Mystery tin resistor box - Page 1
Forum section: electronics / projects

author: enut11
author_rank: Super Contributor
timestamp: May 22, 2020, 10:24:30 pm
content: What is this tin 'resistor' box and what equipment may it have been part of?It has 13 terminals and marked 13071.Size is 9 x 3.5 x 3.5cm

author: enut11
author_rank: Super Contributor
timestamp: May 22, 2020, 10:31:13 pm
content: All the connection points appear to be connected by resistors mainly.Measuring connector-to-connector:1-2 3809 ohms2-3 2999 ohms3-4 short4-5 9 ohms5-6 short6-7 1060 ohms7-8 4062 ohms8-9 1903 ohms9-10 4060 ohms10-11 1132 ohms11-12 75 ohms12-13 75.5 ohms

author: ChristofferB
author_rank: Frequent Contributor
timestamp: May 23, 2020, 10:16:57 am
content: Interesting! Well my first guess would be a resistance standard from some high-end test gear.But that assumes that it litterally IS just a resistance box. Just because there are some measurable resistances doesn't necessarily mean it's only resistors inside.The values seems strange for a meter reference, one would expect a larger range, from milliohms (or short) to multi-megaohms.Can you measure capacitance? It could be RC networks for timing.

author: coromonadalix
author_rank: Super Contributor
timestamp: May 23, 2020, 10:37:52 am
content: Maybe a resistor network for some instrument ... like a frequency generator ?Can you shoot some photos from the bottom, is it completly sealed off ?Stranges values indeed

author: Gyro
author_rank: Super Contributor
timestamp: May 23, 2020, 11:15:26 am
content: You're missing quite a lot of measurements there, you've only measured between adjacent pins. Don't necessarily assume that it is internally wired as just resistors between adjacent pins, you might be measuring combinations. For instance, the pairs reading short might be common connections for a bunch of resistors to other pins. Try a some more probing combinations and the values might suddenly make more sense.Edit: Or 3+4 and 5+6 might be kelvin sensed connections to the 9R resistor.

author: Tom45
author_rank: Frequent Contributor
timestamp: May 23, 2020, 05:09:35 pm
content: Quote from: Gyro on May 23, 2020, 11:15:26 amExactly.There are N*(N-1)/2 measurements (78) but he only did 12 measurements.

author: pardo-bsso
author_rank: Frequent Contributor
timestamp: May 24, 2020, 02:15:10 am
content: Make a hole and peek inside?

author: mikerj
author_rank: Super Contributor
timestamp: May 24, 2020, 09:56:45 am
content: Have you tried measuring between the pins and the case? There looks to be some kind of connection on the side of the case, though it's not clear enough to tell from the photos.

author: Vovk_Z
author_rank: Super Contributor
timestamp: May 24, 2020, 10:40:12 am
content: Quote from: Tom45 on May 23, 2020, 05:09:35 pm/offGood that it isn't N!

author: gbaddeley
author_rank: Regular Contributor
timestamp: May 24, 2020, 01:25:27 pm
content: Could it be a transformer? Resistances seem like taps along a winding.

author: enut11
author_rank: Super Contributor
timestamp: May 24, 2020, 07:49:56 pm
content: Quote from: coromonadalix on May 23, 2020, 10:37:52 amIt is completely sealed.More resistance checks, this time referenced to pin #1.2: 3809 ohms3: 809 ohms4: 809 ohms5: 804 ohms6: 804 ohms7: 521 ohms8: 3810 ohms9: 3808 ohms10: 521 ohms11: 877 ohms12: 806 ohms13: 877 ohmsNone are connected to the metal can.

author: ratio
author_rank: Regular Contributor
timestamp: May 24, 2020, 10:47:57 pm
content: Draw a picture looking down from above, measure the resistance between all of the terminals that had wires connected, & show them on the pic.Also, do you have a CLR meter of some kind?

author: enut11
author_rank: Super Contributor
timestamp: May 25, 2020, 05:41:44 am
content: I have a simple CR/Trans tester.The picture below shows the resistances that I measured between the previously soldered terminals. This is part 1 as interaction between upper and lower rows is not shown here but will be in a follow-up.

author: enut11
author_rank: Super Contributor
timestamp: May 25, 2020, 07:40:43 am
content: This is the second part - Resistance measurements between the upper and lower rows.Actually, I am not sure if these diagrams help. Just a rats-nest of resistances.

