Dynamco DM2022S Digital meter review and teardown

[mace1337]

What valves are those? They look like Mullard EF37's or something.

[triden55]

In North America all switches UP=ON

[douro20]

Non-Linear Systems used to make an autoranging digital voltmeter (the first in the world) which used relays and Strowger selectors sealed in cans filled with transformer oil. No transistors or vacuum tubes- just all electromechanical logic.

[zaprodk]

Wow. That wiring is just beautiful!!!

[AntiProtonBoy]

Awesome instrument! Love vintage gear.

[CampKohler]

"The collection of all Muirhead`s electrical instruments from the Elmers End electrical works was acquired by the Science Museum in 1989." Do you suppose they have a DM2022 in the collection? You could give them a call and see.

[CampKohler]

"Down" on the power switch is "on"? It must have been made for the Australian market, where, of course, everything is upsidedown. :-)

You can read about the company at .muirheadaerospace dot seeohem/our-company/history dot html

[mikeselectricstuff]

@CampKohler Huh? "down=on" is the normal convention in the majority of switches I've seen, except circuit breakers where there are failsafe considerations.

[CampKohler]

@mikeselectricstuff What? What? Go to Google, click Images and search "switch on" or "switch off" and look at the pictures, many with labelled positions. How many do you see where up is off or 0 vs. how many where up is on or 1? (One pix shows a knife switch the wrong way, but that you definitely want to have up = on, because gravity should turn it off if things don't grip right.)

Of course, for the ultimate, final authority, search "switch" on Wikipedia and see the pix. :-)

[CampKohler]

@mikeselectricstuff For one more bit of evidence, search "ignition switch panel" and click wiringproducts dot c o m. The pix shows a red plastic safety cover typically used on toggle switches to arm nuclear weapons, etc. In case of accidental activation, by say a bump, it is designed to move the toggle lever downward to the off (or non-city-destroying) position. This could be muddled up only by using a double-throw switch mounted UPSIDE DOWN WITH THE WIRING REVERSED. I rest my case.

[mikeselectricstuff]

@CampKohler Every single switched outlet in the UK, which, as everyone knows, has the best electrical system in the world, uses down as on. Case closed.

[Kankki1]

@mikeselectricstuff No way man. You sarcastic about the UK having the best electrical system right ;)

Up = On

Anything else feels wrong.

[ib9rt]

@Kankki1 The strange "up = on" convention is one of the many odd things you have to get used to when you first arrive in America. Down = on is normal everywhere else.

[Kankki1]

@ib9rt I'm from Finland. All of the countries in scandinavia have Up = On

[lennyhome]

Beauty! I like it. Thumbs up!