That is a "chopper" basically a high speed relay mechanically tuned to operate with mimimum contact bounce, normally at a specfic frequency. They were replaced by neons and resistive photo cells, FETs and then IC's
Google "chopper Amplifier"
Robert G8RPI
From: Joseph Gray jgray@zianet.com
To: Discussion of precise voltage measurement volt-nuts@febo.com
Sent: Friday, 9 August 2013, 4:44
Subject: [volt-nuts] Cool looking old stuff
I'm helping the local surplus guy by going through some old gear and
checking it over. Sometimes I find something useful :-)
I just took apart a Millivac Instruments MV-37B DC Differential Voltmeter,
mostly because I was curious to see what was inside (I haven't powered it
on yet). Most of what I saw was not very impressive, but one item stood
out. Take a look at the two pictures.
https://dl.dropboxusercontent.com/u/19599147/Millivac%20-%20Rear.jpg
https://dl.dropboxusercontent.com/u/19599147/Millivac%20-%20Closeup.jpg
Joe Gray
W5JG
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
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That is a "chopper" basically a high speed relay mechanically tuned to operate with mimimum contact bounce, normally at a specfic frequency. They were replaced by neons and resistive photo cells, FETs and then IC's
Google "chopper Amplifier"
Robert G8RPI
________________________________
From: Joseph Gray <jgray@zianet.com>
To: Discussion of precise voltage measurement <volt-nuts@febo.com>
Sent: Friday, 9 August 2013, 4:44
Subject: [volt-nuts] Cool looking old stuff
I'm helping the local surplus guy by going through some old gear and
checking it over. Sometimes I find something useful :-)
I just took apart a Millivac Instruments MV-37B DC Differential Voltmeter,
mostly because I was curious to see what was inside (I haven't powered it
on yet). Most of what I saw was not very impressive, but one item stood
out. Take a look at the two pictures.
https://dl.dropboxusercontent.com/u/19599147/Millivac%20-%20Rear.jpg
https://dl.dropboxusercontent.com/u/19599147/Millivac%20-%20Closeup.jpg
Joe Gray
W5JG
_______________________________________________
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.
