There are two 900 Hz transformers in the clock. The first is the main power transformer running in reverse with an IC power amp feeding 900 Hz sine waves to a 12 volt winding that was originally a secondary for the radar deflection system. Another two windings develop various voltages that are required for the CRT indicator. The former primary develops 100 volts which is fed to the primary of the HV transformer. The main power transformer was the one I had vacuum impregnated and that made only a very minor difference as did rubber mounting it. The HV transformer is potted and there's no practical way to re impregnate it. They are both contributing to the noise which makes it certain to be due to magnetostriction in the cores. The yoke is definitely not the source as the noise is there when the deflection system is not connected. There are no other wound components running at 900 Hz. Interestingly there is an obvious standing wave pattern to the noise, it varies with the observer's ear and head position :-) Noise cancellation is therefore not a practical proposition.
The schematic is large and complex and has parts of the original radar system and parts that I have added as described in my previous posts. I don't have an electronic version. There's also a large AVR program which is still being "improved" as I think of things to add. Morris On Friday, December 19, 2014 2:52:18 AM UTC+11, I wrote: > > I would have thought that the vacuum impregnating of the transformer > would have at least made some difference, even if minor. Is it possible > that it may be something else making the noise, a filter choke in the power > supply, deflection transformers, deflection coils etc.??? Ira. > > > -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send an email to [email protected]. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/aed0649c-4775-433b-91dd-953cfd7a321e%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
