01-27-2017, 05:59 PM
As far as I know there are three different models. I know I seem like a know it all but maybe more. Early style has a square box at the back end of the sm. Inside there's a vertically mounted electromagnet. Under it there is a small thin permanent magnet use to center the vane.
Next model has the spring in the center to center the vane and has a smaller horizontal mounted electromagnet. I'd guess that thse were used around 1935-36. These seem to have a lower resistance than the others around 500-900 ohm where the older one are closer to 1.5K
The later models 37 &38 have a round permanent magnet held in by a snap ring and the electromagnet is around a metal tube that supports the vane.
Next model has the spring in the center to center the vane and has a smaller horizontal mounted electromagnet. I'd guess that thse were used around 1935-36. These seem to have a lower resistance than the others around 500-900 ohm where the older one are closer to 1.5K
The later models 37 &38 have a round permanent magnet held in by a snap ring and the electromagnet is around a metal tube that supports the vane.
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got it!
Terry
![[-]](https://philcoradio.com/phorum/images/bootbb/collapse.png "[-]")
