Hello Jeffrey and Mike.
The problem I was having is that the flyback pulse was so high, I had visions of it breaking down the winding isolation as it was hitting over 1500 peak to peak as the transformer rang on flayback, it was also going into the line scan time.
Mike it is not frame drive it is line drive for NBTV at 400Hz, sweep at 2.5mS. Flyback is in the order of 0.15 to 0.25 mS I have tried for around 0.23mS, hence trying to wind a bit like an audio transformer? I did say try to.
Anyway here is a picture taken of the scope showing the top trace on the Anode of the EL84 and the lower trace across the scan coil. due to the spikes both traces were at 50 volt per division.
This afternoon I have been playing with what ever diodes I had 1N4007, BYX10 trying to use them as a shunt efficiency diode putting the flyback volts back into the main smoothing cap without a lot of success, it basically clamped the transformer. So I added resistors one across the primary of 2K7 and one across the secondary and scan coils of 680 Ohm, the second resistor made little difference but did a little bit.
So this is now the circuit mod.
I can now show these traces from the scope.
The top trace is still 50 volts per division, but the bottom trace is now 10 volts per division and I am finding that the the voltage trace across the scan coils is swinging negative to positive.
The Buck PSU is running out of current and causing the volts to drop, so I need to get building that mains power supply.
Adrian
The problem I was having is that the flyback pulse was so high, I had visions of it breaking down the winding isolation as it was hitting over 1500 peak to peak as the transformer rang on flayback, it was also going into the line scan time.
Mike it is not frame drive it is line drive for NBTV at 400Hz, sweep at 2.5mS. Flyback is in the order of 0.15 to 0.25 mS I have tried for around 0.23mS, hence trying to wind a bit like an audio transformer? I did say try to.
Anyway here is a picture taken of the scope showing the top trace on the Anode of the EL84 and the lower trace across the scan coil. due to the spikes both traces were at 50 volt per division.
This afternoon I have been playing with what ever diodes I had 1N4007, BYX10 trying to use them as a shunt efficiency diode putting the flyback volts back into the main smoothing cap without a lot of success, it basically clamped the transformer. So I added resistors one across the primary of 2K7 and one across the secondary and scan coils of 680 Ohm, the second resistor made little difference but did a little bit.
So this is now the circuit mod.
I can now show these traces from the scope.
The top trace is still 50 volts per division, but the bottom trace is now 10 volts per division and I am finding that the the voltage trace across the scan coils is swinging negative to positive.
The Buck PSU is running out of current and causing the volts to drop, so I need to get building that mains power supply.
Adrian
Learning as I go!
Youtube EF91 Valve
Youtube EF91 Valve