author: Ian.M
author_rank: Super Contributor
timestamp: May 25, 2020, 08:13:21 am
content: Don't do a diagram, do a spreadsheet. Terminal numbers as (text) column headers and row values, then a grid of measurements at each row/column intersection. Obviously the diagonal where row=column will be blank. Enter shorts as 0 and leave opens blank.Always put the positive probe on the row label terminal so the results will meaningfully show the presence of any diode junctions, i.e if resistance(col,row)<>resistance(row,col)Also, *HOW* is the box sealed? some good photos of the sides may lead to suggestions for opening it non-destructively.What does it weigh, and what are its dimensions?What does it sound like if you tap it with a hard object? e.g. does it click, clank or ring.Estimate where its center of gravity (C.G.) is by rolling it across a round toothpick, and marking the position of the toothpick when it tips. Do this in both directions across a long side, and both directions across the base.If its heavy and the C.G. is fairly central, perhaps biased a bit towards the base, it would make gbaddeley's transformer suggestion more likely.

author: enut11
author_rank: Super Contributor
timestamp: May 25, 2020, 09:25:11 pm
content: @Ian.MThe sketches were uploaded due to a query from another member and they do help somewhat. I will also look into your spreadsheet idea.Some more pix attached showing the box is solder-sealed.Box weighs 97g and size is 9 x 3.5 x 3.5cmNoise? sounds like a clickCG is approx central on all planes.There are no diodes in the box

author: Gyro
author_rank: Super Contributor
timestamp: May 25, 2020, 09:35:15 pm
content: It looks as if that box has already been opened - there is no continuous solder fillet (unless it is just the photo angle), maybe just tack-soldered in a few places.

author: Ian.M
author_rank: Super Contributor
timestamp: May 25, 2020, 09:54:10 pm
content: The weight means its unlikely to contain a transformer or to be potted.As Gyro points out, that looks like it could be desoldered reasonably easily using a high enough wattage soldering iron. Remove as much solder as possible using solder-wick, then work round it prying the joint open slightly while heating it, so residual solder doesn't bridge across the joint. It will probably remain in contact at the corners so you'll have to clamp it in a vice and work round reheating them and prying between the top of the vice jaws and the edge of the lid to gain a small movement at each corner in turn till the lid comes off.Opening it will probably be less tedious than taking a full matrix of measurements (aka: the spreadsheet), and you'll also gain a reusable screening box, and if you are lucky some precision resistors.

author: M4trix
author_rank: Frequent Contributor
timestamp: May 25, 2020, 10:20:29 pm
content: Well, you could end the debate by grabbing a hacksaw and....

author: Ian.M
author_rank: Super Contributor
timestamp: May 25, 2020, 10:49:18 pm
content: I would only take a hacksaw to it as a last resort as the enclosure is probably of greater use than the contents. If its too difficult to get the lid off by ordinary desoldering, it would be less destructive to slit the corners of the lid with a Dremel cutting disk so the lid sides can be bent out slightly to ease desoldering them. It could still be reconstructed if anyone has need of it, with the corner slits filled with solder, wiped to original profile.

author: enut11
author_rank: Super Contributor
timestamp: May 26, 2020, 12:16:40 am
content: Quote from: Gyro on May 25, 2020, 09:35:15 pmNope, there is continuous solder around the lid with no evidence of tampering

author: bob91343
author_rank: Super Contributor
timestamp: May 26, 2020, 04:08:30 am
content: I would try my hot air desoldering station on small areas. I have opened boxes like this by heating with a big iron and forcing a screwdriver into the solder. Once you get purchase you can try to bend it, as the solder is softer than the can.

author: exe
author_rank: Unknown
timestamp: May 26, 2020, 08:00:55 am
content: Drill a hole and use a borescope

author: enut11
author_rank: Super Contributor
timestamp: May 27, 2020, 12:58:07 am
content: That would be too easy. Where is the challenge?

author: bdunham7
author_rank: Super Contributor
timestamp: May 27, 2020, 01:17:57 am
content: Can you measure 11-13 and 7-10? And maybe 2-8 and 2-9?

author: gbaddeley
author_rank: Regular Contributor
timestamp: May 27, 2020, 11:46:04 am
content: Either do the spreadsheet, or provide a list of pins (combine 3&4 and combine 5&6, as they are shorted), and find the 2 other pins that have LOWEST resistance to the pin in question, and provide those 2 resistances.Your rats nest measurements so far are not easily decoded.

author: alanb
author_rank: Frequent Contributor
timestamp: May 27, 2020, 01:31:57 pm
content: Why not feed in some low voltage AC between a couple of the terminals and measure the voltage on others to see if it is a transformer? Input between 1 and 5 and measure 7 - 12.

