this is a very cool Hewlett Packard RMS voltmeter, its fundamental design sounds quite simple, but its implementation is as always out of this world, released in 1964 and end in 1980 this one works really good, I managed to fine adjust it for best possible readout.
See also my HP 400E AC rms voltmeter video :    • HP 400E AC rms Voltmeter 1969 test te...  

#teardown
#hewlettpackard
#vintage

I use auto generated subs, I go thru them my self, but i am far from perfect at finding all errors, so if you find errors worth fixing, please comment (or PM) with the TIME in the video you saw the error, i will be happy to fix it. This also apply to the Danish version.

(Thanks to all my Sponsors / Traders / Swappers / Sellers / Buyers, without your support and constant flow of cool items in/out, none of this would be possible)