The Museum of T&M Instruments

BRIEF SPECS

Vertical	2 mV/div to 50 V/div
Time Base	0.5 us/div to 0.5 s/div
Power	5 W
Dimensions	9 cm x 9 cm x 9 cm & 9 cm x 9 cm x 18.5cm
Weight	1 kg
Technology	tube
Price	unknown

This scope was made for education purposes only. The circuit is broken into two submodules: the indicator ("Sichtgeraet") and the sawtooth-generator ("Kippgeraet"). Of course there was no real attempt to make this an calibrated instrument. It's just as simple as possible to show the basic idea behind the oscilloscope.
Because it was used in schools, the thing is powered with 6.3 VAC only. The indicator is powered with 42 VAC from the sawtooth-generator. The tubes are one DH3-91 (1CP31) and one PL21 (2D21). I reverse-engineered the circuit which you can found here:

Sichtgeraet 9400 schematics (94k)

Kippgeraet 9401 schematics (97k)