Latest Acquisition and it's mint.

[telectrix]

H.W,Sullivan, type of Wheatstone Bridge . Son found it on faceache or some other anti-social gossip site. £15. Guess it's age to be about 80 -90 years. Lucien would have been able to give me some info., like what voltage battery etc, but any info appreciated.

Google tells me that the company was founder in 1897 , manufacturing telegraph machines.
.,

 

[snowhead]

Looks like the meter has been "upgraded" on yours Tel,

V126 4.5v battery from the link below, unless your has been modded for 4 x "C" cell as pic below.

John's Virtual Museum - Decade Bridge 43379

This is a 4-decade Wheatstone bridge with ranges from 10 ohm to 10 megohm full-scale. The unit has been modified at some time to take four "C" cells instead of the original 4.5 V 126 battery. Intriguingly, it suggests that a 225 V battery is required for the 10 megohm range. The detector isn't

sites.google.com

A6570 (Ever Ready No. 126 replacement) 4.5V 'Box Battery' (A6570, Hercules HS6570G, 3LR12, 3LR20, 126) 4.5V Box Battery.

 

[telectrix]

Looks like the meter has been "upgraded" on yours Tel,

V126 4.5v battery from the link below, unless your has been modded for 4 x "C" cell as pic below.

John's Virtual Museum - Decade Bridge 43379

This is a 4-decade Wheatstone bridge with ranges from 10 ohm to 10 megohm full-scale. The unit has been modified at some time to take four "C" cells instead of the original 4.5 V 126 battery. Intriguingly, it suggests that a 225 V battery is required for the 10 megohm range. The detector isn't

sites.google.com

A6570 (Ever Ready No. 126 replacement) 4.5V 'Box Battery' (A6570, Hercules HS6570G, 3LR12, 3LR20, 126) 4.5V Box Battery.

View attachment 109312

only problem is it's listed as "out of stock".

 

[snowhead]

only problem is it's listed as "out of stock".

It was just an example.
I thought you'd go for the budget option of converting to 3 x C (not 4 as I put earlier)

 

[telectrix]

ordered a 4.5V flat bugger , like wtah you had in a bicycle front lamp in the 60's,if we ever bothered with lights back then.no lights on bike made it harder for the bizzies to find us.

 

[timhoward]

Very nice!
As you probably gathered it can measure resistances very accurately. Usually as accurately if not more accurately than a modern MFT. It can also do Murray loop tests to predict where a fault is.

Basically if a cable is faulting to earth, you join the conductors at the far end and measure the resistance as usual.
Then you'd switch to "Murray Loop", and the negative battery terminal would presumably need connecting to a good earth.
You'd then measure again. From these two values, and the formula in the manual, the distance along the line that the fault is can be calculated.

A Megger BR4 manual (which I found online as I have one) would fill in some of the blanks about the concepts.

 

[telectrix]

fitted a 4.5V battery. sadly, no matter what I do with dials and switches, there's no response from the galvanometer: stuck on 0. it's not locked as the zero adjust moves the needle. going to open the box and see if there's anything glaring,

 

[timhoward]

fitted a 4.5V battery. sadly, no matter what I do with dials and switches, there's no response from the galvanometer: stuck on 0. it's not locked as the zero adjust moves the needle. going to open the box and see if there's anything glaring,

The most likely is that the galvanometer has become damaged.
As it's removable you could try testing it directly by cooking up something like this.

Make resistors P, Q, and R the same and S about half the value. It should move.
Or just stick an AA battery across it!

 

[timhoward]

PS, if anyone else wants to join the bridge tester party, there's another similar one here:

Vintage Galvanometer L&N Leeds & Northrup Type S Test Set No. 5300 in Case | eBay

Find many great new & used options and get the best deals for Vintage Galvanometer L&N Leeds & Northrup Type S Test Set No. 5300 in Case at the best online prices at eBay! Free delivery for many products.

www.ebay.co.uk

 

[DPG]

PS, if anyone else wants to join the bridge tester party, there's another similar one here:

Vintage Galvanometer L&N Leeds & Northrup Type S Test Set No. 5300 in Case | eBay

Find many great new & used options and get the best deals for Vintage Galvanometer L&N Leeds & Northrup Type S Test Set No. 5300 in Case at the best online prices at eBay! Free delivery for many products.

www.ebay.co.uk

Nice example that.

 

[telectrix]

The most likely is that the galvanometer has become damaged.
As it's removable you could try testing it directly by cooking up something like this.

View attachment 109363

Make resistors P, Q, and R the same and S about half the value. It should move.
Or just stick an AA battery across it!

going to open it up tomorrow - see what's what. will gry above first option.

