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Thread: Tube Practice Amp Adding Reverb

  1. #71
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    Quote Originally Posted by g1 View Post
    Note the missing caps coming off the transformer.
    Here's one on the right:

    The one on the right is a quadrupler (two stacked half wave doublers)

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    Quote Originally Posted by g1 View Post
    How is that even a doubler? Looks like standard split supply to me.
    It's a doubler but I think the bottom two diodes of the bridge are redundant. They will always be reverse biased.

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    Last edited by Dave H; 10-29-2019 at 04:52 AM.

  3. #73
    Bent Member Chuck H's Avatar
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    For the record, I did not design the circuit. I just grabbed it with a search. It looked alright to me. I have no idea if Wolf's board requires +/- rails so I played safe. I already have too much time into this thread for the result so maybe I'm getting lazy

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    "In fact when I run into problems working on electronic circuirts, there are so many times that when I finally track it down, the source of the problem is located between my soldering iron and my seat." SoulFetish

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    Quote Originally Posted by g1 View Post
    In Chuck's defense, he said he didn't draw it, that's why I figured it was fair game.
    Note the missing caps coming off the transformer.
    Here's one on the right:

    I guess it's a matter of definition. Getting double the voltage out qualifies it as doubling to me. The figure on the right is actually a quadrupler.

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    Bent Member Chuck H's Avatar
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    I believe the one I posted is actually a sort of dual rail doubler (?) for the +/- rails and just looks very bridge like because the diode junction happens to be convenient with the caps doing double duty for either polarity.?. I'm not as good with power supplies as I probably should be by now, but I think this is what I see.

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    "In fact when I run into problems working on electronic circuirts, there are so many times that when I finally track it down, the source of the problem is located between my soldering iron and my seat." SoulFetish

    "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

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  6. #76
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    Thanks for the schooling fellows. [insert embarrassed emoticon here].

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    Quote Originally Posted by Dave H View Post
    It's a doubler but I think the bottom two diodes of the bridge are redundant. They will always be reverse biased.
    I agree, but think that the circuit posted by Chuck as is has some different benefit/reason.

    First I noticed that if the junction between C1 and C2 were not connected to the rectifier bridge (terminal #4), the circuit would act as a standard bridge rectifier and its DC output would be halved.

    But this also means that the circuit shown provides a simple way to double the DC output of an already existing bridge rectifier supply: Just add 2 caps and one wire (and double the voltage rating of C3). Voila, ecce, eccolo..

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    Last edited by Helmholtz; 11-01-2019 at 04:48 PM.
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    Quote Originally Posted by Helmholtz View Post
    I agree, but think that the circuit posted by Chuck as is has some different benefit/reason.

    First I noticed that if the junction between C1 and C2 were not connected to the rectifier bridge (terminal #4), the circuit would act as a standard bridge rectifier and its DC output would be halved.

    But this also means that the circuit shown provides a simple way to double the DC output of an already existing bridge rectifier supply: Just add 2 caps and one wire (and double the voltage rating of C3). Voila, ecce, eccolo..
    The circuit is a commonly found arrangement dual voltage SMPS front ends.

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    The circuit is a commonly found arrangement dual voltage SMPS front ends.
    Interesting, thanks.

    I guess you mean at the secondary of the flyback transformer? Should be fast switching/recovery diodes then. They probably use integrated bridges, not discrete diodes, right?

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    Last edited by Helmholtz; 11-01-2019 at 06:33 PM.
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    I've seen it directly on the mains input for 115/230V selection.

    Click image for larger version. 

Name:	SMPS 115-230V.png 
Views:	19 
Size:	50.2 KB 
ID:	55837

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    Last edited by Dave H; 11-01-2019 at 06:32 PM. Reason: Added schematic

  11. #81
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    Quote Originally Posted by Dave H View Post
    I've seen it directly on the mains input for 115/230V selection.

    Click image for larger version. 

Name:	SMPS 115-230V.png 
Views:	19 
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ID:	55837
    Makes a lot of sense. In this application you actually need all 4 diodes to switch between both modes.

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