Where to buy new pulse rated aluminium electrolytics?
Adam, Sat Aug 18 2012, 07:52AMA google search brings up manufacturers' data sheets for various capacitors, epcos make them up to 2500uF @ 500v which sound great but I can't find anywhere that sells them in small (~10) quantities.
Where can I buy large (>200J) pulse rated caps?
Re: Where to buy new pulse rated aluminium electrolytics?
Thomas W, Sat Aug 18 2012, 08:28AM
The question you need to ask yourself, i think, is how much money do you have to spare? my personal dream is to work up the funds for one of these:
wether i will ever get one... it seems unlikely
Thomas W, Sat Aug 18 2012, 08:28AM
The question you need to ask yourself, i think, is how much money do you have to spare? my personal dream is to work up the funds for one of these:
wether i will ever get one... it seems unlikely
Re: Where to buy new pulse rated aluminium electrolytics?
Adam, Sat Aug 18 2012, 08:41AM
I would be happy to spend $1000 on capacitors for this project, but size and weight are important factors, hence why I want to go with light energy dense Aluminium electrolytics over Oil and Paper Steel case capacitors
Adam, Sat Aug 18 2012, 08:41AM
I would be happy to spend $1000 on capacitors for this project, but size and weight are important factors, hence why I want to go with light energy dense Aluminium electrolytics over Oil and Paper Steel case capacitors
Re: Where to buy new pulse rated aluminium electrolytics?
Ash Small, Sat Aug 18 2012, 11:30AM
You can E-mail Epcos directly using the link below.
They will be able to give you details of your local distributor, etc.
,locale=en.html
Ash Small, Sat Aug 18 2012, 11:30AM
You can E-mail Epcos directly using the link below.
They will be able to give you details of your local distributor, etc.
,locale=en.htmlRe: Where to buy new pulse rated aluminium electrolytics?
Adam, Sat Aug 18 2012, 12:11PM
Unfortunately all the Epcos distributors I can find don't carry their pulse rated range
Adam, Sat Aug 18 2012, 12:11PM
Unfortunately all the Epcos distributors I can find don't carry their pulse rated range
Re: Where to buy new pulse rated aluminium electrolytics?
Pinky's Brain, Sat Aug 18 2012, 12:39PM
How about these :
Meant for strobe lights, so slightly slower than the photoflash/pulse capacitors ... but coilguns have relatively slow discharges to begin with. These are rated for 1 ohm loads, which gives you a RC time of 120 us ... plenty fast. You have to put 15 or so in parallel of course.
Pinky's Brain, Sat Aug 18 2012, 12:39PM
How about these :
Meant for strobe lights, so slightly slower than the photoflash/pulse capacitors ... but coilguns have relatively slow discharges to begin with. These are rated for 1 ohm loads, which gives you a RC time of 120 us ... plenty fast. You have to put 15 or so in parallel of course.
Re: Where to buy new pulse rated aluminium electrolytics?
Forty, Sat Aug 18 2012, 09:55PM
why you'd want to spend that much on a 120uF 450 volt capacitor is beyond me.
This guy has a bunch of capacitors for sale at great prices. enjoy.
Forty, Sat Aug 18 2012, 09:55PM
why you'd want to spend that much on a 120uF 450 volt capacitor is beyond me.
This guy has a bunch of capacitors for sale at great prices. enjoy.
Re: Where to buy new pulse rated aluminium electrolytics?
Pinky's Brain, Sat Aug 18 2012, 10:35PM
You pay for the name and the guarantee that it will work under certain conditions ... someone making an airplane or landing strobe light probably wants those. Someone making a coilgun should probably just look at best ESR for the $ and hope for the best :)
Pinky's Brain, Sat Aug 18 2012, 10:35PM
You pay for the name and the guarantee that it will work under certain conditions ... someone making an airplane or landing strobe light probably wants those. Someone making a coilgun should probably just look at best ESR for the $ and hope for the best :)
Re: Where to buy new pulse rated aluminium electrolytics?
Adam, Sat Aug 18 2012, 11:27PM
Thank you all for your responses. I think I need to really evaluate what's most important, and as Pinky's Brain said, just worry about getting the ESR as low as possible.
