high voltage photo flash capacitor charger

[audioguru]

im not useing a blinking led..... and the led blinks like neon lights in camera flash circuits do when they are charged up[/charge]
I have no idea how a single transistor can blink an LED without using a transformer for positive feedback. It's easy to make a neon bulb blink by feeding it and a capacitor across it with a resistor.


I have no idea how many volts are "max feelable volts". 300V? 1kV? 3kV?


Of course. The 1M resistor is drawing current out of the charging. Maybe it should use a high input impedance darlington transistor and a 22M resistor. You could make your own darlington transistor:

[steven]

thankyou audio guru, my first high voltage photo flash capacitor  charger, charges up really fast as the flyback is similar to the one i used in this second high voltage photo flash capacitor charger , i dont now why the led blinks on and off as its chargeing  maybe , something there to look into

[steven]

:)ive did some more exsperiments and testing of the high voltage photo flash capacitor charger and by the fels of the charge on the capacitor it must be over chargeing so it appears to be ok but you can use a current limiting resister to help preserve the life of the capacitor , i  charged up a 350 volts 330uf high voltage photo flash capacitor and i discharged it a number of times befor it died so i performed an autopsy on the capacitor and found its foil to be in ok condition and with no damaged whats so evr in the foil electrodes but they were grey in colour and so brittle looking you only have to bend it to much or sqeeze to till it breaks or crumbles to bits but when i took the capacitor foil roll out of its can i noticed some electrolyte soloution at the bottom of the can so i think what happend was to much of that electrolyte got boiled away thuis stopping the cap from working , i got the same problem with another circuit i once made and this one if you short it out i fried all the caps and they look in good condition but there values were much less as if there electrolytes were boiled away i think it was and i tested all the diodes on the same board and they were all ok so it was the capacitors at fault .

[audioguru]

Hi Steven,
Thanks for doing an autopsy on your photo-flash capacitors that died. ;D
It is interresting that they show signs of too much discharge current. They probably have a very low internal resistance and therefore their current must have been high enough when you shorted them that it cooked them. ;D

[steven]

thankyou audio guru  at least someone apreciates me autopsy on dead high voltage photoflash capacitor  its strange how the foil is grey and brittle and breaks so easily and with no holes in it or visible damage  i once pulled a microwave cap apart and its foil was still like foil and not grey but around 16 feet long or over and had holes in the foil down near the end as if the insulation was broken or punctured buy  arcs ,

[audioguru]

Hi Steven,
Metalized plastic film capacitors are self-healing. The metal film on the platic film is so thin that arcs caused by over-voltage just vapourises the metal where an arc occurs. ;D

[steven]

thankyou for the input, greatly apreciated , with the high voltage and current in the 350 volts photo flash capacitors i reckon i may be able to channel that voltage through the 35000 volts bridge rectifier i made of microwave oven diodes  at least it may give great reverse voltage protection , with that exsperimental high voltage bridge rectifier i never got to test yet that i posted to the high voltage stuff section  well im looking at the option of testing it on my simple hydrogen and oxygen from tap water exsperiment i posted to the topic , playing with hydrogen and see if i can speed da process up faster hope fully

[steven]

here are some of the latest pictures of the latest high voltage photo flash capacitor  charger , and included is that simple capacitor  charge indicator circuit  from the coil gun topic in the high voltage stuff section , of which  the indicateing led is above the neon globe on the front pannel of the unit now although i only have the end pannel and lid to do, all the wireing  except for the battery charge input to charge the battery up and the power switch and led have yet to be done

[steven]

:)

