Quote:
Originally Posted by AlanInSitges
This is such an awesome project! I have often thought it would be cool to do something similar...Here's hoping this really takes off.
...
|
I totally agree!
Regarding output amplifier type:
The horizontal sweep is operating a load that is mostly inductive at horizontal frequency. This is because of the number of windings needed to create a magnetic field to deflect the beam. This dictates that the output circuit apply a constant voltage to the yoke during sweep, so the output ends up just switching on and off. This is convenient because it reduces the power handling requirements (wasted energy) tremendously. The horizontal output device has to conduct for a bit more than the right half of the sweep (to make up for resistive losses) but most of the energy is stored in the magnetic field and transferred to the resonant flyback capacitor and then to the damper diode to make the left half of the sweep.
In both tube and transistor horizontal outputs, you want the switch-off to be as fast as possible, to prevent having both current and rising retrace pulse voltage present simultaneously. In tubes, it's a matter of total power dissipation, and in transistors it's much more critical because the safe operating area (limit of simultaneous voltage and current) is very small. A bad design will kill an output transistor on the first retrace, before you can even figure out what happened.
The vertical output amplifier is much closer to linear, modified somewhat, because at vertical frequency the yoke is mainly resistive but partly inductive. So, it already operates mainly as you proposed.
Electrostatically deflected tubes use linear drive waveforms with incidental power losses in the amplifier but none in the deflection plates.