I was seeking Pulse related caps because of their long lifespans at high current discharge cycles, their low ESR and high discharge current capabilities.
Adam, Sat Aug 18 2012, 11:27PM
Thank you all for your responses. I think I need to really evaluate what's most important, and as Pinky's Brain said, just worry about getting the ESR as low as possible.
I was seeking Pulse related caps because of their long lifespans at high current discharge cycles, their low ESR and high discharge current capabilities.
Re: Where to buy new pulse rated aluminium electrolytics?
Dr. ISOTOP, Sun Aug 19 2012, 12:10AM
If its for a personal project, you're pay a lot for an official guarantee, when standard electrolytics have been hobbyist-proven to work fine.
Dr. ISOTOP, Sun Aug 19 2012, 12:10AM
Adam wrote ...
Thank you all for your responses. I think I need to really evaluate what's most important, and as Pinky's Brain said, just worry about getting the ESR as low as possible.
I was seeking Pulse related caps because of their long lifespans at high current discharge cycles, their low ESR and high discharge current capabilities.
Are you constructing a commercial product, or a piece of lab equipment?Thank you all for your responses. I think I need to really evaluate what's most important, and as Pinky's Brain said, just worry about getting the ESR as low as possible.
I was seeking Pulse related caps because of their long lifespans at high current discharge cycles, their low ESR and high discharge current capabilities.
If its for a personal project, you're pay a lot for an official guarantee, when standard electrolytics have been hobbyist-proven to work fine.
Re: Where to buy new pulse rated aluminium electrolytics?
Sulaiman, Sun Aug 19 2012, 12:45AM
I agree with the use of 'common' electrolytic capacitors,
make sure that the voltage is not reversed - (reliable diode)
In terms of capacitance/cost and esr/cost and esl/cost
an array of smaller electrolytics is better than one large electrolytic.
Commercial dc bus capacitors often consist of many 'push-fit' electrolytic capacitors
in series/parallel arrays. (opposite sides of a double-sided pcb as the bus voltages)
To be safe,
make part of your wiring using wire small enough to act as a fuse if things go wrong.
Sulaiman, Sun Aug 19 2012, 12:45AM
I agree with the use of 'common' electrolytic capacitors,
make sure that the voltage is not reversed - (reliable diode)
In terms of capacitance/cost and esr/cost and esl/cost
an array of smaller electrolytics is better than one large electrolytic.
Commercial dc bus capacitors often consist of many 'push-fit' electrolytic capacitors
in series/parallel arrays. (opposite sides of a double-sided pcb as the bus voltages)
To be safe,
make part of your wiring using wire small enough to act as a fuse if things go wrong.
Re: Where to buy new pulse rated aluminium electrolytics?
Adam, Sun Aug 19 2012, 04:39AM
Comparing the ESR of lots of small caps in parallel vs a few large ones is good advice Sulaiman and will certainly be an important consideration.
Dr. ISOTOP, I am building this for someone else, so since it's not my money I'm spending I'm prepared to spend the extra if it means there is less chance of a component failing!
Adam, Sun Aug 19 2012, 04:39AM
Comparing the ESR of lots of small caps in parallel vs a few large ones is good advice Sulaiman and will certainly be an important consideration.
Dr. ISOTOP, I am building this for someone else, so since it's not my money I'm spending I'm prepared to spend the extra if it means there is less chance of a component failing!
Re: Where to buy new pulse rated aluminium electrolytics?
grythumn, Wed Sept 12 2012, 08:48PM
Assuming you mean the b43415c6258a000, arrow europe has 50-odd of them in stock for about ~$50 each.
Just pick some candidate part #s, and run them through the (fairly lengthy) distributor list.
,locale=en,typeId=distri,countryId=US,stateId=.htm
l
-R C
grythumn, Wed Sept 12 2012, 08:48PM
Adam wrote ...
A google search brings up manufacturers' data sheets for various capacitors, epcos make them up to 2500uF @ 500v which sound great but I can't find anywhere that sells them in small (~10) quantities.
Where can I buy large (>200J) pulse rated caps?
A google search brings up manufacturers' data sheets for various capacitors, epcos make them up to 2500uF @ 500v which sound great but I can't find anywhere that sells them in small (~10) quantities.