[steven]

the switch wires are finished and all i have to do is  get the terminal things for the battery and wire that up , so i used 2 jumper wires with insulated crockadile clips on the ends and ran them from the 12 volts lead acid cell high energy battery and , there was no action so a bit of testing and continiuity checking the thing is going so i put a 330 volts 120uf high voltage photo flash capacitor, up to the outputs and adjusted the 10k and 25k pot.  as for the capacitor charge indicater that worked so well when in line with the 350 volts photo flash capacitor whith the unit before this latest one  it dident work the same  and this one you can hear the high pitch sound of the flyback and the sound seemed to be beeping  and the led would flash  to indicate a charge but the neon was canceled out so i disconected the wire of the charge indicater and the neon came on so i made a few modifications by installing a switch to switch on the capacitor charge indicater circuit iether when the capacitor is chargeing  or when the unit is off and the charged capacitor is still hooked up so i can use it that way  with or without the neon comeing on , now the flyback driver circuit or vortex canon circuit which is what the driver circuit really is has the uf4007 high spedd diodes in it and the 1k resisters are metal filom types with 2 per cent tolerence . and the electro in the circuit is 2200 uf but at 50 volts and not 35 volts so the test went ok with these results in chargeing the 330 volts high voltage photo flash capacitor at  the value      mentioned earlyer , the capacitor charged up fully or more and the feelable voltage across the capacitor terminals  was much more stronger or powerfuller so this thing seems to really put a big charge that packs a high current punch when i  touch the capacitor terminals with my fingers  so now i just have to finish the panel and lid and its ready for some hydrolysis exsperimenting and others

[audioguru]

Hi Steven,
A 1N4007 rectifier diode isn't high speed, it is a slow mains rectifier diode rated at 1kV. A high speed rectifier diode would charge the capacitor quicker and the driver transistor would operate cooler.

Your high voltage indicator circuit loads down the capacitor voltage because the values of the resistors in its voltage-sensing input voltage divider are too low. Didn't we talk about it before? I think it uses a 1M resistor which draws 350uA from the capacitor at 350V. The 2N3904 LED driver transistor needs only 1/10th that much current into its input to light an LED. ;D

[steven]

hello audio guru i must of got it wrong the diodes are uf4007 high speed diodes  and the capacitor charge circuit  works different when intergrated into this one ,than it did with the other high voltage photoflash capacitor charger, but ive modified it by adding a switch so i can monitor the cap charge at intervals dureing the chargeing process  as this one cuts the neon out  so ill use it for short tests for cap charge  so the neon stays on whgen charged

[audioguru]

Hi Steven,
You are absolutely correct! ;D
Your uf4007 rectifier diode is fast. It is much faster than a 1N4007.
You made a good choice. ;D

A uf4007 has a max reverse recovery time of 75ns.
A little 1N4148 diode 's time is only 4ns, but its voltage and current ratings are too low for your application.

The neon bulb also has a current that will slow-down the capacitor's charging and drain it after it has charged.

[steven]

audio guru this circuit seems to take a little longer to charge the cap but im exsperimenting with the setttings to get it charged faster  i used a 3 way togel switch with center off position to test the capacitor and after that i leave it on more till it charges the capacitor back up as it seems to drain the capacitor  a fair bit when i used the charge indicater circuit , unlike before ,with the other capacitor charger the capacitor charge indicater works great with the c ircuit runing and the neon still comes on and the capacitor charge indicater led dose blink when the cap charges . this one here is acting differently  but ok ,

[steven]

here is the finall picture of the latest high voltage photo flash capacitor charger fully tested and working great

[steven]

now to put some more exsplanation into this ,to strt with the circuit box is my home made circuit box made from pvc water pipes and the framework is plastic corcner moulding , the circuit board is a prototype circuit board and i used tinned copper wires for the tracks, and the timer inetergrated circuit is at the front plugged into a timer socket soldrd to an ic mounting board , so changeing it is easy so its a matter of unplugging it and pluging in a new one when needed and the wires run to the main board where the matrix  pins are  and the ifr540 n channel mosfet is at the rear its attached to a heatsink and the wires run from it through 3 tniy holes to the orange mov on a tag strip the mov protects the mosfet and the wires run from the tag strip to there positions on the board so less components on the board make it easyer to biuld , the mosfet and the timer would be the most likely parts to ever go first so they are exsternal so replaceing them is easy , with the mosfet just unsolder the 3 wires and undo the nut and slip it off and place a new one on , you can use the irf7040 n channel mosfet to ,  i used bits of pvc cut to shape and heated till its soft and with a screw driver and pair of pliers shaped them, to use as wire holders to secure them to the inner box 

