# Electron Gun Power supply

## Main Question or Discussion Point

Hi all, I am making electron gun. I have several High voltage power supply to provide enough voltages to Filament, Anode, Grid, Focus and deflection plates. I want to make electron gun of acclerationg potential of 5-8 KeV. I know I have to give negative supply to cathode or filament. and then put positive voltage to anode plate. But I don't know, the values of voltages that can be given to focus and deflection plate. Is there any method to calculate specific voltages ?

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davenn
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Hi all, I am making electron gun. I have several High voltage power supply to provide enough voltages to Filament, Anode, Grid, Focus and deflection plates. I want to make electron gun of accelerating potential of 5-8 KeV. I know I have to give negative supply to cathode or filament. and then put positive voltage to anode plate. But I don't know, the values of voltages that can be given to focus and deflection plate. Is there any method to calculate specific voltages ?
Hi india
welcome to PF :)

well there's no negative voltage on the filament as such. take a TV CRT tube electron gun for example ... they are usually fed with ~ 12VAC. The Anode at the front end of the tube has anywhere from 20 - 28 kV on it.

why would you try and build one when you could experiment with an old TV/monitor CRT ?

Dave

Thanks Dave, Yes I know, I written wrong. I have 14VAC for filament and 20KV supply for the anode. I have already built gun, just amazed to give power supply for focus electrode and deflection plate. So I want to know, what type of power, and how much power I have to give the focus electrode and deflection plate. is there any relationship between them. or any voltage like 150-200V can be given to deflection plate.

Hi india
welcome to PF :)

well there's no negative voltage on the filament as such. take a TV CRT tube electron gun for example ... they are usually fed with ~ 12VAC. The Anode at the front end of the tube has anywhere from 20 - 28 kV on it.

why would you try and build one when you could experiment with an old TV/monitor CRT ?

Dave