Fullhawking's: Current Rectification

[enigma]

Fullhawking asked: What would i need to rectify 7.5kV 60mA output from a transformer?

Sorry Fullhawking. I tried merging the threads together, and managed to delete the entire thread...

 

[Fullhawking]

That’s okay. I screwed up in the first place, still not sure exactly what I would need though. I know a couple of diodes and I guess some capacitors but as for their rating I am at a loss.

 

[GENIERE]

If the transformer does not have a center-tap on the secondary winding, you can get half wave rectification with a single diode, or use four diodes (bridge circuit) to obtain full wave rectification. If the xformer is center-tapped, you can get full wave rectification with two diodes. A capacitor is not needed except if you want to filter the output. The HV diode that’s used in a microwave oven's magnetron circuit may possibly be available from a local appliance repairer and should exceed your voltage and current requirements. Else try a industrial supplier.

 

[Fullhawking]

Ahh, thank you. As it turns out I have an old microwave ready to be dicected. The diode was HVR-1, when i searched on the internet I found it was rated at 9kv and something like 120ma not 100% sure on that. Would a neon sign transformer be center tapped?

 

[Njorl]

If you want a good DC output, go with a rectifying bridge. You can buy them premade, or make one out of 4 diodes. Also, don't just use capacitors to filter, use an RL circuit. When I built a supply for a free electron laser, I made my own inductors with insulated wire wrapped around pipe.

DANGER - any capacitor you use will build up and retain deadly charges. Build in a drain through a big resistor. Even if you do that, always check the cap to make sure it is discharged before working on the supply.

Njorl

 

[GENIERE]

I've never seen a neon light xformer, but I doubt it would be center-tapped. If a xformer has 5 wires or five tabs it's likely to be, but not for certain, center-tapped.

 

[sheldon]

In order to rectify any ac current use diodes in any of the configurations suggested. As for size of diodes figure the amount of watts per diode needed. For example, a full wave rectifier, divide total watts by 4 and that is the minimum wattage level diode you need, I always overkill a little to make sure they can dissipate the heat if I over load the circuit. 7.5kV 60mA is what your dealing with so that equals 450 watts of total power available. So 112.4 watts per diode. Then at this point you would want to look at diodes at this wattage level and consider their voltage breakdown levels for reverse bias in order to make sure they can handle the 7.5kv. Then power up your photon particle cannon and let it rip. oh your caps, hmmm let's see, ahh yes very large:) look for any cap that has a rating higher than what the rectified DC voltage level will be and depending on how rapid of discharge you need is your farads. If you are designing a pulse gun or rapid fire quasi pulsed phaser you would need a higher farad for rapid recharge, If you are creating a particle beam that needs to sustain long levels of power lower those farads. If you need that current to sustain better add some huge freakin coils and Please I don't want to be on your enemy list after you build all this stuff.

 

[Fullhawking]

Hahahaha. Accually you are very close to what i am building. I hope to use the rectified current to spray charge onto a moving belt for a electrostatic generator of the Van de Graaff type. Another question involving full wave rectification. In a Full Wave Parallel Voltage Multiplier, would the diodes be rated the same or increase with each rung?

 

[wimms]

http://www.voltagemultipliers.com/html/multcircuit.html

Diodes seem to have uniform stress. Caps will get increased volts.