Author Options:

which flyback transformer should i get? irf 644? Answered

i am working an making a singing ark and is basically 555 timer circuitry powering it. which flyback should i chose to build it? i heard vintage ones are great but i dont know. i know some of them have a built in rectifiers. will that make the output suck?

i have the circuit im using below. i do have an ignition coil at hand. will that work? or is the resonant frequency way off? can i replace the irf 644 with a higher power chip? if so (i know i can) can you give me the specs of them?

i found an irf 740 that if 400V at 10A. will this work? is the amps too little?

  i would like to get most of all the stuff i need from Radioshack thank you in advance.


Q, how does a IRF9130 transistor attach to 3 wires when it only has 2 connectors?

I am attempting to understand how it will connect to the circuit, I am currently baffled.......


the casing itself is also a pin. i know, im not crazy about that "TO-3" design either. find somewhere on a spec sheet to find the pins. i wish they engraved it on there...

you can try another transistor there to see if it would work. but one with simalar / better specs

thanks, on ebay it shows to have 2 visible pins and now i know the 3rd is the case its self ;-) how about a capacitor battery? how do they work?

a capacitor is "A device used to store an electric charge, consisting of one or more pairs of conductors separated by an insulator."

it has two metal plates (like tin foil of metal sheets) with an insulating (like paper or plastic or aluminum oxide)

when a current goes through the cap; (well not exactly) the electrons build up on the negative end (where the battery "pumped" them) and "suck" electrons out the positive end. this results in a voltage across the leads.

the closer the plates are, the higher the capacity, but, the lower maximum voltage will be. (because a lot of voltage can cause the insulator to conduct) and the more area the plates have, the higher the capacity. connecting two capacitors in series will double the voltage but cut capacitance in half. 

now im sure your thinking big capacitors = battery; but the way they quickly charge/discharge makes them hard to use for this purpose. 


7 years ago

i buying the irf 740 i think the circuit will only draw about 3 amps

where did you find this diagram? i am building the same cuircuit. but i have two worries about this one. #1 the 3k and 2.2k resistors should be 10k and 9 k potentiometers so that you can tune the 555's out pute frequency with your flyback.#2 also the irf740 has a 0.55 ohm low on resistance (RDS(on)). when i think it is supposed to be under 0.1ohm, as with the irf250. this means the 555 might not put out enough power to work the irf740 but this may be countered with a simple transistor. i will be using the irf740 because i can get loads of them from where i work and cant find a irf250. i also have an irf640 i may try. ill be using a fly back i literally just ripped out of a computer monitor.

so please contact me, perhaps we can work on this together.

its a very cool project

#2 well i got it to work just fine until a spark got to my 555. and damaged it.
( ARGHH! my second one gone) i know that because as i went to touch it i felt a spark

(ps. the irf 250 doesn't look like it has a high enough voltage and may get killed.)

sorry i just glanced over just now and forgot to answer the rest of your question.

i calculated all those values to get me (as i remember) about 70% duty cycle and 19 KHz

the schematic is in the YouTube video, i copied it to paper, and rearranged the components and tighty-ed it up, and drew it in paint.