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 Post subject: Re: Edge display/stepper voltmeter crystal frequency referen
PostPosted: Jan Thu 17, 2019 9:52 pm 
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Location: East Falmouth, MA
I'm pretty sure that I had to make the cables. They look somewhat original because among the parts I was given were spools of the hookup wire they used, so I was able to match the colors. Stuck inside my manual for the 4500 are two pieces of paper on which I wrote all the wire colors for the cables.

Barry - if one was to do your rev 01, you'd have to come up with a sound generator to simulate the stepper noises :lol: , not to mention a DVM chip that coild drive the bulbs in the display.

Pat - I have a complete manual for the 4500, including schematics. And, yes, I can try to help you sort out your broken wire. I strongly suspect that the guts of the all-in-one were the same as in mine; they probably just re-located the display for customers who didn't want the AC option.

I'd love to see photos of the solid state unit. I was given a bunch of transistors and recall being told they were from transistorized versions of the meter, but I don't recall ever seeing one.

The number of steppers would have depended on the number of digits in the display. I'm about to post some photos of some displays that I have, and you will see that there were also units with more digits. That would have required one more stepper.


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 Post subject: Re: Edge display/stepper voltmeter crystal frequency referen
PostPosted: Jan Thu 17, 2019 9:58 pm 
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Location: Southeastern Litchfield County, CT
Awesome - thank you! I shall excavate it tonight, and get some detailed photos up. I'd love to get this old beast back up and clacking away again.

-Pat

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 Post subject: Re: Edge display/stepper voltmeter crystal frequency referen
PostPosted: Jan Thu 17, 2019 9:59 pm 
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Location: East Falmouth, MA
Here are photos of some bare display units
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The next one must have been from a digital ohmmeter. Note the symbols in the right-hand place.
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The next one is similar to the ones in my meters.
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IMG_6712.jpg [ 122 KiB | Viewed 966 times ]


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 Post subject: Re: Edge display/stepper voltmeter crystal frequency referen
PostPosted: Jan Thu 17, 2019 10:00 pm 
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I'm getting excited! (don't tell) .... bringing back all those memories of my museum dislpay automation days ..... holy steppers, batman!

Sorry. I now return you to your regularly scheduled chat

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 Post subject: Re: Edge display/stepper voltmeter crystal frequency referen
PostPosted: Jan Thu 17, 2019 10:20 pm 
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I had this in my archive, apparently the founder of EI was a live fast-die young kind of guy :P He sold the company to Honeywell, and there are some later meters out there EI made that have both the Honeywell/Electro Instruments names on them.

Image

-Mark-

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 Post subject: Re: Edge display/stepper voltmeter crystal frequency referen
PostPosted: Jan Thu 17, 2019 10:39 pm 
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Location: East Falmouth, MA
Mark - do you have a date on that obit? I wonder if I met him back when. It would take some digging in my files to see if I have any records of names of the engineers I met.

The company address on the manual I have is 3794 Rosecrans St. I googled it and the place is now A&S auto Care. I wonder if it was a garage when EI moved into it? We've all heard of starting electronics businesses in a garage. Is this a case of starting a garage in an electronics business? :lol:


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 Post subject: Re: Edge display/stepper voltmeter crystal frequency referen
PostPosted: Jan Thu 17, 2019 10:49 pm 
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The newspaper article was from 1971. I couldn't ever find a single manual or Electro schematic online, and couldn't even locate a former address in San Diego. It's funny I was just looking at some photos in Cubdriver's gallery, and he looks to have a Honeywell 620B that was one of the last Electro designed pieces that was made at their factory in San Diego. Honeywell shut the plant down and moved these operations to Colorado.

-Mark-

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 Post subject: Re: Edge display/stepper voltmeter crystal frequency referen
PostPosted: Jan Thu 17, 2019 11:05 pm 
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Location: East Falmouth, MA
Just found an interesting article about DVM history, check out

http://hhuc.us/2016/files/Speakers/Rich ... istory.pdf

if you're interested.

