I blew the dust & cobwebs off mine to see:

The bezel around the window with the two scales you mentioned was inscribed
"multiply by 100" and "high....low rpm"

The data plate reads as follows:

STROBOSCOPE
stock no. 7 CAD-775000
Mfg. model 510
order no. AF-33(604)7723
S/N 413
110/120 volts 1 phase 60cycle
Electronic Brazing Company
Montclair, N.J.

Sadly the schematic inside was a figment of my imagination.

Lots of equipment, as you already know, was made by more than one company,
so Electronic Brazing may not have been the only manufacturer.

Old Chief Lynn (AKA W7LTQ)

"Henry Kolesnik" wrote in message
...
I just got this black box with no mfg or model #. It's 6.5" wide x 8"
high
x 7.5" deep with a 5.5" reflector for the strobe tube. It has 3 tubes a
6X5,
6N7, and a 1D21/SN4 srtobe tube. A big front knob controls a dial that is
visible on the top with 2 scales on the dial: 6 to 37 and 25 to 145. If
anyone can ID the mfg and model I'd like to see if I can find a schematic.
tnx
hank wd5jfr