author: Labrat101
author_rank: Unknown
timestamp: May 27, 2020, 04:33:13 pm
content: My first question is where did you find it??was it from an old Building?I think you are going to find a load of hand wound chokes inside . wound on bobbins.So be careful how much heat you apply as it will melt the wax coated coils .Measure the Henry not resistance ..It is , Was a custom part. The tin should give you a clue .. Its a Medical box . syringe box from early 1930..

author: enut11
author_rank: Super Contributor
timestamp: May 28, 2020, 01:55:25 am
content: Quote from: bdunham7 on May 27, 2020, 01:17:57 am11 to 13 is 0 ohms7 to 10 is 0 ohms2 to 8 is 1 ohm2 to 9 is 1 ohm

author: gbaddeley
author_rank: Regular Contributor
timestamp: May 28, 2020, 08:00:56 am
content: Another guess is that it’s a resistive attenuator network, possibly balanced, possibly 75, 150, 600 Ohm or some other multiple.

author: enut11
author_rank: Super Contributor
timestamp: May 28, 2020, 09:05:36 am
content: Quote from: Labrat101 on May 27, 2020, 04:33:13 pmI acquired it along with a lot of other bits and pieces and do not know the origin. No intention of breaking into it at this time.

author: Labrat101
author_rank: Unknown
timestamp: May 28, 2020, 11:54:48 am
content: From the pin set out they are groupedThere is a space between the 2 groups2 on top 4 on bottom. Pins 1 & 2 (3) 6,7,8,9 Block 2# 3 (4) (5) to 10,11,12Pins 1,2,3 & 5 have been connected solder used... bottom bank 7,8,9, -- 11,12also 13 071 collates to the pins maybe a red herring.This to me looks like the layout for controlledOscillator. Input at top and frequency are at theBottom . There well could be an old type cat's hair Crystal's OA81 and coils .They will give these odd measurement . I think it's an old receiver home made. The 2 bottom pins with zero are the ground and plain or Arial . With a cap isolated. .Make measurements with a signal gen start low 230hz on the to top measure at lower blockThe number on the top is the wave length.Your drawing did not make sense as all resistance. The low values are probably coils And the cap are not showing nor are the oscillators...Also the box is hermetically sealed for a good reason . other wise it would have been screwed down.There maybe an Old Vacuum tube that would also account for the light weight the post war tubes were inMetal cans . 90v grid 6.3v heater. if it is an oscillator tube it will have a low heater voltage .Have not see one for over 50++ yearsYou will have to use all your resources. on this one . But its Not a resistance Box .But solve 1 block, first left top and the bottom 4 .

author: lowimpedance
author_rank: Super Contributor
timestamp: June 02, 2020, 03:23:25 am
content: Okay the mystery tin box could very well be an 'esi ' custom resistor enclosure for a specialist application, see picture. Same pin count, although a slight difference in pin arrangement.The only way to truly know is to crack out the dremel !.(sorry about the pic quality but the original was poor to start).

author: Labrat101
author_rank: Unknown
timestamp: June 02, 2020, 12:37:14 pm
content: Quote from: lowimpedance on June 02, 2020, 03:23:25 amWell Done .. Its A ESIAC and can do advanced Algebraic ComputingAnd has gone though special Ageing process . Put a scope on it and see if its still 2ppmThe X, Y, & Z are the 3 top pins .Do you have a scope with 3 axis ..? you need an analogue ScopeIt maybe still under warrantyHave Fun it should give a nice output .PS Don't crack it open .. you will kill the old shellac that they use to use .

author: lowimpedance
author_rank: Super Contributor
timestamp: June 02, 2020, 11:01:28 pm
content: Are you taking the piss??.Did you supply the unit in question to enutt11 ??........ no you did not. Clearlyyoudon't know its origin !.What makes you so sure its what you say it is, cough up some proof rather than dismiss mine.Here's a tip its not from the 1930's ok !.

author: babysitter
author_rank: Frequent Contributor
timestamp: June 03, 2020, 07:09:29 am
content: Time for a visit to the dentist. And his great x-ray device! Don't for get a box of coffe for his employees.

author: Labrat101
author_rank: Unknown
timestamp: June 03, 2020, 08:15:14 am
content: Quote from: lowimpedance on June 02, 2020, 11:01:28 pmTo whom are you quoting to ?I never said you were wrong .. Maybe the year is incorrect 1950 - 60s.I have see one of these before. It was in my father's lab . 60 years ago .I was only about 7 . It sat on the bench next to a big ass Tube scope CRT .What and how it was used for was just making funny patterns .. .. you think at 7yrsI knew what an algebraic wave form was or for ..So I remember it was something to do with wave forms ..60+ years is a long time. To forget. .(Father was a physicist made all sorts of weird stuff) ..Have fun life is to short ..