DESIGNING A SUPERCAPACITOR CIRCUIT

[magicasd]

hi, i'm given a project assignment of building a supercapacitor which can store roughly 700V to 1000V.
Now i'm designing a circuit (discharging) which can help me light up a few LEDs using Voltage charge stored in the
supercapacitor. The purpose of the circuit is to show that the supercapacitor can Light up the LEDS for a certain period of
time.. I would like to know how to design a circuit which can control the rate of discharge of the supercapacitor.
what are the components required to step down and control the high voltage in order not to destroy the LEDs...

 

[neddie]

High there.
What is the size of the cap. 100nF , 1uF , 100uF ?
100uF at 700V is quite a lot of energy. If you get things wrong , more than your
LED's are going to light up :0) , so be careful!!!
Before I go any further.
I'VE NEVER BUILT OR TESTED THIS CCT , ONLY RUN IT THROUGH A SIMULATOR.
It looks as if it may work , but as I said I've never built it. Simulators can give you misleading results if you don't know what to look for. Everything looks ok though.
The transistor would get hot , dissapating about 4W , but if you are not running it to long it should not be a problem.(use a heatsink if necessary)
It's basically just a pulsed constant current source. It's a LTSpice file/cct so you can sim it and change things if you want. The bjt is a BUV48A ,1000Vce , nothing to special. It's the first model I found , and used.The drive is a 5V, 100KHz, 50% duty square wave , so even a 555 could do it for you.The supply is a 100uF cap , initially charged to 700V , so you can get an idea of how long it will run for. You can see the cap discharging.
Good luck and be careful!!!
Cheers
Rob
P.S If you build this , let me know how things work , or not , as the case may be :0)

 

[PCBWING]

This is a good idea, I know super capacitor is now used in electric vehicles, the purpose is to achieve fast charging. Slow low-power discharge, I would like to see a bright future, thanks for your ideas!