Author Topic: What kind of reference is this??  (Read 5798 times)

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Offline e61_phil

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What kind of reference is this??
« on: February 17, 2017, 07:05:13 AM »
Hi,

today I received an old data precision 8200 calibrator in quite bad condition. Everthing was flying around in the housing. Therefore, I opened the box before switching it on. There were some modifications made.

Most interesting one is the aluminium box. This box was connected to the place, where the old reference diode was. Inside this box there are 4 "things" with 4 pins. I can't see any labeling on these 4 parts.

Does anyone know what kind of reference this is? And where does it come from?

Thanks
Philipp
 
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Online Vgkid

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Re: What kind of reference is this??
« Reply #1 on: February 17, 2017, 07:15:56 AM »
Possibly a naked lm399. I have an ancient zener GE 4-pin voltage reference floating around somewhere, I will see if I can find it tonight.
If you own any North Hills Electronics gear, message me.
 
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Online Andreas

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Re: What kind of reference is this??
« Reply #2 on: February 17, 2017, 07:16:45 AM »
Hello,

Could be naked LM399s like here:

http://www.gellerlabs.com/MGTA%20kits.htm

With best regards

Andreas
 
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Offline e61_phil

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Re: What kind of reference is this??
« Reply #3 on: February 17, 2017, 07:20:34 AM »
I opened one of my LM399 and the size and look will fit. Thanks!

The box, with the PCB and the foam doesn't look like selfmade. Any ideas where it can come from?
 

Offline Conrad Hoffman

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Re: What kind of reference is this??
« Reply #4 on: February 17, 2017, 08:47:36 AM »
Don't know, but I have an 8200 and it's one of the more useful things on my bench. Well worth putting into good shape. Mine uses a garden variety LM399, but it stays within a couple ppm for years at a time. The rotary switches on mine are a nightmare to keep working. DeOxit hasn't helped much. My next attempt will be total immersion of the switch board in the ultrasonic cleaner. I'm assuming it's the switches, not the following circuitry, but scoping the switches hasn't convinced me they're as bad as they seem.
 

Offline e61_phil

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Re: What kind of reference is this??
« Reply #5 on: February 17, 2017, 08:53:54 AM »
I had only a quick test until now. 10V and 1V Range seems to work. The 100mV Range has some problems. 100mA isn't tested yet. One digit is totally off.

I think this should'nt be a very big problem to get this thing up and running.

About stability: I would prefer an original shape of the unit. Therefore, I will install a new LM399 in the right place.
The 20bit DAC is really interesting. I've never thougt that this will work for 6.5 digits :)
 

Offline lowimpedance

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Re: What kind of reference is this??
« Reply #6 on: February 17, 2017, 09:41:39 AM »
 So the PCB looks like some commercial product, even has a QA stamp !?. Any way if it is indeed 4 X lm399 (averaging ?) maybe it would be worth evaluating it first to see if it is actually going to be better than a single new LM399 especially since they would be nicely aged and also nicely housed.
You call that current ?.......
I'll show you current !
 the odd multimeter or 2 or 3 or 4...or........never mind
 

Online Vgkid

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Re: What kind of reference is this??
« Reply #7 on: February 17, 2017, 11:09:32 AM »
So the PCB looks like some commercial product, even has a QA stamp !?. Any way if it is indeed 4 X lm399 (averaging ?) maybe it would be worth evaluating it first to see if it is actually going to be better than a single new LM399 especially since they would be nicely aged and also nicely housed.
I only see 1 LM399 sized component(to-5)
I do see 4 to-18 transistors, possibly for the zener current reference.
If you own any North Hills Electronics gear, message me.
 

Offline lowimpedance

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Re: What kind of reference is this??
« Reply #8 on: February 17, 2017, 12:47:56 PM »
It could be just the one, not having seen one without its coat on.
I based previous my comment from viewing the Geller link posted and the rather similar looking lm399 part there without a casing to the four shown in the picture.  :-//

Perhaps a closer picture of each part might shed more light. bit hard to tell anything from the one posted. (particularly with my aging eyeballs  :P)
« Last Edit: February 17, 2017, 12:51:12 PM by lowimpedance »
You call that current ?.......
I'll show you current !
 the odd multimeter or 2 or 3 or 4...or........never mind
 

Offline e61_phil

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Re: What kind of reference is this??
« Reply #9 on: February 17, 2017, 05:38:50 PM »
As already mentioned the size of these 4 "elements" will perfectly fit to a nacked LM399.

