Wheatstone bridge

[SeanB]

Thought I would share a few pics of my Wheatstone bridge.

Front panel.


Wheatstone bridge by SeanB_ZA, on Flickr

Shortform instructions inside the lid.


Inside front cover by SeanB_ZA, on Flickr

Back cover removed, all metal screws into nice brass posts.


Inside view by SeanB_ZA, on Flickr

Meter movement back with it's wirewound hand made resistors.


Back of meter by SeanB_ZA, on Flickr

Range resistors, they look like bamboo sticks.


Range switch by SeanB_ZA, on Flickr

Side view of the switch.


Switch details by SeanB_ZA, on Flickr

Galvonometer showing the offset due to the shorting link.


Galvanometer by SeanB_ZA, on Flickr

Hard to get a lower resistance shorting link than this copper foil across the inputs.


Close to zero by SeanB_ZA, on Flickr

All running off 4.5V from 3 cells. The original D cells it had in it when i got it had leaked a little, and I did not have any to hand when I had finished cleaning up the holder and so I used 3 C cells and some metal spacers ( actually some vibration mounts) to fill the gap, along with some cardboard to fill the sides. Works well enough, and the cells are a lot cheaper to buy, and last just as long.


batterybodge by SeanB_ZA, on Flickr

[MJLorton]

What a gem! I had not heard of Yokogawa before I came across a clamp meter of theirs I really want for review:

Yokogawa (CW10): http://tmi.yokogawa.com/products/portable-and-bench-instruments/portable-power-monitorrecorder/model-cw10-clamp-on-power-meter/

[Mr Eastwood]

Very neat inside and out!   the blobs of solder on the "bamboo" range resistors, I guess they were for fine adjustment?

[SeanB]

Those are to solder on the leadout wires, as nichrome or manganin resistance wire is both very fine and a pain to solder, so it is likely this is a silver loaded solder to attach the copper leadout wires reliably.

I had a lot of roach droppings inside and out, and the case has been nibbled a bit by rats, though luckily only the leather strap and outer case had bites Took a week to clean it with a cloth and bag it with roach spray to kill those inside, and remove the egg cases.

[Paul Collins M0BSW]

Brilliant , see how could anyone not want to own a piece of equipment this like, far better than all this soft touch backlit stuff, which I doubt would last the test of time, and I would bet this one would still be there doing its job well. Your duty bound to look after and use this piece of wonderful history.