywhere, so I examined his schematic and came up with my own design.

Rather than using individual MOSFETs for the H-bridge drivers, I settled on the L293D quadruple half-H drivers. I multiplexed the displays in standard segment/digit fashion, so I only needed four chips, two for the segments (7 half-drivers) and two for the digits (4 full drivers). Multiplexing also means adding 56 diodes, as the solenoids are bi-directional and not uni-directional like LEDs. The solenoid pulse lasts only a millisecond, so the diodes have to have a fast recovery time and be able to handle the inductive transients.  I used these: https://www.vishay.com/diodes/list/product-88736/

I split the clock into two boards to fit better in a case.  One board has all the drive electronics, including an off-the-shelf 5v to 19v DC-to-DC converter.  The second board has a Teensy 3.2 processor, a bluetooth module, two eight-bit shift registers, a 3.3v to 5v level shifter, and connections for a GPS module.  I didn't put the GPS module on board because I'm using its patch antenna and I didn't want the display board to block the signal.  The GPS module sits above the display board.

I've done enough of this type of work that I didn't draw out the schematic for the teensy, GPS, and bluetooth connections.  I'm including a photo of a partial driver board schematic and some other photos of the construction.  If you look at the photos you can tell that I built two of these clocks.

I'm happy to answer any questions.

Mike Mitchell

[Michail Wilson]

Think you might come out with a kit?

 

Michail Wilson

206-920-6312

--

You received this message because you are subscribed to the Google Groups "neonixie-l" group.

To unsubscribe from this group and stop receiving emails from it, send an email to neonixie-l+...@googlegroups.com.

To post to this group, send email to neoni...@googlegroups.com.

To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/a43f091a-951e-4f99-8db0-c74e0e56a212%40googlegroups.com.