HV Desk Toy
..., Tue May 27 2008, 11:23PMI needed a birthday present for my sweetheart, so I decided that a new desk toy was in order
To keep things nonletal and simple, I decided to build on TDUs Candybox HV and use a camera charger (sans pcb, just the transformer, transistor, startup resistor and rectifier diode) to charge up a 6uf/450v cap (2x 3uf/450v in parallel) which is shorted into a 5 turn primary on a flybakck transformer using a 220v SIDAC.
Shrinking the charger circuit and adding the storage caps/SIDAC:
Add some power and a transformer, then start to build it into a box I built out of some leftover hardwood floring
Finished product:
Re: HV Desk Toy
Spedy, Wed May 28 2008, 12:23AM
Thats pretty cool! I would build one of these things but SIDACS are expensive from the sources I know of..
Hope she likes it!
Spedy, Wed May 28 2008, 12:23AM
Thats pretty cool! I would build one of these things but SIDACS are expensive from the sources I know of..
Hope she likes it!
Re: HV Desk Toy
Dr. Dark Current, Wed May 28 2008, 01:29PM
That looks pretty cool, especially with the two bare wires sticking from it... I bet everyone would guess what does it do even without applying the power! 
Dr. Dark Current, Wed May 28 2008, 01:29PM
That looks pretty cool, especially with the two bare wires sticking from it... I bet everyone would guess what does it do even without applying the power!
Re: HV Desk Toy
flannelhead, Wed May 28 2008, 01:59PM
Now as you got into the disposable camera business, why not to make her a small camera transformer powered SGTC?
flannelhead, Wed May 28 2008, 01:59PM
Now as you got into the disposable camera business, why not to make her a small camera transformer powered SGTC?
Re: HV Desk Toy
..., Wed May 28 2008, 02:33PM
Of course she liked it, although the first thing she wanted to do with it after she saw it was set something on fire with it
I was considering a sgtc/sstc, but decided that the simpler the better, since she is heading off to college (Notre Dame, Indiana) in a few months, so I am not going to be able to mess with it if it gets out of tune.
..., Wed May 28 2008, 02:33PM
Of course she liked it, although the first thing she wanted to do with it after she saw it was set something on fire with it
I was considering a sgtc/sstc, but decided that the simpler the better, since she is heading off to college (Notre Dame, Indiana) in a few months, so I am not going to be able to mess with it if it gets out of tune.
Re: HV Desk Toy
Weston, Thu May 29 2008, 03:07AM
Was the fly back a trigger coil? Could you direct me to a site that explains how to simplify the flash cameras, i have been planing to make something like this for months now.
Weston, Thu May 29 2008, 03:07AM
Was the fly back a trigger coil? Could you direct me to a site that explains how to simplify the flash cameras, i have been planing to make something like this for months now.
Re: HV Desk Toy
teslacoolguy, Thu May 29 2008, 03:50AM
the flyback is being used as a pulse transformer and the camera circut charges the capacitors and then the sidac discharges them into the primary coil.
teslacoolguy, Thu May 29 2008, 03:50AM
the flyback is being used as a pulse transformer and the camera circut charges the capacitors and then the sidac discharges them into the primary coil.
Re: HV Desk Toy
flannelhead, Thu May 29 2008, 12:51PM
However, not all charger circuits are the same. That tutorial works only for particular flash boards.
Another way is to do a bit of reverse-engineering to find out which parts belong to the capacitor charger circuit. Or you may find a ready-made schematic for your board with a little googling. If you're lucky, it's just a transistor, a resistor and the transformer. Desolder the parts from the board and make your own, more compact version.
flannelhead, Thu May 29 2008, 12:51PM
Weston wrote ...
Was the fly back a trigger coil? Could you direct me to a site that explains how to simplify the flash cameras, i have been planing to make something like this for months now.
There's a fine tutorial on Youtube. Was the fly back a trigger coil? Could you direct me to a site that explains how to simplify the flash cameras, i have been planing to make something like this for months now.
However, not all charger circuits are the same. That tutorial works only for particular flash boards.Another way is to do a bit of reverse-engineering to find out which parts belong to the capacitor charger circuit. Or you may find a ready-made schematic for your board with a little googling. If you're lucky, it's just a transistor, a resistor and the transformer. Desolder the parts from the board and make your own, more compact version.
Re: HV Desk Toy
rp181, Thu May 29 2008, 03:12PM
wouldn't the two caps in seris be 900v and 1.5uf?
rp181, Thu May 29 2008, 03:12PM
wouldn't the two caps in seris be 900v and 1.5uf?
