[GreenKeys] Rectifier voltage question...

[Peter Gottlieb]

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

> On Sep 18, 2019, at 10:07 AM, Ralph Mowery <rmowery28146 at earthlink.net> wrote:
> 
> The 1n400X series of diodes are rated for 1 amp and may be a little light for the service. Some 2 or 3 amp diodes rated 400 volts or higher would be better.
> 
> The selenium rectifiers do have a large voltage drop.  I could not recall if it was one or two volts per plate but somewhere in that range.  
> I had sent a message about wiring it for the 125 volt primary side to help account for that drop if replaced.
> 
> Ralph ku4pt
> 
> 
> -----Original Message-----
> From: greenkeys-bounces at mailman.qth.net [mailto:greenkeys-bounces at mailman.qth.net] On Behalf Of Dave Wade
> Sent: Wednesday, September 18, 2019 3:51 AM
> To: 'Peter Gottlieb'; GreenKeys at mailman.qth.net
> Subject: Re: [GreenKeys] Rectifier voltage question...
> 
> 
>> -----Original Message-----
>> From: greenkeys-bounces at mailman.qth.net <greenkeys-
>> bounces at mailman.qth.net> On Behalf Of Peter Gottlieb
>> Sent: 18 September 2019 04:19
>> To: E. <hanyou at xsmail.com>
>> Cc: Robert Downs via GreenKeys <greenkeys at mailman.qth.net>
>> Subject: Re: [GreenKeys] Rectifier voltage question...
>> 
>> 1N4007’s would be fine.
>> 
> 
> Don't selenium rectifiers have a high voltage drop, about 2v per plate. Won't simply replacing by silicon make the output voltage much higher.
> 
> Dave
> G4UGM
> 
> 
> 
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