Making High Voltage

[George L.]

Hello,

I have been messing with a 555 IC and a 220:1 transformer trying to get a high voltage of about 1kV-2kV. Not working out to well. Insted of a 555 IC I am going to try to just use some transistors, caps, etc.

I found the circuit below. Just a LED flasher. I have it working properly on a breadboard. When I swap out the 10uF cap and put a lower value the LED flashes at a higher Hertz. 10uF is about 1Hz.

From the values in the circuit, how do I calculate the Hz the LED will blink at? (RC time constant or something lik that?)

Also, do you think it would be possible to hook up my small transformer from a camera flash where the LED is and create the high voltage I desire :twisted: . (Low mA )

I would need to change resistor values for more current and use a formula to get 60Hz. (what is the formula) :?

I don't know exactly what Hz the camera flash uses.

would really appreciate some help.

thanks,

George L.

 

[George L.]

Sorry, forgot circuit.

here it is...

 

[panic mode]

just what are you trying to do with 1-2kV voltage source?
is it supposed to be AC (60Hz?) or it will be converted maybe to DC?
how much current do you expect from such source? could it be
that your load is to heavy for such small source (i hope it doesn't
exceed some 0.1...0.2mA if you ware using 555 alone).

 

[Someone Electro]

My schocker can generate up to 3kV whith the right transformer.

And yea a timer alone wont output nearly enugh curent to drive anything big.You need a transistor or beter still a mosfet

Also i found mains trafromers backwards somtimes work better at a higer feqoency like 100 Hz That is some. Try to put a pot on the timer and tune the freq so you get the bigest output

 

[panic mode]

MOSFET is CMOS Field Effect Transistor... but it's a transistor.

 

[Russlk]

The 10uF capacitor is connected backward. When the PNP turns on, the NPN base-emitter junction is a diode that charges the cap to about 3 volts. When the cap is fully charged, the PNP collector starts to drop, which turns the NPN off and biases the NPN base to -3 volts. The time that it takes the 330K to charge the 10uF cap back up to +.5 volts determins the rep rate.

 

[Roff]

MOSFET is CMOS Field Effect Transistor... but it's a transistor.

Since we seem to be shooting for accuracy here...
CMOS actually means Complementary Symmetry Metal Oxide Semiconductor. It's a logic technology employing N-channel and P-channel MOSFETs.
MOSFET means Metal Oxide Semiconductor Field Effect Transistor.

 

[Roff]

I think that circuit needs a resistor in series with the 10uF cap to limit the transient base current of the NPN, which can be hundreds of milliamps otherwise. Also, I couldn't get it to oscillate in a simulation until I increased the 330k to considerably more than a megohm (I think I used 10Megs). It is probably dependent on the beta of both transistors.

 

[Someone Electro]

Have you tohght of a TV flyback? They can put out up to 20 000 V

 

[Nigel Goodwin]

Have you tohght of a TV flyback? They can put out up to 20 000 V

More than that, any non-portable colour TV will run at 25KV or greater.

 

[Someone Electro]

Modern ones are prety whimpy.

I just got a flyback runing here but im asking too much from it since the secudnary gets hot.When it comes to curent my homande secundary was better it made huge flaming arcs

 

[steven]

makeing high voltage

a flyback transformer driver circuit will do you can get great hv arcs from driveing a tranformer in reverse mode with the flyback transformer driver to , look in the high voltage stuff section in electronics lab