Hello. I´m learning english, excuse me if I make mistakes.

I´m building this flyback driver (I know this is dangerous, even lethal, and I´m being careful). I have 2 questions.

There are 2 power supplie. The 12-16V to run the oscillator and the 15-30V to run the flyback.

If I connect everything toguether inside the red square, the power supplies will be in parallel. I´m not sure if the terminal/ground with the blue cross have to be connected with the others. Obviusly the ground of the HV out doesn´t have to be conectes with the others gorunds, I think. So the

The other question is. If I run the oscllator without connecting the mosfet, Will I be able to measure the frequency with my multimmeter?

Thank you.

Kind regards

 

The grounds should be no problem for you, BUT, you need to remove the wire that is shown above pin 4 of the 555 going over to the 15-30V supply. As shown, the two power supplies are connected together. Disconnect the 15-30V supply from the primary of your transformer and measure the frequency. Also, you can find calculator on the internet that will tell you the frequency of your 555 oscillator based upon the resistor/capacitor values you input. Here is only one example:
https://daycounter.com/Calculators/NE555-Calculator.phtml

 

I´m not sure if the terminal/ground with the blue cross have to be connected with the others

The power supply grounds do need to be connected together, so the MOSFET gets the signal from the 555.

 

Thank you!

 

I think I have done something wrong.

When I connect a 12V 1A power supply to the oscillator, I see a smal spark and if I connect de multimmeter in the gate and source at the begining shows diferent values between 2 and 100 hz, and a few seconds later, goes 0.

 

I think I have done something wrong.

When I connect a 12V 1A power supply to the oscillator, I see a smal spark and if I connect de multimmeter in the gate and source at the begining shows diferent values between 2 and 100 hz, and a few seconds later, goes 0.

No matter how sure you feel now of doing things right, please post the circuit that you are currently following, supposed to be correct.

 

No matter how sure you feel now of doing things right, please post the circuit that you are currently following, supposed to be correct.

Please, don´t kill me, I´m a benniger in electronics and also drawing is not my best skill.

The circuit


My interpretation over the PCB

I don´t show the MOSFET because is not relevant to measuring the frecuency

The result

 

Your IC pin numbering is incorrect.
5 6 7 8 should be 8 7 6 5.

 

I´m an idiot!!!!!

Thank you

 

good news!

The ne555 survived my stupidity!! hahaha

It gives 10-33 Khz. My frist oscilllator

Thank you all for your help!

 

The grounds should be no problem for you, BUT, you need to remove the wire that is shown above pin 4 of the 555 going over to the 15-30V supply. As shown, the two power supplies are connected together. Disconnect the 15-30V supply from the primary of your transformer and measure the frequency. Also, you can find calculator on the internet that will tell you the frequency of your 555 oscillator based upon the resistor/capacitor values you input. Here is only one example:
https://daycounter.com/Calculators/NE555-Calculator.phtml

I´m not sure about useing the calculator. If I want lower frequencies, What resistor should I change? For example to set the minimun frequency about 2 or 3 Khz

 

You should probably change the setting of the wiper on the potentiometer. The output voltage of a flyback converter are highly dependent upon the gate drive duty cycle and input power supply voltage. The the schematic will allow you to use the potentiometer to vary frequency and duty cycle at once.

You can change the frequency range and maintain the range of duty cycle, percentage wise, by changing the capacitor. If you want the frequency range to go down to 3 kHz and the range is now 10 kHz change the capacitor 10/3 times the value of the existing capacitor (which is not shown on your schematic).

 

You should probably change the setting of the wiper on the potentiometer. The output voltage of a flyback converter are highly dependent upon the gate drive duty cycle and input power supply voltage. The the schematic will allow you to use the potentiometer to vary frequency and duty cycle at once.

You can change the frequency range and maintain the range of duty cycle, percentage wise, by changing the capacitor. If you want the frequency range to go down to 3 kHz and the range is now 10 kHz change the capacitor 10/3 times the value of the existing capacitor (which is not shown on your schematic).

Yes, but with the potenciometer, the frequency goes from 10 Khz to 33khz

 

Make the capacitor 3x the value of the existing capacitor and see what you get.

 

Make the capacitor 3x the value of the existing capacitor and see what you get.

thank you for your answer

Which one? The 470uf or the 1nf?

 

I don't see timing capacitor in your wiring diagram but going by the schematic it is the
capacitor that is connected to pins 6 and 2 of the NE555.

 

A good tutorial on various circuits using the 555 can be found here:
https://www.electronics-tutorials.ws/waveforms/555-circuits-part-1.html

It shows how the resistance and capacitance is calculated to give the various outputs you may desire.

 

Thank you

 

A good tutorial on various circuits using the 555 can be found here:
https://www.electronics-tutorials.ws/waveforms/555-circuits-part-1.html

It shows how the resistance and capacitance is calculated to give the various outputs you may desire.

Hey, your link was very useful!

I have made a new oscillator folowing the instructions, more simple but with a bigger range (10Khz to 400 Khz)

Thank you very much