Re: Diode Rectifier Differences (Repost)

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Bert Hickman by way of Terry Fritz <teslalist-at-qwest-dot-net>" <bert.hickman-at-aquila-dot-net>

Matt,

Although your unpassivated diodes may not last 25 years, your Tesla Coil 
probably won't either. Go for the cheaper diodes - odds are they'll work 
just fine for as long as you'll need them to.  :^)

Best regards,

-- Bert --
-- 
Bert Hickman
"Electromagically" (TM) Shrunken Coins
Stoneridge Engineering's Teslamania
http://www.teslamania-dot-com

Tesla list wrote:
>Original poster: "by way of Terry Fritz <teslalist-at-qwest-dot-net>" 
><Mddeming-at-aol-dot-com>
>Hi Bert, Dave, All,
>        The manufacturer of all three variations of this diode is Diodes 
> Inc. and the vendor is DigiKey. The cases are all type DO-41. Since my 
> TCs spend the winter in an unheated, detached garage, it seems the glass 
> passivated diodes may be better, but I'm not sure they are  worth twice 
> the price.
>Thanks for the insight,
>Matt D.
>In a message dated 1/1/03 1:03:01 PM Eastern Standard Time, 
>tesla-at-pupman-dot-com writes:
>
>><bert.hickman-at-aquila-dot-net>
>>
>>Hi Matt,
>>
>>"Glass passivation" is a process that adds a protective layer of glass
>>above the PN junction (and sometimes the entire silicon die) to prevent
>>parameter changes or other degradation of the device under high humidity or
>>high temperature conditions. Glass passivated devices are commonly
>>specified where either high reliability or reliable operation under harsh
>>environmental conditions is needed, such as automotive, aerospace,
>>military, and telecommunications.
>>
>>Using industry standard part designations, the 1N5408 is unpassivated while
>>the 1N5408G is the same root device with glass passivation. For indoor
>>Tesla Coiling, either type can be used. From a performance standpoint, the
>>unpassivated device may be a bit more robust, since most vendors spec it
>>with a higher forward surge current rating. However, if your system will be
>>housed in area that's not temperature/humidity controlled (such as an
>>unheated porch or a pole barn), go with the 1N5408G device.
>>
>>The 1N5408-T and 1N5408G-T devices you have found are NOT industry standard
>>part designations, and I was unable to find ANY spec sheets that covered
>>them. While the latter part is _most likely_ glass passivated, it's not
>>clear that the 1N5408-T is (regardless of the seller's description). I'd
>>recommend using a different vendor and going with industry standard parts
>>so that you know exactly what you're buying.
>>
>>Good luck and best regards,
>>
>>-- Bert --
>>--
>>Bert Hickman
>>Teslamania, from Stoneridge Engineering
>>"Electromagically" (TM) Shrunken Coins
>>http://www.teslamania-dot-com
>
><dave-at-davidspeckmd-dot-org>
>
>  >Matt,
>  >My Dad used to make power semiconductors for GE, (which later became 
> Powerex).
>  >All the power semiconductors that they made were glass passivated --
>  >passivation indicating a treatment of the edges of the semiconductor dice
>  >to reduce hot spots caused by local differences in current flow.
>  >I believe that this is standard practice on all such devices, so you
>  >probably would not find any significant difference in performance between
>  >these three devices.  Were the prices all from one seller, or from
>  >different sellers?  They may also indicate differences in package types, or
>  >in guaranteed operating temperature ranges. or in permissible reverse
>  >leakage currents.
>  >HTH,
>  >Dave Speck
>  >>Hi Y'All
>  >>        Could some knowledgeable person explain the difference/advantage
>  >> between these diodes (if any) as applies to rectified TC supply?
>  >>
>  >>      1N5408        3A 1000V silicon rectifier  -at- $16.80/100
>  >>      1N5408-T     3A 1000V silicon and glass passivated rectifier  -at-
>  >> $19.24/100
>  >>      1N5408G-T  3A 1000V glass passivated rectifier -at- $30.30/100
>  >>
>  >>Thanks,
>  >>Matt D.
>