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  #1  
Old 16th August 2019, 04:57 PM
saracenblue saracenblue is offline
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Location: Redruth, Cornwall
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Default Triode/Ultra linear switch

I'm hoping to fit a Triode/UL switch to my EL84 SE amplifier.
There is a lot of information online about mode switches but not many diagrams. As I find diagrams easier to understand I have sketched up what I think may be suitable in the hope that a member would please take a look and advise as necessary.



Thanks
Graham
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  #2  
Old 17th August 2019, 07:01 AM
snowman_al snowman_al is offline
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Default Re: Triode/Ultra linear switch

That is fine.
I suspect you have not drawn the switch correctly though, you do not need (or want) the middle 'open' position.
Alan
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Old 17th August 2019, 09:19 AM
saracenblue saracenblue is offline
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Default Re: Triode/Ultra linear switch

Thanks for your response Snowman Al,
I see what you mean about the switch, I've drawn it wrongly. I intend to have a simple On-On switch as I realise that all switching must be done with the amp powered down.
I was concerned about the resistor positioning and its' value but now I shall now proceed and order the parts.
Graham
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  #4  
Old 17th August 2019, 04:23 PM
John Caswell John Caswell is offline
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Default Re: Triode/Ultra linear switch

Hi Graham,
As Alan says you do not need a 3way switch, however it does need to be close to the anode/screen grid connections of the valve and NOT on the front/back panel with long leads. That way lies trouble.
The 100R is fine and once again as close to the valve as possible.
If you want it to be a bit more elegant then you could use a relay instead of the switch, and then the switch could be where you like.

John
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  #5  
Old 17th August 2019, 06:58 PM
saracenblue saracenblue is offline
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Default Re: Triode/Ultra linear switch

Hi John,
Many thanks for the advice. The amp is constructed on a PCB and I have a location in mind for the switch, which is adjacent to the PCB connector that houses the wires leading to the output transformers. There is a little space there and my revised wiring should be minimal.
Your assistance is appreciated.
Graham
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