I will try to make better pictures this evening and I will power it up without this case. If it is really a LM399 it should run quite hot. I will also have a look at the traces and measure some voltages.
 

Offline eurofox

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Re: What kind of reference is this??
« Reply #10 on: September 11, 2017, 06:25:59 PM »
As already mentioned the size of these 4 "elements" will perfectly fit to a nacked LM399.

I will try to make better pictures this evening and I will power it up without this case. If it is really a LM399 it should run quite hot. I will also have a look at the traces and measure some voltages.

It is a LM299.

 

Offline e61_phil

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Re: What kind of reference is this??
« Reply #11 on: September 11, 2017, 06:39:28 PM »
Quote from: eurofox
It is a LM299.

No
 

Offline branadic

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Re: What kind of reference is this??
« Reply #12 on: September 11, 2017, 08:26:24 PM »
Quote
I will try to make better pictures this evening and I will power it up without this case. If it is really a LM399 it should run quite hot. I will also have a look at the traces and measure some voltages.

I'm missing the better pictures and the promissed voltages ;)

-branadic-
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Offline e61_phil

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Re: What kind of reference is this??
« Reply #13 on: September 11, 2017, 10:21:38 PM »
Quote
I will try to make better pictures this evening and I will power it up without this case. If it is really a LM399 it should run quite hot. I will also have a look at the traces and measure some voltages.

I'm missing the better pictures and the promissed voltages ;)

-branadic-

Sorry, I already replaced this DIY reference with a LM399 and brought everything to the original state.

Voltage was in the range of the LM399. Nevertheless, I had to change the resistors (R9 & R10), because the new reference brought it out of the trimming range.
 

Offline eurofox

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Re: What kind of reference is this??
« Reply #14 on: September 11, 2017, 11:11:38 PM »
Quote
I will try to make better pictures this evening and I will power it up without this case. If it is really a LM399 it should run quite hot. I will also have a look at the traces and measure some voltages.

I'm missing the better pictures and the promissed voltages ;)

-branadic-

Sorry, I already replaced this DIY reference with a LM399 and brought everything to the original state.

Voltage was in the range of the LM399. Nevertheless, I had to change the resistors (R9 & R10), because the new reference brought it out of the trimming range.

I bought the same instrument with some problems, I have the same problem with the resistors 9 and 10, I cannot get the voltage in range with R12 and the reference is the original LM299 that is quite similar to the LM399.

I have problems as well with this par that I cannot get into range, I suspect the operation amplifier, I order new parts before continuing my investigation.




 

Offline e61_phil

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Re: What kind of reference is this??
« Reply #15 on: September 12, 2017, 12:01:34 AM »
I bought the same instrument with some problems, I have the same problem with the resistors 9 and 10, I cannot get the voltage in range with R12 and the reference is the original LM299 that is quite similar to the LM399.

I have problems as well with this par that I cannot get into range, I suspect the operation amplifier, I order new parts before continuing my investigation.


In my unit somebody replaced the original reference by an DIY construct. Therefore, I said no to the LM299. (Was a bit short, sorry)

I calculated R9 and R10 (which are in series) in respect to the measured 10V output.

If I can help you with any measurement in my working 8200, please contact me.
 

Offline branadic

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Re: What kind of reference is this??
« Reply #16 on: September 12, 2017, 03:32:36 AM »
Quote
In my unit somebody replaced the original reference by an DIY construct. Therefore, I said no to the LM299. (Was a bit short, sorry)
I calculated R9 and R10 (which are in series) in respect to the measured 10V output.
If I can help you with any measurement in my working 8200, please contact me.

Why? 4x LM399 should result in half the noise of a single LM399, shoulnd't it? Or did you carefully select a LM399 for good stability and smallest noise?
At the end a LM299 and a LM399 are nothing but a LM199 with downmarket specifications aka selection.

