01-11-2021, 05:26 PM
(This post was last modified: 01-11-2021, 05:27 PM by ppppenguin.)
The high peak voltage is the inductance of the coil resonating with stray capacitance. So you can reduce the peak by adding capacitance across the coil. You will also slow down the flyback. V = L * dI/dt can't be circumvented. If you want fast flyback you'll get a lot of volts.
Even in a field timebase, where the resistance of the coil is dominant, you'll still get a flyback peak. The images are taken from my final year uni project in 1978. The main image shows a field timebase as a block diagram. The feedback is taken from a current sense resistor to ensure very linear scan. You can see the negative flyback peak in the enlarged image. It was limited by the -15V negative voltage rail of the timebase. This also set the speed of the flyback. In fact the feedback loop is momentarily opened during flyback as the amplifier saturates but it recovers very quickly.
Even in a field timebase, where the resistance of the coil is dominant, you'll still get a flyback peak. The images are taken from my final year uni project in 1978. The main image shows a field timebase as a block diagram. The feedback is taken from a current sense resistor to ensure very linear scan. You can see the negative flyback peak in the enlarged image. It was limited by the -15V negative voltage rail of the timebase. This also set the speed of the flyback. In fact the feedback loop is momentarily opened during flyback as the amplifier saturates but it recovers very quickly.
www.borinsky.co.uk Jeffrey Borinsky www.becg.tv