Where can I buy large (>200J) pulse rated caps?
Assuming you mean the b43415c6258a000, arrow europe has 50-odd of them in stock for about ~$50 each.
Just pick some candidate part #s, and run them through the (fairly lengthy) distributor list.
,locale=en,typeId=distri,countryId=US,stateId=.htm
l-R C
Re: Where to buy new pulse rated aluminium electrolytics?
Yandersen, Thu Oct 04 2012, 03:26AM
I have those:
IMO, only this type of caps are suitable for coilgun "built the right way". As those are non-polar, no diode required for protection, which also gives possibility of short pulse duration which length strictly determined by caps' capacitance and coil' inductance (so there could be NO suckback!). Low ESR of this type of caps contributes greatly as well as low parasitic inductance. Sure, film caps are larger than electrolythics for the same energy stored, and price is higher too. But I assure you, that efficiencies gained by non-polar system do cover those disadvantages. By my exp, the main problem in non-polar system is the connection between the charger and the capacitor bank. During coil's firing voltage of caps is reversed, and high current starts to flow directly through the secondary coil of the transformer, frying out output rectifiers and the trans. The ugly solution is to disconnect the charger by a switch just before firing, then fire using the other switch. Headache for the gunner, used to push one trigger (currently I'm working on automated system driving the charger and mosfet switch). And if sequence is messed up, pieces of rectifiers from charger got accelerated in random directions together with the bullet...
With the caps linked above (I used 4 of them in parallel) I have achieved efficiency of 4+% from single coil and 6.66% from 2-stage coilgun (using recuperated 34% energy left from first stage), with second stage showing efficiency of 12+%. Feel the difference from "standard" results of 1%? And I'm sure that it could be much better if I had wire thicker than 0.7mm.
So give a try to non-polar caps - they deserve it. But stack-constructed ones, just as on the link above - not the cylindrical-shaped, as those have no advantages over regular electrolythic. Stack-constructed film caps have extrimely low ESR and ESL, which is just what is needed for coilgun, and they allow reverse charging giving an easy way for energy recuperation and letting us free from using "suckback diode". Think about it.
And BTW, sorry for offtop about film caps, but I think the topic has such strict name just because noone yet really considered not electrolythic caps as those to have for coilgun, which is not fair, IMHO.
Yandersen, Thu Oct 04 2012, 03:26AM
I have those:
IMO, only this type of caps are suitable for coilgun "built the right way". As those are non-polar, no diode required for protection, which also gives possibility of short pulse duration which length strictly determined by caps' capacitance and coil' inductance (so there could be NO suckback!). Low ESR of this type of caps contributes greatly as well as low parasitic inductance. Sure, film caps are larger than electrolythics for the same energy stored, and price is higher too. But I assure you, that efficiencies gained by non-polar system do cover those disadvantages. By my exp, the main problem in non-polar system is the connection between the charger and the capacitor bank. During coil's firing voltage of caps is reversed, and high current starts to flow directly through the secondary coil of the transformer, frying out output rectifiers and the trans. The ugly solution is to disconnect the charger by a switch just before firing, then fire using the other switch. Headache for the gunner, used to push one trigger (currently I'm working on automated system driving the charger and mosfet switch). And if sequence is messed up, pieces of rectifiers from charger got accelerated in random directions together with the bullet...
With the caps linked above (I used 4 of them in parallel) I have achieved efficiency of 4+% from single coil and 6.66% from 2-stage coilgun (using recuperated 34% energy left from first stage), with second stage showing efficiency of 12+%. Feel the difference from "standard" results of 1%? And I'm sure that it could be much better if I had wire thicker than 0.7mm.
So give a try to non-polar caps - they deserve it. But stack-constructed ones, just as on the link above - not the cylindrical-shaped, as those have no advantages over regular electrolythic. Stack-constructed film caps have extrimely low ESR and ESL, which is just what is needed for coilgun, and they allow reverse charging giving an easy way for energy recuperation and letting us free from using "suckback diode". Think about it.
And BTW, sorry for offtop about film caps, but I think the topic has such strict name just because noone yet really considered not electrolythic caps as those to have for coilgun, which is not fair, IMHO.
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