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Registered Member #2838
Joined: Fri Apr 30 2010, 07:55PM
Location: tehachapi, CA
Posts: 333
EASTVOLTRESEARCH- I have appriciated and respected your help and advice to both myself and others in the past. And, however I do agree with your statement, I do not feel that it was necessary or appropriate for you to crash my thread to resolve the issue between yourself and patrick. A private message to him would probably been more than adequate.
Patrick- I do greatly appreciate your offer to me but I am just a hobbiest so if you have spare parts that you are willing to part with, perhaps it would be better to send them to a student as suggested by eastvoltresearch. Don't get me wrong, I am usually open to accepting free items!
Teravolt- My biggest concern is taking the time to build the stacks and kill them shortly after. I do not want to spend a fortune on parts but time is valuable as well. If you wouldn mind maybe you could PM me some specs on your CW? It may make me feel slightly more confident on the 1n4007's if I can see what kind of a beating you are subjecting them to...
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
Oidium45 wrote ...
Patrick- I do greatly appreciate your offer to me but I am just a hobbiest so if you have spare parts that you are willing to part with, perhaps it would be better to send them to a student as suggested by eastvoltresearch. Don't get me wrong, I am usually open to accepting free items!
Yeah ok Odium45. the HER108's, I can spare some of those if he has a student in mind.
Oidium45 wrote ...
Teravolt- My biggest concern is taking the time to build the stacks and kill them shortly after. I do not want to spend a fortune on parts but time is valuable as well. If you wouldn mind maybe you could PM me some specs on your CW? It may make me feel slightly more confident on the 1n4007's if I can see what kind of a beating you are subjecting them to...
Yeah, I would like to see some of your work with the 1n4007 too, Teravolt. I think the deciding factor should be the fraction of current "hold back" versus conduction. Remember ther closer to the Trr value you get the more heating you have. I have never tried what Teravolt has with the 1n4007 + flyback, did you have many in series?
Also Odium45, if you are going to use that flyback in the pic you posted on the "super flyback" thread...Sweeeeet!
Registered Member #195
Joined: Fri Feb 17 2006, 08:27PM
Location: Berkeley, ca.
Posts: 1111
Hi all, I have found some uf4007 at 6.1c ea if you buy over 250
the data sheet is also there. The uf4007's have a Tff of 75ns and the Tff 2us if you buy the standard 1n4007 at 1.3c ea at over 250.
some of those genral purpace 12kv mot diodes are just a stack of 1kv dies in a package
Hi Oidium45 I am not sure what your budget is or how hard it is for you to get parts so I hope this will help. No one can design Hv equipment and do what we do with out some failures. We can show you what we have done that works for us. When I started the project in my picture I was curious whether diodes with a standard recovery time would work with a flyback. I am not sure weather uf4007 would have given me different results. To my knowledge I don't know whether some one has posted a thread for this experiment but I am sure other people have done it. When I posted my findings at my thread "2mev marx" Steve McConnor recommended adding resisters in series with my multiplier would help keep it from ending up a lump of useless silicon. I declined and it still works. if you want to play it safe use resistors.
so far I have been talking about diodes but capacitors are not all the same I would try 15kv disks if you can find them cheaply. I saw some Chinese ones on ebay. If you can get doorknob capacitors they work well, they are fairly robust if they are not over voltaged. the ones that I use are 30kv at 500pf. does any body have any better sources
Registered Member #834
Joined: Tue Jun 12 2007, 10:57PM
Location: Brazil
Posts: 644
I am using 1n4007s in stacks in a kind of semi-electronic electrostatic generator. The reason is that I found that they have an extremely low reverse current. Speed is not important in this case. I tried several, apparently from different makers, and the characteristics are consistent. Other diodes that I tried had leakage currents orders of magnitude greater, in the uA range at hundreds of volts, and were useless for my application.
Registered Member #2838
Joined: Fri Apr 30 2010, 07:55PM
Location: tehachapi, CA
Posts: 333
BTW, Here is a pic of the flyback(s) that I will be using. I am not sure about the center or right flybacks. They have not been tested. The one on the center is aged badly so I don't have too much faith in it. The right one used but appears to be in good condition. At least as far as the insulation is concerned.The one on the left I purchased as new old stock for a late 60's early 70's packard bell. The cap in the center is for size reference. It is a 30KV 1000pf. I have several of these along with 30KV 500pf's. I will likely be using these for my CW.
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
Oidium45 wrote ...
I am worried that the current would be too low with most of them. I am specifically looking at the NTE518 10Kv 3A
becareful with NTE they are a reseller not really a semi maker, the nte stuff i have is relabled from national, st, fairchild. maybe they have changed since ive used them last. but i try to stay away from them. they are mainly a replacement semiconductor for obsolete or near end-of-life product lines.
Oidium45 wrote ...
Otherwise Avnet has fairchild UF4007 for $0.055 for 500
or 1n4007 or $0.0142 for 1n4007.
based on what the many posts here suggest, i would go with your 1n4007's @1.4 pennies each. i learned quite a bit from your thread here Odium45.
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
Proud Mary wrote ...
Wouldn't it be simpler, cheaper, and neater to just buy diodes of the appropriate rating?
yeah if he can find the ratings he needs with low enuogh cost.
And to Teravolt, in your above full wave CW pic, how much cummulative time of operation do you have on that setup? the longer the time you have logged the better the 1n4007's are sounding. How much power are you putting into those 4 flybacks (at low V) ? How much power do you estimate is leaving the flybacks at HV?
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1n5399 vs 1n4007 for diode stack
