Capacitor Charger Circuit

Thread Starter

Mark34

Joined Sep 23, 2016
24
I want to modify the capacitor charger circuit and use a 4-pin step-up transformer, can someone show me how to modify the circuit and still charge the capacitor. (circuit image attached)
Best.png
 

MisterBill2

Joined Jan 23, 2018
11,643
In addition to missing all of the component values you are showing a circuit with 5 connections to the transformer. Besides that, we have no description at all of the transformer that you want to use.
Is this the circuit of a device that you already have? Or a circuit that you want to build using a transformer that you have?How much voltage do you want to charge the capacitor up to? And how fast?
 

Thread Starter

Mark34

Joined Sep 23, 2016
24
I need a general idea like the circuit image attached but with a 4 pin step-up transformer, it will be a 400V capacitor to be charged in max 1 minute.
 

LesJones

Joined Jan 8, 2017
3,702
The flash driver from a disposable film camera may be a good source of a step up inverter. It will probably not give 400 volts as it is but you might be able to modify the rectification to a voltage doubler.

Les.
 

Papabravo

Joined Feb 24, 2006
18,153
Transformers are AC devices and may or may not do anything interesting with the circuit you have.

EDIT: It will charge the capacitor exactly one time. If there is a path to ground the capacitor will discharge to about one diode drop below the battery voltage. The diode is a Schottky so figure 0.2 to 0.4 Volts.

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Thread Starter

Mark34

Joined Sep 23, 2016
24
That is not correct, because there is no way for the capacitor to discharge. See the simulation I added to post #2.
Thanks, capacitor discharge is not a problem I will have switches to disconnect the capacitor and connect it to some other circuit.
 

Papabravo

Joined Feb 24, 2006
18,153
Thanks, capacitor discharge is not a problem I will have switches to disconnect the capacitor and connect it to some other circuit.
It still won't oscillate as you have drawn it and the transistor is never really turned on for any purpose at any time that I can see. You might want to consult your sources to see where you went wrong.
 

Thread Starter

Mark34

Joined Sep 23, 2016
24
It still won't oscillate as you have drawn it and the transistor is never really turned on for any purpose at any time that I can see. You might want to consult your sources to see where you went wrong.
I don't understand, it's the same circuit why mine does not work ? what's that vcap connection ? where does it go ?
 

Papabravo

Joined Feb 24, 2006
18,153
I don't understand, it's the same circuit why mine does not work ? what's that vcap connection ? where does it go ?
"vcap" is just a label on that particular net; it is used for plotting the voltage on the capacitor. It does not go anywhere. The circuit, as you have drawn it, can not and will not work for any pupose that I can devine. I don't understand either WTH you are asking for or about with respect to post #9
 

Thread Starter

Mark34

Joined Sep 23, 2016
24
hi Mark,
In post #9, the transistor Base is shorted to the transistor Emitter…it will not work.
E
In post #10 is the same problem transistor Base is shorted to the transistor Emitter...what I am asking about is just to charge the capacitor to 250V than with a switch disconnect the charging thing and keep the cap charged.
 

Papabravo

Joined Feb 24, 2006
18,153
In post #10 is the same problem transistor Base is shorted to the transistor Emitter...what I am asking about is just to charge the capacitor to 250V than with a switch disconnect the charging thing and keep the cap charged.
No, it is the short from the base to emitter that is the problem. If you remove it then the capacitor will keep charging forever, untill something discharges it or breaks down.

1637263850173.png
 
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