EEVblog #1138 - Systron Donner Counter Teardown - Page 1
Forum section: electronics / general

author: EEVblog
author_rank: Unknown
timestamp: October 23, 2018, 09:42:15 pm
content: Teardown TuesdayAn early 1970's Australian made Systron Donner Nixie tube display counter/timer.

author: N2IXK
author_rank: Frequent Contributor
timestamp: October 23, 2018, 10:44:06 pm
content: Nice! If you take the "recycle time" control off the "infinity" setting, the gate should run repeatedly without manual reset....

author: johnlsenchak
author_rank: Frequent Contributor
timestamp: October 23, 2018, 11:29:09 pm
content: To think, if Dave didn't take this unit out of the dumpster, all that gold would have ended up in a landfillHow much money in gold do you think those boards have on them when it comes to the Aussie dollar?Good day mate

author: richnormand
author_rank: Unknown
timestamp: October 24, 2018, 02:09:39 am
content: Quote from: N2IXK on October 23, 2018, 10:44:06 pmUnless you have the remote set in the back (my 6054B is like that).Also the oven ref will not respond to adjustments until an hour or so while it stabilize. You also need a pretty long screwdriver to reach the adjustment pot that is surrounded with foam.Extender boards are most likely for board adjustments that are unreachable when fully inserted.EDIT:Looks like I was wrong. Dave has a different OCXO than I have.See post #8 herehttps://www.eevblog.com/forum/blog/eevblog-1139-tcxo-oven-oscillator-repair/

author: EEVblog
author_rank: Unknown
timestamp: October 24, 2018, 03:25:19 am
content: Quote from: N2IXK on October 23, 2018, 10:44:06 pmYes, but it's not very usable. The fast mode is completely unusable, you never get a displayed reading long enough to read it, and the slow mode is agonisingly slow to auto-refresh.

author: Dr. Frank
author_rank: Super Contributor
timestamp: October 24, 2018, 01:40:09 pm
content: Very nice tear down and functionality check.The time base selector has a 10 nsec setting, therefore I assume the internal time-base PCB to deliver 100MHz, not only 10MHz.The circuit contains a rather simple 10MHz oscillator on the right, but there's that MC3060, which might be an ECL dual FF, similar to 74H74, so inside that metal can part might be an ECL PLL circuit (int and ext) to 100MHz.There's also that -5.2V supply, which indicates more fast ECL ICs inside the counter.So maybe the inputs work up to 100MHz also.Obviously they use two distinct mains transformers, one permanently operating for the OCXO, and the bigger one, switched, for the counter itself.I also ponder about these both osc. inputs on the rear, ext./int Time Base and STD Freq Input, where to feed the OCXO 10MHz in. I did not catch your description in the video correctly..Anyhow, that TTL grave reminds me of my own counter build in the 70 ties, but already with the higher integrated Mostek MK50398 counter / latch / display driver and 7 segment LED.It had a 7th digit, for > 10MHz counting, and a period mode also, to get higher resolution for low frequencies, by dividing either input frequency, or time base / gate time.That's obviously also provided on the Systron Donner counter, when you use B-input and period mode.Frank

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 24, 2018, 02:28:19 pm
content: Lots of classic logic!Just one thing: I'm disappointed you didn't do something Lucas-related for number 1138!Tim

author: edpalmer42
author_rank: Super Contributor
timestamp: October 24, 2018, 04:43:08 pm
content: Quote from: EEVblog on October 24, 2018, 03:25:19 amI've worked with old counters that have a Recycle Time control. It's a pot. Turn it clockwise and the display hold time decreases. Adjust it to a convenient setting. Looks like the fast and slow switch gives you two speed ranges. Doesn't this one work like that?

author: tchicago
author_rank: Regular Contributor
timestamp: October 24, 2018, 05:29:36 pm
content: Quote from: T3sl4co1l on October 24, 2018, 02:28:19 pmA mix of DTL, TTL and ECL logic. DTL did not need much of decoupling capacitors as it has a "soft" switching. TTL did need them as the TTL logic gates have current consumption spikes when the gate state is switched. That is due to both high and low output transistors being partially open during the transition.

author: bitwelder
author_rank: Super Contributor
timestamp: October 24, 2018, 07:50:27 pm
content: I hope Dave will use this beauty next time he needs to pick a giveaway winner.

author: SilverSolder
author_rank: Super Contributor
timestamp: October 25, 2018, 12:16:54 am
content: Love the smell of leaded solder in the morning!There is something deeply cool about Nixie tubes (any light emitting gas discharge technology actually!).