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John Curl's Blowtorch preamplifier part II
John Curl's Blowtorch preamplifier part II
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Old 19th November 2012, 03:54 PM   #29531
PMA is offline PMA  Europe
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John Curl's Blowtorch preamplifier part II
John, what would you think about the added capacitors (parallel to dividers), pl see image.
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Old 19th November 2012, 03:57 PM   #29532
Wavebourn is offline Wavebourn  United States
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John Curl's Blowtorch preamplifier part II
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John, what would you think about the added capacitors (parallel to dividers), pl see image.
I am tempted to mention that they are in series with parasitic capacitances of MOSFETs, that means they are in signal path, and their DA will cause reverberation.

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Old 19th November 2012, 03:59 PM   #29533
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John Curl's Blowtorch preamplifier part II
But they reduce the noise ....
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Old 19th November 2012, 04:03 PM   #29534
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Good idea, PMA.
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Old 19th November 2012, 05:04 PM   #29535
Joshua_G is offline Joshua_G  Israel
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Quote:
Originally Posted by Trevor White View Post
thousands and thousands of posts by the so called guru and not one proposal for a diy project for the benefit of our less learned guests !! The excuses are totally absurd
The CTC Blowtorch was a commercial product, not a DIY project.
John Curl isn't build as to assist amateurs with DIY projects.
John isn't obliged to neither publish any schematic, nor to start a DIY project.
There is lot to be learned from John, even when he doesn't start a DIY project and John readily shares his knowledge, though not complete schematics of some of his designs.
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Old 19th November 2012, 05:48 PM   #29536
Tom Danley is offline Tom Danley  United States
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Hi PMA
A thought;
Since C-6,5,4,1 etc are in series for noise common to both supplies, and individually on each so they form a capacitive Voltage divider also but with somewhat different ratio than the resistors. (Oscilloscope probes often use a Capacitive divider, two different capacitance's instead of two resistors).

If your inclined (or perhaps sitting in your chair haha), try removing C-6 and 5 (7, 8) and place them from ground to the supplies (ala bypass caps in digital, close, place them close to the R15,16 and c1,4 junction..
This leaves the gates referenced to ground (where the output is referenced) and the divider is now a low pass filter to that reference.
Best,
Tom
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Old 19th November 2012, 06:01 PM   #29537
Tom Danley is offline Tom Danley  United States
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nt
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Last edited by Tom Danley; 19th November 2012 at 06:03 PM. Reason: An echo in the machine apparently
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Old 19th November 2012, 06:38 PM   #29538
Nelson Pass is offline Nelson Pass  United States
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John Curl's Blowtorch preamplifier part II
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Originally Posted by PMA View Post
John, what would you think about the added capacitors (parallel to dividers), pl see image.
Without Gate stopper resistors, they are very likely to oscillate.

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Old 19th November 2012, 06:43 PM   #29539
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John Curl's Blowtorch preamplifier part II
That's more than clear
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Old 19th November 2012, 06:47 PM   #29540
Nelson Pass is offline Nelson Pass  United States
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John Curl's Blowtorch preamplifier part II
Does your simulation show it?

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