Odd crt

[timmy]

There is a crt on eBay that is from the 1930 s and the pinout is listed but why is there only 2 separate deflection plates but the other 2 seem to be tied to the 2nd anode at least that's what the pinout shows and it only has 8 pins on the end cap so it can't be used for an oscilloscope clock, I would need 10 for it to work.

[WISCOJIM]

Link?

.

[timmy]

Originally Posted by WISCOJIM

Link?

.

eBay under crt tube 1930s clear glass tube

[WISCOJIM]

Thanks.

https://www.ebay.com/itm/Mid-1930s-D...frcectupt=true

[bandersen]

Yes, some early electrostatic CRTs had two deflection plates tied together. You AC couple a signal to the other plate to move the beam back and forth.

[timmy]

So I guess it's out of the question for a scope clock of even tv use. Being both of which need separate plates.

[Tom Albrecht]

One could still make this work. The main thing you need is a potential difference between plates to get deflection (to generate electric field). For each pair, it's OK if one of the two plates is held at a constant potential and the other one is moved relative to it.

This does, however, require twice the voltage swing on that one plate compared to driving opposite plates with opposite waveforms.