flybackhigh voltagemosfetmosfet-drivertransformer
I salvaged a flyback transformer from an old TV and used it in a single MOSFET driver like this:
I used 6 turns of insulated copper wire to make the primary coil with the centre tap and again 6 turns. I found the secondary ground on the flyback and tried drawing some arcs, but to my disappointment all what I got was a 2 mm arc.
Can someone please tell me why this is happening and if there is a way of correcting my circuit for larger arcs?
OK i guess since I got answers in comments, I will just answer this myself. I do have a bad Flyback!!!
WARNING: This circuit can produce LETHAL voltages and is provided for information only.
You cannot just use any old transformer. A salvaged fluorescent tube transformer is very unlikely to work.
If you don't (or can't) wind your own transformer then at least go for a transformer you know is designed for the job.
(1) Car ignition coil
(2) A line (flyback) transformer from an old CRT display
Both are designed and made to generate very high voltages
Things you should notice in this circuit.
(1) The 555 is decoupled from the 12V supply through a 56 ohm resistor (R3) and 100uF + 0.1uF (C1,C2). Try to get these capacitors connected as close to the pins of the 555 as possible (pins 1 and 8).
(2) The circuit does not require the 2N2222 transistor to drive the Mosfet. (Neither does your circuit). The 555 is quite capable of driving the gate of a Mosfet which is essentially a small capacitor that needs a sufficiently large voltage change (0 -12V is fine) and not a lot of current to turn it on and off.
(3) It uses diodes (D3,D4 - rated at 600V,3A)) to protect the Mosfet from voltage spikes and reverse voltage.
(4) It uses a different Mosfet - IRF640. The main differences are a higher maximum voltage and a lower turn on resistance. The lower turn on resistance means LESS POWER (I^R) will be lost in the Mosfet and it will run cooler (although you still mount it with a heat sink).
Best Answer
use fewer turns for the primary, like 3 perhaps.