Tone generator and
Audio millivoltmeter

Rörvoltmeter = Vacuum Tube Voltmeter
Sinusvågsgenerator = Sine Wave Generator
This was made from two different articles but I decided to build them into one cabinet.
It is now more than 40 years since I put it together.


The Decade Tone Generator designed by my friend Jon Idestam-Almquist.
From an article in "Radio & Television" April, 1965.


The Vacuum Tube Voltmeter, also designed by Jon Idestam-Almquist
From an article in "Radio & Television" March, 1963.


The voltmeters original appearance...


...and its interior.


Inside my version...


...close-up of the switches with components for frequency selection.


The voltmeter part...


Bottom view with all nice old resistors and capacitors.


The THD is just below 0,1 % (< -60 dB)