Re: HV Desk Toy
..., Thu May 29 2008, 09:46PM
@weston, The charger was made by just looking at the traces on the charger pcb, and soldering the components on to their respective locations. Luckily the board I had was very simple, so it was easy to find which components were necessary.
@rp181, the caps are wires in parallel, the tvs fires at 220v so it was not necessary to have more than one series capacitor.
..., Thu May 29 2008, 09:46PM
@weston, The charger was made by just looking at the traces on the charger pcb, and soldering the components on to their respective locations. Luckily the board I had was very simple, so it was easy to find which components were necessary.
@rp181, the caps are wires in parallel, the tvs fires at 220v so it was not necessary to have more than one series capacitor.
Re: HV Desk Toy
Weston, Thu May 29 2008, 09:55PM
Yes but how does they flyback circuit work? there is 5 windings Verse the 6 that other designs use.
Weston, Thu May 29 2008, 09:55PM
Yes but how does they flyback circuit work? there is 5 windings Verse the 6 that other designs use.
Re: HV Desk Toy
..., Fri May 30 2008, 12:38AM
by the flyback circuit I assume you mean the camera charger? I honestly don't know what magic occurs in that circuit, I just took the parts off of the camera pcb and soldered remade the circuit without the pcb. The board I started with only had the 1 resistor and 1 transistor on it (aside from the rectifier diode and trigger circuit).
..., Fri May 30 2008, 12:38AM
by the flyback circuit I assume you mean the camera charger? I honestly don't know what magic occurs in that circuit, I just took the parts off of the camera pcb and soldered remade the circuit without the pcb. The board I started with only had the 1 resistor and 1 transistor on it (aside from the rectifier diode and trigger circuit).
Re: HV Desk Toy
Firefox, Fri May 30 2008, 03:27AM
It is hard to tell from the pictures, but are the caps discharged directly into the winding as a short? Or is there more to it than that? I just got a hold of 5 CRT monitors and I have three of the boards out already, and I as I was thinking of things to do with them, I stumbled onto this. I was thinking perhaps of using my mini CW multiplier to charge up one of my homemade 22uF 20kV caps and dumping it into something like this, but somehow that doesn't seem like a good idea.
Firefox, Fri May 30 2008, 03:27AM
It is hard to tell from the pictures, but are the caps discharged directly into the winding as a short? Or is there more to it than that? I just got a hold of 5 CRT monitors and I have three of the boards out already, and I as I was thinking of things to do with them, I stumbled onto this. I was thinking perhaps of using my mini CW multiplier to charge up one of my homemade 22uF 20kV caps and dumping it into something like this, but somehow that doesn't seem like a good idea.
Re: HV Desk Toy
Arcstarter, Fri May 30 2008, 03:39AM
Your kidding me right? Not about the idea, but the thing about a homemade 22uf capacitor? How did you do that?!
Anyway, i don't think a flyback could handle that. If you already have 20kv why do you need anymore? The only way to get a whole lot more is a tesla coil. Ha i am prolly wrong about that. You can use a marx generator. My favorite is uzzors's. It was made with all simple stuff, but produces quite a spark!
Arcstarter, Fri May 30 2008, 03:39AM
Firefox wrote ...
It is hard to tell from the pictures, but are the caps discharged directly into the winding as a short? Or is there more to it than that? I just got a hold of 5 CRT monitors and I have three of the boards out already, and I as I was thinking of things to do with them, I stumbled onto this. I was thinking perhaps of using my mini CW multiplier to charge up one of my homemade 22uF 20kV caps and dumping it into something like this, but somehow that doesn't seem like a good idea.
It is hard to tell from the pictures, but are the caps discharged directly into the winding as a short? Or is there more to it than that? I just got a hold of 5 CRT monitors and I have three of the boards out already, and I as I was thinking of things to do with them, I stumbled onto this. I was thinking perhaps of using my mini CW multiplier to charge up one of my homemade 22uF 20kV caps and dumping it into something like this, but somehow that doesn't seem like a good idea.
Your kidding me right? Not about the idea, but the thing about a homemade 22uf capacitor? How did you do that?!
Anyway, i don't think a flyback could handle that. If you already have 20kv why do you need anymore? The only way to get a whole lot more is a tesla coil. Ha i am prolly wrong about that. You can use a marx generator. My favorite is uzzors's. It was made with all simple stuff, but produces quite a spark!
Re: HV Desk Toy
Firefox, Fri May 30 2008, 03:59AM
Oops, I meant 22nF heh. Or I just used 1000 of my 22nF caps to make a 22uF cap. But in all seriousness, do you think a flyback could handle a 20kV input pulse for that split second?
Firefox, Fri May 30 2008, 03:59AM
Oops, I meant 22nF heh. Or I just used 1000 of my 22nF caps to make a 22uF cap. But in all seriousness, do you think a flyback could handle a 20kV input pulse for that split second?