I don't recall if it was the same person as the Kay who started NLS, but I remember Kay Laboratories in San Diego, which later became KinTel. They made closed circuit TV gear and at one time I had some of that too, also given to me during my science fair years (late 50's). One of the TV monitors had a very nice power supply in it. The construction of the monitor was modular so it was easy to take the power supply out and use it in one of my projects.


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 Post subject: Re: Edge display/stepper voltmeter crystal frequency referen
PostPosted: Jan Fri 18, 2019 2:05 am 
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I saw that article back when I was trying to research as much as I could about EI. I have come across several old Kin Tel/Cohu analog meters, but never any of their digital models that competed with EI and Non Linear Systems in the late 50's and early 60's. I believe that Cohu found the video business to be more lucrative for them after digital meters became more commonplace, and the company is still around today.

-Mark-

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 Post subject: Re: Edge display/stepper voltmeter crystal frequency referen
PostPosted: Jan Fri 18, 2019 2:42 am 
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Joined: Jan Tue 15, 2019 9:36 pm
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Location: East Falmouth, MA
I found another article
http://www.fundinguniverse.com/company- ... c-history/
Turns out I remembered slightly wrong - KayLab came from Kalbfell Lab, became KinTel and within a year or so was liquidated and bought by Cohu. Never had anything to to with the KAY who founded NLS, although KinTel & KayLab did make some test gear. The purchase by Cohu happened right about the time that I acquired the closed circuit tv gear and that might be why they were giving it away - it had the old company name on it.
Yes, Cohu is alive & well and has been making semiconductor inspection equipment for many years. The TV business is now CohuHD

Anyway, glad you enjoyed my photos

Clyde


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 Post subject: Re: Edge display/stepper voltmeter crystal frequency referen
PostPosted: Jan Fri 18, 2019 3:12 am 
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Ok, I dug the meter out and figured out which wire had come loose.

The loose wire is the blue one in the photo below, attached to the righthand terminal of the barrel shaped resistor affixed to the center bulkhead just above the lower right (loose) stepper relay.
Image

Here is a much tighter view, mainly showing the relay, but with the wire visuble at the top of the frame. I *think* it connects to one of the terminals in the rows closest to the bulkhead (adjacent to either the yellow or green wires). Looking it again in this photo, [s]it might have gone to the connection with the blob of solder on the third from left terminal next to the yellow wire[/s]. Never mind that last line - the broken yellow wire visible at the left edge of the picture went there. The blue one remains a mystery. Could you take a look/take a photo of yours and tell me where that wire goes?
Image

Thanks!!

-Pat

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 Post subject: Re: Edge display/stepper voltmeter crystal frequency referen
PostPosted: Jan Fri 18, 2019 8:29 pm 
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Joined: Jan Tue 15, 2019 9:36 pm
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Location: East Falmouth, MA
Hi Pat
Do these photos help?
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Attachment:
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This morning I got them both out and the first thing I did was vacuum out the remains of the sound deadening foam. Then I took a LOT of photos.

Let me know if you or anyone els on the forum would like to see more.


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 Post subject: Re: Edge display/stepper voltmeter crystal frequency referen
PostPosted: Jan Fri 18, 2019 10:49 pm 
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Unfortunately, the new photos don't quite show me where the wire connects to the relay. I've taken two more photos of mine, showing where I guessed the wire went, and connected it (first terminal on the second row away from the bulkhead). Would you please take a look at yours and see if I've put it (and for that matter, the yellow one, too) in the correct spot, and if not, let me know where on your meter it is connected? For reference, count the rows out from the bulkhead, and the terminals clockwise from the bottom when looking in at the bulkhead the relay mounts to. In my photo, the yellow wire would be first row, third terminal, and the blue be second row, first terminal.

Image

Image

Thank you for your help on this!