 

[RDB85]

H.W,Sullivan, type of Wheatstone Bridge . Son found it on faceache or some other anti-social gossip site. £15. Guess it's age to be about 80 -90 years. Lucien would have been able to give me some info., like what voltage battery etc, but any info appreciated.

Google tells me that the company was founder in 1897 , manufacturing telegraph machines.
.,

A bargain indeed if the below is anything to go by:

Vintage H. W. Sullivan Decade Bridge tester, type 43379 wooden box | eBay

Find many great new & used options and get the best deals for Vintage H. W. Sullivan Decade Bridge tester, type 43379 wooden box at the best online prices at eBay! Free delivery for many products.

www.ebay.co.uk

 

[telectrix]

A bargain indeed if the below is anything to go by:

Vintage H. W. Sullivan Decade Bridge tester, type 43379 wooden box | eBay

Find many great new & used options and get the best deals for Vintage H. W. Sullivan Decade Bridge tester, type 43379 wooden box at the best online prices at eBay! Free delivery for many products.

www.ebay.co.uk

that is identical to mine. same model number. 43379.

 

[telectrix]

update.. opened it up and found this. galvo has deffo been updated as it has a PCB and on it there's a 8 legged microchip. there's 2 sets if leads coming off ending in 2 PP£ connectors, but no connection to the internals of the machine, and no apparent place for them to go. pointless fitting PP3/s as would just be a stand alone galvanometer . Any ideas???

 

[telectrix]

further investigation finds that the 2 securing release pillars for the galvo are actually terminals, connected to both the galvo and the internal resistor banks. tomorrow will try and see if connecting 2 PP3s will get some life into it. if i read it right, maybe someone has modded it to use PP3s instead of the original battery, necessitating the removal of the meter to replace said batteries. weird.

 

[timhoward]

further investigation finds that the 2 securing release pillars for the galvo are actually terminals, connected to both the galvo and the internal resistor banks. tomorrow will try and see if connecting 2 PP3s will get some life into it. if i read it right, maybe someone has modded it to use PP3s instead of the original battery, necessitating the removal of the meter to replace said batteries. weird.

What you are trying to reinstate is along these lines:

Hopefully that will set your bearings. (EDIT The middle button should say G and the bottom button should say B, sorry)

For testing purposes you could swap out the Galvanometer with a digital multimeter.

Here it is working....observe that with the DECADE set to 678 ohms, and a resistance of 678 ohms between X1 and X2 we get 0v in the middle:

For academic interest only, see this old thread of mine - it's exactly the same concept but yours is ready to roll, wheras a post office box needs a power source and a galvonometer/voltmeter connecting up.

Post Office Box experiment - in - Electrical Engineering Chat

, Post Office Box experiment, Electrical Engineering Chat, ElectriciansForums.net Est.2006 | Free Electrical Advice Forum and page_number.

www.electriciansforums.net

 

[telectrix]

RESULT.....Connected 2 x PP3 batteries to the galvo and got deflection. then added the 4.5V battery in the original position in the cabinet lid. a (nominal) 10K resistor then connected to X! and X2. Dials operated to give an almost Zero reading on the galvo, ( 1 division from absolute 0 ) and the setting showed 9.6K. Will try several different resistor values later. I have an organiser full of them, from 0.1 ohms to 10 Megohms.
The PP3s must be a requirement of the updated galvo.

 

[xmetal]

The original picture looks similar to the PO ohmmeter 18a 'megger'. That used a 9v battery.

 

[timhoward]

The original picture looks similar to the PO ohmmeter 18a 'megger'. That used a 9v battery.

I know what you mean. The 18A is a beautiful machine. British Racing Green....
Very similar in function, it has an additional ingenious trick to help engineers find a broken (as opposed to shorted) cable location. You join broken to good at far end, plug headphones in, find a quiet spot and run some maths.

The 'upgrade' (still sold today) isn't quite as aesthetically pleasing....

Any collector of electrical junk should keep an eye on "GPO Tester" results on ebay. There's even a brand new complete 18C for £50 at the moment. (but my wife said "No" and I have enough bridge-based testers!)

 

[DPG]

I know what you mean. The 18A is a beautiful machine. British Racing Green....
Very similar in function, it has an additional ingenious trick to help engineers find a broken (as opposed to shorted) cable location. You join broken to good at far end, plug headphones in, find a quiet spot and run some maths.


View attachment 109477

The 'upgrade' (still sold today) isn't quite as aesthetically pleasing....

View attachment 109478

Any collector of electrical junk should keep an eye on "GPO Tester" results on ebay. There's even a brand new complete 18C for £50 at the moment. (but my wife said "No" and I have enough bridge-based testers!)

That green one is very nice. Is it a military spec one?