[Jukebox-list] Selenium Rectifier

[The Jukebox Junkyard]

    Don, all bridges have two full wave rectifiers inside. Both are used in 
circuits that use transformers that are not center tapped.  There are 
circuits that use center tapped transformers when you need both  positive 
and negative supplies. This circuit is used in some high powered amplifiers. 
Some use a large isolation capacitor to protect the speakers. This capacitor 
is connected to the center point of the transistor output that is at zero 
potential with no signal. This circuit was developed before complementary 
pairs came into use.Personally I prefer this system over later complementary 
circuits. They are easier to trouble shoot.  Some of the capacitors have 
positive on the can common. Wes.
----- Original Message ----- 
From: "Don" <dontutt at telus.net>
To: "Jukebox mailing list" <jukebox-list at lists.netlojix.com>
Sent: Tuesday, May 01, 2007 1:13 PM
Subject: Re: [Jukebox-list] Selenium Rectifier


> Usually when you see a center tapped secondary winding powering a two 
> diode rectifier you need to watch to see if the center tap also serves as 
> the ground reference.   I think putting a four diode bridge across the 
> whole transformer secondary complicates things.... you get about double 
> the voltage which is not what the loads want.... even if you put a bridge 
> from center tap to one end of the secondary and another bridge from center 
> tap to the other end of the secondary, then tied the bridge outputs 
> together properly you run shorting risks in the bridges when their diodes 
> have extremely small differences in switching times.... ergo they'll run 
> hot even in the best case scenario... even if this would seem to work it 
> seems one risks overheated bridges and also the possiblility that the wire 
> size in the transformer secondary would not be correct for the changed 
> current demand.
> Ron is right, it was engineered for two diodes..... leave good news alone.
> Cheers,
> Don
>
>
> ----- Original Message ----- 
> From: "Ron" <tracron at bigpond.net.au>
> To: "Jukebox mailing list" <jukebox-list at lists.netlojix.com>
> Sent: Tuesday, May 01, 2007 9:13 AM
> Subject: Re: [Jukebox-list] Selenium Rectifier
>
>
>> The two diode design works well, leave it.
>> There is no advantage trying to modify it.
>> May be to high a voltage from the diodes since the selenium rectifier has 
>> been replaced, just check the voltage.
>> 30 volts sounds okay I think it should be around 28V .
>> Ron from OZ
>> ----- Original Message ----- 
>> From: "Jim Poe" <jpoe at dsldata.com>
>> To: "Jukebox mailing list" <jukebox-list at lists.netlojix.com>
>> Sent: Wednesday, May 02, 2007 1:29 AM
>> Subject: Re: [Jukebox-list] Selenium Rectifier
>>
>>
>>> When I was working on my AMI G-200, I was going to replace the diodes in 
>>> the power supply with a bridge.  Got it wired up, & realized I had 60 
>>> volts instead of the required 30.  The transformer has center tap that 
>>> is 30V.  Not being that knowledgeable, I went back to 2 diodes as the 
>>> original design.  Is there a way to get the bridge to work in that 
>>> situation, where the transformer has a center tap & each side is 30V? 
>>> Could I only use 1 side of the transformer?
>>>
>>> Thanks
>>> Jim
>>
>>
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