[GreenKeys] Rectifier voltage question...

[Peter Gottlieb]

Sure. The limit is going to be that transformer which from the look of it can’t be much more than an amp. No harm in using 3, 5 or 6 amp diodes because as you point out they are all cheap. 


Peter

> On Sep 18, 2019, at 11:25 AM, Ralph Mowery <rmowery28146 at earthlink.net> wrote:
> 
> Peter I may have it wrong but I was thinking that supply was going to drive a magnet for a tape punch that was going to require about an amp of current.  There is not very much difference in the cost of higher current rated diodes when  buying less than 10.
> 
> You can get 10 or more 6A10 diodes off ebay from the US for about $6 shipped.  They are rated for 6 amps at 1000 volts.
> 
> If only for the 60 ma loop, then of course the 1 amp diode is plenty for that.  I have several 60 ma loops that have the 1 amp diodes in them and like you have ran them for years.
> 
> I am used to buying things in bulk and when I do , I tend to go way over ratings if the price is not that much. 
> 
> 
> Ralph ku4pt
> 
> 
> 
> 
> -----Original Message-----
> From: Peter Gottlieb [mailto:kb2vtl at gmail.com] 
> Sent: Wednesday, September 18, 2019 10:31 AM
> To: Ralph Mowery
> Cc: GreenKeys at mailman.qth.net
> Subject: Re: [GreenKeys] Rectifier voltage question...
> 
> Not sure why you consider a 1 amp diode light for driving a 60 mA loop.  They do have surge ratings to handle the capacitor charging. Do you know the selenium rectifier rating?
> 
> I have used that kind of diode in plenty such supplies over the years and never had a failure. 
> 
> In that supply, a 1/2 or 1/4 amp slow blow line fuse would seem appropriate. If the supply is 50% efficient (it will be way better than that!) a 1/4 amp fuse would support 110 mA of loop current. Of course if you want to support multiple loops you will need more but even a 1/2 amp fuse would support 3 loops with plenty of headroom and 1 amp diodes won’t be anywhere near their limits. 
> 
> 
> Peter
> 
> 
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