Re: HV Desk Toy
Arcstarter, Fri May 30 2008, 04:35AM
I would say if you kept the gap small on the flyback output and the trigger gap on the cap(figuring you would use a spark gap as a trigger)it could probably go through a few pulses( more like 100's).
Arcstarter, Fri May 30 2008, 04:35AM
Firefox wrote ...
Oops, I meant 22nF heh. Or I just used 1000 of my 22nF caps to make a 22uF cap. But in all seriousness, do you think a flyback could handle a 20kV input pulse for that split second?
Well i did make a flyback driver with a tesla coil circuit. It was about 2kv transformer from a bug zapper and it was a .5nf capacitor. I would say that the flyback failed shortly after because i drove it too hard with that circuit, but it was a very small flyback putting out quite long but thin sparks. Oops, I meant 22nF heh. Or I just used 1000 of my 22nF caps to make a 22uF cap. But in all seriousness, do you think a flyback could handle a 20kV input pulse for that split second?
I would say if you kept the gap small on the flyback output and the trigger gap on the cap(figuring you would use a spark gap as a trigger)it could probably go through a few pulses( more like 100's).
Re: HV Desk Toy
rp181, Fri May 30 2008, 01:14PM
heh, i tried that with a SGTC, arcs were crappy.
rp181, Fri May 30 2008, 01:14PM
heh, i tried that with a SGTC, arcs were crappy.
Re: HV Desk Toy
Weston, Sun Jun 22 2008, 02:12AM
does anyone know if it would work with two inverse flash bulb trigger coils? They output over 5kv.
Weston, Sun Jun 22 2008, 02:12AM
does anyone know if it would work with two inverse flash bulb trigger coils? They output over 5kv.
Re: HV Desk Toy
..., Sun Jun 22 2008, 02:16AM
You could use the trigger coil, although they have a limited amount of power that they can output. It is certinly worth a try!
..., Sun Jun 22 2008, 02:16AM
You could use the trigger coil, although they have a limited amount of power that they can output. It is certinly worth a try!
Re: HV Desk Toy
teslacoolguy, Sun Jun 22 2008, 03:17AM
i have overdriven a trigger coil up to 10kv without any problems but the spark was very dim and i couldent feel anything when i used my finger as an electrode.
teslacoolguy, Sun Jun 22 2008, 03:17AM
i have overdriven a trigger coil up to 10kv without any problems but the spark was very dim and i couldent feel anything when i used my finger as an electrode.
Re: HV Desk Toy
Zeus, Thu Nov 12 2009, 12:55AM
In regards to pulsing LOPTs with 20Kv I pulse 8Kv into an ignition coil from my four stage multiplier made
with MOCs and driven by a MOT. The multiplier is the discharge cap as well as a means of increasing voltage.
Zeus, Thu Nov 12 2009, 12:55AM
In regards to pulsing LOPTs with 20Kv I pulse 8Kv into an ignition coil from my four stage multiplier made
with MOCs and driven by a MOT. The multiplier is the discharge cap as well as a means of increasing voltage.
Re: HV Desk Toy
..., Thu Nov 12 2009, 05:01AM
Wow, talk about reviving old threads!
In any case, you won't really get a whole lot more output with a 20kv capacitor vs my 400v capacitor, because the output voltage is limited primarily by core saturation (which scales as the inverse of maximum flux density in the core * core area), so a higher voltage pulse doesn't really help.
You can get improvement by increasing the pulse energy, which will give a hotter spark, and I believe to a lesser degree by using a faster pulse, or using a larger gap in the flyback core.
And while I am here I should post some relevant information:
-yes- the caps are shorted directly into a 5 turn primary using a 220v SIDAC, no fanciness involved.
-I have written a web page which has slightly more (if not just different) information about the system up at (although be warned we are doing server maintenance, and the link may be intermittent over the next week or so)
..., Thu Nov 12 2009, 05:01AM
Wow, talk about reviving old threads!
In any case, you won't really get a whole lot more output with a 20kv capacitor vs my 400v capacitor, because the output voltage is limited primarily by core saturation (which scales as the inverse of maximum flux density in the core * core area), so a higher voltage pulse doesn't really help.
You can get improvement by increasing the pulse energy, which will give a hotter spark, and I believe to a lesser degree by using a faster pulse, or using a larger gap in the flyback core.
And while I am here I should post some relevant information:
-yes- the caps are shorted directly into a 5 turn primary using a 220v SIDAC, no fanciness involved.
-I have written a web page which has slightly more (if not just different) information about the system up at
(although be warned we are doing server maintenance, and the link may be intermittent over the next week or so)Print this page