12-09-2021, 06:41 AM
Design of coils is always a compromise. But you've always got a line output transformer so, within reason, you can match any coil to any line output stage.
You can never have too much inductance as such, but the stray C may be too high to give you fast enough flyback. And the resistance may be too high. So for higher scan rates you would tend to design with fewer turns and need more current.
In an ideal world you apply a constant voltage to the scan coils which causes the current to rise linearly. At the end of the forward stroke you switch off the current, resonate the coil with a capacitor which generates a high voltage pulse and causes flyback. Then you turn the switch back on and let the energy stored in the magnetic field flow back into the supply. That's called energy recovery, usually done with an efficicency diode. Of course nothing is ideal so it's all a bit more complicated.
You can never have too much inductance as such, but the stray C may be too high to give you fast enough flyback. And the resistance may be too high. So for higher scan rates you would tend to design with fewer turns and need more current.
In an ideal world you apply a constant voltage to the scan coils which causes the current to rise linearly. At the end of the forward stroke you switch off the current, resonate the coil with a capacitor which generates a high voltage pulse and causes flyback. Then you turn the switch back on and let the energy stored in the magnetic field flow back into the supply. That's called energy recovery, usually done with an efficicency diode. Of course nothing is ideal so it's all a bit more complicated.
www.borinsky.co.uk Jeffrey Borinsky www.becg.tv
