TubeTime

Recently I obtained a vintage Clough-Brengle oscillograph. Yes, you read that correctly–the oscillograph is the predecessor of the oscilloscope. Oscillographs lack the trigger function and the calibrated vertical and horizontal scales, along with many other features now ubiquitous on the modern instrument.

First thing I did was pull the cover off to get a look at the innards.

Click the image to jump to the Flickr page which includes some notes describing the various parts of the oscillograph. There’s a lot of rust and grime from years of neglect.

There is more circuitry underneath the instrument, as shown in this photo:

A cluster of components forms the sweep oscillator of the Clough-Brengle oscillograph. The radial-leaded resistors are essentially carbon rods attached to wires and painted with colors indicating their resistance.

Color code for these resistors works as follows: The body color is the most significant digit, the end cap color is the second digit, and the dot on the body is the multiplier. The colors themselves have the same meaning as today.

These resistors are probably of the +/-20% tolerance variety. They are actually trimmed; a single gash in the side indicates where resistive material was removed during production to dial in the value.

For some reason this picture reminds me of a Frank Lloyd Wright building…

I’ll post some more pictures showing the restoration in progress. If you really must look ahead and see them, take a look at my Flickr photostream.