Standard Monitor Flyback Transformer with new primary. Jul 2, 6. The voltage will rise up to the breakdown voltage of the mosfet, where it stops since the mosfet is avalanche rated this does no harm, and only produces heat in the mosfet. The first is to use an optocoupler on the secondary circuitry to send a signal to the controller. Simply take the HV lead and bring it near the pins on the bottom. Can anyone comment on these? The ground pin can be found by finding the pin the HV arcs to the most.

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So, i came along this site http: To obtain a high frequency variable duty cycle drive signal we can use the timer.

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Jul 2, 5. If you’re getting a drive signal out of the circuit, you are probably not connected to the correct primary. Since some energy is avalanched in the mosfet, adequate heatsinking of the IRFP is required. The third consists of sampling the voltage amplitude on the primary side, during the discharge, referenced to the standing primary DC voltage.

Jun 24, 2. TV flybacks are generally designed for upper audio frequencies, which is the cause of the high pitched noise heard from a muted TV. For a different frequency range you can use a timer calculator or just experiment to find new capacitor and resistor values.


Since flyback transformers use a ferrite core they need vastly different operating conditions than an iron cored mains transformer. Just did It works perfectly fine, through performance is not the same as a proper high frequency driver – i get lower voltage out of the system.

Flyback converter – Wikipedia

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This is a pretty standard astable design.

Basically just check that everything is wired correctly, if it is, check that all the parts are functioning. Jun 24, 3.

However, this is not possible since the primary has significant inductance. You can check for a frequency by replacing the flyback with a speaker. The internal primary can be found by measuring resistance. Both require a signal related to the output voltage.

What that means is that the mosfet is turned on by the timer, and current starts to flow through the primary winding. Try switching the primary leads, since the flyback is rectified by a single diode, which makes polarity is important.

This is caused by a false primary or wrong phasing. This simple driver circuit is quite efficient if tuned correctly, and in some cases quite powerful. This topology is now replacing ringing choke converters RCCs in applications such as mobile phone chargers.

Flyback converter

In fact flyback transformers aren’t really conventional transformers at all, but coupled inductors which means they should be driven differently. For the mosfet I used an IRFP, though any mosfet with a breakdown voltage above V and “avalanche rated” will work.


The third technique, primary-side sensing, can be as accurate as the first and more economical than the second, yet requires a minimum load so that the discharge-event keeps occurring, providing the opportunities to sample the 1: If the output is weak, the primary polarity may need reversing.

I’ve been experimenting with the common two-transistor driver design with great sucessbut it needs VDC, and i want to keep the design as simple as possible as i want to build two small standalone HV displays a Jacob Ladder and a Plasma Globe, both working fine already.

There are three common ways to generate this voltage. I can’t measure it, of course, but it’s clearly making shorter arcs. Use a timer tester circuit. Some flybacks may have several winding which will appear to be primaries, in this case the real one can only be found by measuring inductance.

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