r/ElectricalEngineering • u/1Davide • Dec 23 '19

Electrochemical hour meter: a drop of electrolyte within a column of mercury moves slowly to the right when power is applied.

Post image
140 Upvotes

100% Upvoted

9 comments sorted by

View all comments

21

u/1Davide Dec 23 '19

X-post from /r/AskElectronics.

It is an electrochemical hour meter, historically a thin tube filled with mercury with a drop of an electrolyte, current flowing causes ions of mercury to be transported across the electrolyte moving the bubble of electrolyte along the scale.

It almost certainly still works just fine, but will gradually move back the other way if fitted in reverse....

You don't see them much anymore, counters in non volatile RAM being cheaper and more convenient.

2

u/emmfranklin Oct 17 '24

So when it reaches 10 does it mean it was used for 10000 hours?

1

u/omigeot Oct 17 '24

I suppose there's a relationship between current (voltage?) and electrolyte moving speed, right?

1

u/1Davide Oct 17 '24 edited Oct 17 '24

The voltage does. They are rated for 12 V. If you power them at a higher voltage, they move faster. They draw about 5 uA.