-Pat

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 Post subject: Re: Edge display/stepper voltmeter crystal frequency referen
PostPosted: Jan Sat 19, 2019 1:55 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 188
Location: Colorado Springs, Colorado
Here are some pictures of my 1960 vintage 8409 Electro Instruments DVM.
It uses hundreds of germanium transistors, 35 circuit boards, two choppers,
three relays and five Nixie tubes for the readout. The relays are used for range and
polarity switching. The choppers are used for converting DC voltages to AC for more
accurate amplification and less drift. It also uses the famous Bulova temperature
stabilized zener reference.


Attachments:
EI Voltmeter 001-1.jpg
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EI Voltmeter 002-1.jpg
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EI Voltmeter 003-1.jpg
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EI Voltmeter 004-1.jpg
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EI Voltmeter 005-1.jpg
EI Voltmeter 005-1.jpg [ 153.64 KiB | Viewed 923 times ]
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 Post subject: Re: Edge display/stepper voltmeter crystal frequency referen
PostPosted: Jan Sat 19, 2019 3:10 am 
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Thanks for the pictures of your meter Bob, that is definitely an interesting piece! Amazing how quickly things changed when the switch was made to solid state and all the buzzing steppers were gone! I have a HP/Dymec 2401A Nixie tube meter that is a hybrid tube/germanium transistor unit from '62. It has 5 tubes, 2 of which are Nuvistors, on an op-amp board HP sourced from Philbrick Researches. "Transition period" equipment always brings something interesting to the table.

-Mark-

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 Post subject: Re: Edge display/stepper voltmeter crystal frequency referen
PostPosted: Jan Sat 19, 2019 3:20 am 
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Very cool old instrument there, Bob. Thanks for the pics.

-Pat

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 Post subject: Re: Edge display/stepper voltmeter crystal frequency referen
PostPosted: Jan Sat 19, 2019 3:45 am 
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Joined: Jan Tue 15, 2019 9:36 pm
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Location: East Falmouth, MA
Bob: very cool meter.

Pat: you've got it correct, both blue & yellow wires

Clyde


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 Post subject: Re: Edge display/stepper voltmeter crystal frequency referen
PostPosted: Jan Sat 19, 2019 3:59 am 
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ctyndale wrote:
Bob: very cool meter.

Pat: you've got it correct, both blue & yellow wires

Clyde


Awesome, thank you for the confirmation!

-Pat

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 Post subject: Re: Edge display/stepper voltmeter crystal frequency referen
PostPosted: Jan Sat 19, 2019 4:03 am 
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Joined: Jan Tue 15, 2019 9:36 pm
Posts: 37
Location: East Falmouth, MA
So here are some photos of another style of early digital display. It uses incandescent lamps and a small projection scheme so that all the digits are in a single plane.
I have two models in my collection - one is numbers and the other is all characters.
Model 10001 is the character unit
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Model 10000 is the number version
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Attachment:
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 Post subject: Re: Edge display/stepper voltmeter crystal frequency referen
PostPosted: Jan Sat 19, 2019 4:25 am 
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Joined: Jan Tue 15, 2019 9:36 pm
Posts: 37
Location: East Falmouth, MA
Pat: Happy to help. Good luck with the rest of the restoration.

Here is a copy of the first page of the theory of operation for the 4500. Should be the same for all the stepper based models.
Attachment:
4500 manual fig 4-1.jpg
4500 manual fig 4-1.jpg [ 118.47 KiB | Viewed 915 times ]



If the unit has to count up to reach balance, the logic is relatively straightforward. Because the steppers are unidirectional, it gets a little more complex if the unit has to count downwards. The logic for that is all in the wiring of the steppers.

I am working on scanning the manual, and another member has offered to help with the large schematic drawings. Stay tuned. Once scanned, i'm happy to make it available.

Clyde


Attachments:
EI 4500 fig 4-1.pdf [109.96 KiB]
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EI 4500 fig 4-1.pdf [109.96 KiB]
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