-branadic-
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Online Vtile

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Re: What kind of reference is this??
« Reply #17 on: September 12, 2017, 03:58:10 AM »
Would be interesting to get the circuit drawing of the supposed DIY reference. For my eyes it looks anything else than DIY.

Could it be 4 zeners (of some type) and OP(2)07 (in hermetic TO-99) circuit?
« Last Edit: September 12, 2017, 04:16:01 AM by Vtile »
Pick your point and call it as a ground.
 

Offline MK

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Re: What kind of reference is this??
« Reply #18 on: September 12, 2017, 04:25:19 AM »
It looks to me like it is 4 of the same reference in a set, LM199, LM299, and LM399 are all the same basic die from the same wafers, just selected for a different spec. If they do not have any popcorn noise they will all settle down to LM199 stability when old enough.
 

Offline e61_phil

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Re: What kind of reference is this??
« Reply #19 on: September 12, 2017, 06:28:27 AM »
Quote
In my unit somebody replaced the original reference by an DIY construct. Therefore, I said no to the LM299. (Was a bit short, sorry)
I calculated R9 and R10 (which are in series) in respect to the measured 10V output.
If I can help you with any measurement in my working 8200, please contact me.

Why? 4x LM399 should result in half the noise of a single LM399, shoulnd't it? Or did you carefully select a LM399 for good stability and smallest noise?
At the end a LM299 and a LM399 are nothing but a LM199 with downmarket specifications aka selection.

-branadic-

I want to have it in an original state. And look onto my first picture. There was a very nasty perfboard (?). The board was already cooked under the rectifiers. Nothing, I would like to run over night in my house with my family.

For my eyes it looks anything else than DIY.

With DIY I meant the whole setup. The reference module itself might be taken from anywhere.
 

Offline branadic

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Re: What kind of reference is this??
« Reply #20 on: September 13, 2017, 04:16:19 AM »
Hopefully you have used the board to set up a Quad-LM399-Standalone-Voltage-Reference?

-branadic-
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Offline branadic

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Re: What kind of reference is this??
« Reply #21 on: October 07, 2017, 09:23:10 AM »
I received this unkown reference by Philipp yesterday and had the time to analyse it. If it's a 4x LM399 this is how the circuit looks like.
The +15V and ground are given, as the board is supplied via some prototyp board with a MC7815CT on it.

-branadic-
« Last Edit: October 07, 2017, 09:24:49 AM by branadic »
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Offline Tektron

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Re: What kind of reference is this??
« Reply #22 on: October 07, 2017, 02:31:16 PM »
I received this unkown reference by Philipp yesterday and had the time to analyse it. If it's a 4x LM399 this is how the circuit looks like.
The +15V and ground are given, as the board is supplied via some prototyp board with a MC7815CT on it.

-branadic-
Just opinion, I can be wrong.
If npn type of transistor is correct, then with  +15V at the emitter it will not work. Perhaps collector and emitter must be exchanged?
And connect common point of R(2.7k) and emitter to 4xR(160 Ohm)?
« Last Edit: October 07, 2017, 02:40:37 PM by Tektron »
 

Offline floobydust

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Re: What kind of reference is this??
« Reply #23 on: October 07, 2017, 02:54:02 PM »
In OP's pic, the tabs are rotated 90 degrees, like a two-on-two arrangement for the mystery cans. To me it does not look like a foursome as the pins are not parallel connected?
 

Offline branadic

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Re: What kind of reference is this??
« Reply #24 on: October 07, 2017, 08:03:40 PM »
Quote
Just opinion, I can be wrong.
Just opinion, I can be wrong.
If npn type of transistor is correct, then with  +15V at the emitter it will not work. Perhaps collector and emitter must be exchanged?
And connect common point of R(2.7k) and emitter to 4xR(160 Ohm)?

The BC182B in the circuit is made by ITT, but I wasn't able to find a datasheet from ITT so I took the datasheet from OnSemiconductor. Maybe ITT used a different pinout for the transistor? EBC instead of CBE?
The rest is just as shown as I draw the layout for veryfication.

-branadic-
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