discharging the capacitor

Hi !
Hardware: 10mF ~ 50V capacitor BU2508 (Silicon Diffused Power Transistor) 100K , 16K resistors
This is project goal:
I dont need to charge the capacitor to 50V so i want to make discharge when the capacitor reach 30V. The discharge will go thru transistor and then to some other elements.
** I just need to trigger this capacitor discharge on some predefined voltage level ( 30V ) and thats it. How to make this ? **
Joja
p.s. i can not change the capacitor but i can change the transistor ( if this is necessery ).
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Joja wrote:

try a zener diode and a SCR
hint: search around for "crowbar circuit"
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I did take a look on the google and i found this: http://www.kbt-dc-supplies.com/crowbar.php
OK. Becuse my transistor is connected to transformer i can make something like this : ?
DC source --> crowbar --> BU transistor --> transformer
Do you have other suggestion ?
*****************************************

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Joja wrote:

it would help if you stated what you need to accomplish. my guess so far would be some type of strobe light circuit.
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You are not far from the main idea :-). The point is that i need to be sure that the capasitor is discharged on some voltage level and that the rest of the voltage will be passed to transistor . So i need this situation:
capasitor will be charged to 50V ( or some other value ) crowbar will trigger this on some 25 volts 25 Volts will be transfered to BU transistor and from there to transfomer ( or some tesla coil ( this part is in development ))
Joja ******************************************* my guess so far would be some type of strobe light circuit.
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You want a capacitor with a voltage rating of twice what your max working voltage is expected to be.
You need to give more information. Pulse rate. charge discharge cycle rate.
You want to bone up on Usenet, this forum you are invading, and learn how to refrain from top posting.
http://tools.ietf.org/html/rfc1855
http://www.caliburn.nl/topposting.html
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Perfect voltage range for a diac too, either to trigger an SCR, or possibly just by itself.
--
Andrew Gabriel

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