[steven]

:)i did some more tests  with the high voltage photo flash capacitor charger, now if i hook up a photo flash capacitor to the charger outputs when it charges up the neon comes on  and when i put a 1200uf large 200 volts electrolytic capacitor the neon doent come on in the same time frame as it dose when i charge the photo flash capacitor up in. but anyhow i used my judgement and assumed the cap had got enougth charge in it so i isolated it from the capacitor charger and used the charge to test an exsperimental coilgun with it , i used a pen caseing and wound ignition coil wire about 66 turns thats ten turns then another ten on top of that and so on and the last 6 turns on top then i use a short thin steel thin screw and inserted it into the coil so its front was about half way inside the coil then i dumped the charged 1200 uf 200 vdc cap intoi it and it flew 5 and a half feet so it worked , even though the coil could of been  made with a better gauge wire , more thicker. and i charged a photo flash cap up of unknown value and tried the same thing i discharged it into the coil with projectile in it and it flew out a short distance for the ,low value of the photo flash cap, at 330 volts ,

[audioguru]

Hi Steven,
Photoflash capacitors have much lower internal resistance than ordinary large HV caps.
If you put a bunch in parallel then they would take longer to charge but would pack more power.
Then make the coil gun with thicker wire and more turns and you will have a real gun!

[steven]

:)thankyou audio guru im working on it ill post details and pictures when all done and finished

[steven]

:)the high voltage photo flash capacitors dont take to long to charge up, but there values aint so high so at 330 volts they charge qiuckly. but when i use an electro like 1200uf at 200 volts they take longer to charge as it seems but the charger neon dosent come on then, so the capacitor charge indicater would have to be relyed on to light up its led  when the charge in the higher value electro is high enougth. now heres what ive tested the charged up 1200uf 200 volts electro on after i charged it for a short time  without waiting for the neon to come on , and without setting the capacitor charge indicater to flash its led when charged up to certain voltage. now its my first super simple coilgun here  so i needed a charged up capacitor to test on it so the high voltage photo flash capacitor was perfect for it , the coil i dident have to wind as it was allready on the plastic roll and the 16 or 18 gauge wire on it was ok  and the black thin tube for projectile launching was a perfect fit , through the center hole in the plastic reel with the wire allready on it  so i used a short screw and charged up one 200 volts capacitor at 1200uf and then dumped the charge into the coil and the screw shot out about 5 or more feet before it hit the cuboard so it works great for a coilgun power source  so ill be doing some more construction here to make and test a ring launcher useing the same high voltage photo flash capacitor charger

[steven]

:)

[steven]

:)audio guru that 350 volts capacitor charge indicater circuit you posted dident work it just blew the transisters  after the led blinked on bvriefly for a short time now the flasher led has a biult in resister so without one, i used a resister and led separate which should still work like the one transister version capacitor charge indicater dose  i tested both transisters out to confirm they are nackerd and the led still ok to , is this circuit from the net and has it been biult and tested .

[audioguru]

Hi Steven,
Maybe the 350V arced across the 1M resistor in the HV indicator circuit I posted.

[steven]

hello audio guru there wasent any arcing at all  i had no problems with the 1 transister version capacitor charge indicater and its current limitimg 1/2 watt resister is between the led and top pos rail  so ill make a few changes to the circuit you posted when i stock up on moe trannies and use the same setup  but with the 1/2/ watt resister at the top rail after the led

[audioguru]

So I guess you tried my circuit without any current-limiting for the LED. No wonder the transistor blew-up. :(