first boost converter

[Dr_Doggy]

hey look i got my first boost converter working from this schematic:

https://www.daycounter.com/LabBook/BoostConverter/BoostConverterSchematic.gif

im using 0.01uf on c1, 440mH on my inductor, and a tip121 for the transistor,

12v source, and switching it at 1-2khz, to obtain a nice output of 200v,

current is small <10ma max on source


but i am in want of more boost, either double or x20, but how do i do this?:
should i double my source voltage?
or double my inductor size?

also my tip121 datasheet says only 80-100volts at the collector, so far its holding together fine, but is there a better one i should use?


also i though of putting a voltage doubler circuit on it, one with caps and diodes, but i was not able to get it going

 

[panic mode]

cannibalize any CRT monitor or TV and you easily get 15-30kV

 

[Dr_Doggy]

yup, thats one thing i dont like about this new electronics recycling is that my parts are so hard to come by now, and the plants wont release their inventory.

i have my dual 2n3055 flyback driver, and tried my new zvs driver on a new(old)flyback, although i think the flyback was toast, since there was arcing coming out of the ceremic and in to my primary.

however i resorted to this option since i am trying to compact this charger circuit to watch size, this is for a pulse charger, so charge time I am not worried about, my specific end goal here is to simulate a piezo spark similar to ones in bbq lighters,

i got:
**broken link removed**
and wired the triggger part of the circuit like this:
https://repairfaq.cis.upenn.edu/sam/fflash1.gif

using my 200v boost converter as the charge circuit, maybe i need to check my wiring, but i did not see any spike on the scope at the 6kv side, prolly since the flash charge was so small, i notice the boost converter has little current also, and the load draw from the scope even causes volts to drop a bit,

i have also tried a voltage multiplyer on the output and a darlington config of 2 boosters, but i am unable to get past that 200v, infact both those additions failed, prolly a wiring issue on my behalf.

ideally i'd like to use that transformer listed above, but i thought i'd stop and "figure out where i am" here


edit: actually even 400v would be good for now, but i have even expanded to use this circuit, but everything still sits at 200v at output:
**broken link removed**

...id still like to get up to my 6kv thou

 

[Dr_Doggy]

k, got it by changing a cap with an inductor as such!
**broken link removed**

now @ 400v!!! next step to 6k!

 

[Dr_Doggy]

ya, the recycling depot wont let me dumpster dive

 

[MrAl]

Hi,

Why the extra caps and inductor?

Also, you are not showing any of the values of the components so it's not possible to say what will happen exactly. And it would be nice to know the series resistance of any and all inductors because that plays a big part in these converters. And you have to show what type of diodes are being used too.

 

[panic mode]

ya, the recycling depot wont let me dumpster dive

LOL, isn't that something...

they could occasionally get people working for free to strip covers etc for a chance to reuse some of the stuff...

 

[Dr_Doggy]

or at least do as the auto wrekers do,...


extra parts?, that is one thing I have never done!
**broken link removed**
the schematic used here was needed as the boost converter, and a voltage doubler, and actually i did 2 doubling stages....i found that using a typical diode capacitor system didn't work, im guessing due to a dc output at the booster? who knows, but buy swapping those caps in to inductors did the trick,
however i am finding that when i add the tank cap at the end it seems to bring my volts down again to 200v???

i will check my primary inductor's resistance next, its 450 000 uh, so you are prolly right about high resistance...brb!

 

[WTP Pepper]

Old car ignition coils are equally effective.

 

[Dr_Doggy]

look! got it up and running, here is the servo reload turret aswell, along with 2x200uf caps, charging to 300v fires a bullet clear across the room! 450v is caps max, but the other caps are only 300v so i dont want to stress them too much.
all controlled with my pic16f688,


the bigger coil works much better now, delivering at 1.5 amps, only problem is the 2khz ring it runs at, ohwell prolly better to hear it charging. and in the process of mounting on my roger robot
https://www.electro-tech-online.com/members/dr_doggy-albums-roger-robot.html


BUT i am going to do another circuit more like the first one, with low amps, and a smaller transistor,, my goal is to do a slower charge time (&current), but higher voltage(6kv), most important is it is to be watch size, ish, which i was hoping this little guy could help with:
**broken link removed**
but I am still not successful at hacking the all mighty transformer yet...



(the photos show the circuit with the new coil and 400v mosfet on my heatsink)