> > <http://threeneurons.files.wordpress.com/2012/11/crt_tstr.gif> > > > > > A lot of the old scope circuits used to run the cathode at a negative > voltage. (this required a well insulated filament transformer.) but > meant that the defection plates were almost at ground potential. >
Yes, If I ever made a real circuit, to use them, I would use the negative cathode voltage approach. But the heater/filament has to be close to the cathode voltage. Less than 100V off. For the simple test circuit, a high positive voltage was just more convenient. Deflection test, is just done by clipping on a test lead, and connecting the individual deflection plates to +1800V or +1400V. It's quick-n-dirty. If you use the negative cathode voltage, then the heater has to have a filament winding that's galvanically isolated from every other supply, except maybe the cathode. The secondary and primary need to have some very good separation, such as a split bobbin transformer. Not a problem back in the old days of analog scopes. They had transformers made just for this purpose. -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. To view this discussion on the web, visit https://groups.google.com/d/msg/neonixie-l/-/if44AVsUKP4J. For more options, visit https://groups.google.com/groups/opt_out.
