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Inside op-amps
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Graham Slee View Drop Down
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Points: 16298 		Post Options Post Options   Thanks (1) Thanks(1)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 07 Aug 2022 at 6:24am
Regarding the "which way up?" comment on my last diagram, it depends on whether the op-amp input is NPN, PNP, N-channel or P-channel.

If it is NPN or N-channel, current flows inward so there is a voltage drop across the input resistor, and so the input is negative to the 0V mid-rail. As both inputs are made identical by op-amp law, then the capacitor shown is wrong way up.

If it is PNP or P-channel, current flows outward so there is a voltage rise across the input resistor, and so the input is positive to the 0V mid-rail. As both inputs are made identical by op-amp law, then the capacitor shown is right way up.

The amount of voltage drop or voltage rise depends on the input bias current and the input resistance (by Ohm's law).

An electrolytic capacitor is a polarised device and is marked as such. Values as high as 1000uF have featured in at least one RIAA stage I have seen.

Initial leakage is 0.01Q + 3(uA) for most sub 100V electrolytics.

The initial leakage adds to the charge time constant, extending the time it takes to charge the capacitor.

I'm not going into the cumbersome maths here, but I'd be surprised if the capacitor's leakage will be overcome in a single listening session!

Now, if it had a decent voltage across it?

The single rail application provides that "decent voltage".

And then, if an "op-amp roller" replaces the op-amp from NPN or N-channel to a PNP or P-channel (or vice versa), then what?

I'm sure there'll be a difference in how it sounds...
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Graham Slee View Drop Down
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Points: 16298 		Post Options Post Options   Thanks (1) Thanks(1)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 08 Aug 2022 at 6:50am
Long ago, 50 years ago, there was a thirst for knowledge like this. Quite a lot of people were thankful for it.

Today, DIY is dead.
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Fatmangolf View Drop Down
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Points: 8989 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Fatmangolf Quote  Post ReplyReply Direct Link To This Post Posted: 08 Aug 2022 at 7:41am
Originally posted by Graham Slee Graham Slee wrote:

Long ago, 50 years ago, there was a thirst for knowledge like this. Quite a lot of people were thankful for it.

Today, DIY is dead.

Thank you again for this information. Why do you think DIY is dead, please?
Jon

Open mind and ears whilst owning GSP Genera, Accession M, Accession MC, Elevator EXP, Solo ULDE, Proprius amps, Cusat50 cables, Lautus digital cable, Spatia cables and links, and a Majestic DAC.
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gwebster View Drop Down
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Points: 175 		Post Options Post Options   Thanks (0) Thanks(0)   Quote gwebster Quote  Post ReplyReply Direct Link To This Post Posted: 08 Aug 2022 at 10:52am
Originally posted by Graham Slee Graham Slee wrote:

Long ago, 50 years ago, there was a thirst for knowledge like this. Quite a lot of people were thankful for it.

Today, DIY is dead.
I'm still doing lots of DIY electronics. While my current audio setup includes my Bitzie DAC paired with a Raspberry Pi, a commercial CD player and FM tuner, the phono (replacing my Genera phono), pre-amp, digital remote controller and power amp are all strictly DIY.
I've been avidly following this thread and have been making use of the formulae to verify elements of my phono circuit based on Graham's patented phono architecture (patent stuff is OK to apply to personal use but not for commercial without paying a license fee, I understand).
Inspire Apollo tt, O/L modded RB250, Ortofon 2M Black, Slee Different Approach inspired Phono, Putzeys Pre, Cusat, Raspberry Pi/Volumio, Bitzie, Self Load Invariant Power, Acoustic Energy AE509s
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Graham Slee View Drop Down
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Points: 16298 		Post Options Post Options   Thanks (1) Thanks(1)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 09 Aug 2022 at 7:23am
Perhaps it's the way I tell 'em... Wink

But I don't think there's anything like the clamour for learning from the ground up. Half way through the movie perhaps, but not the fundamentals. By half way through the movie, I mean, taking an existing item and playing about with it.

OK, there may be nothing wrong with that. I guess it could be something to do with my age and my frugal upbringing. Starting out at zero seems to be dead, as in not interesting.

I do see a few members here having a read - probably two, three, or maybe up to five. It's indicated in brackets after the main forum title, but it could be any of its topics, maybe not this one.

We used to have members who wanted more DIY, so I offered what I could, and I haven't seen them since! (many years in-fact) Perhaps it's the wrong DIY? I can only try and share what I know, and what I know has led to the things folks buy from us, and they seem popular enough.

I must admit to being an analogue man, and I know this is a digital world (cue for a song?), so maybe that's why I feel very few have any interest?

By dead, I mean dead in spirit (enthusiasm).
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Graham Slee View Drop Down
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Points: 16298 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 09 Aug 2022 at 7:38am
Originally posted by gwebster gwebster wrote:

(patent stuff is OK to apply to personal use but not for commercial without paying a license fee, I understand).

Correct!

And it is encouraged - the personal use part (that's the spirit of invention/discovery/whatever).

It's all part of the learning spiral, and as we ascend that staircase we come back around and start seeing things a little differently, and maybe through the lessons we learn, we can make it a little better each time.

How many widgets lay at rest in coffins? What benefit did those widgets bring to anyone?
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Fatmangolf View Drop Down
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Points: 8989 		Post Options Post Options   Thanks (1) Thanks(1)   Quote Fatmangolf Quote  Post ReplyReply Direct Link To This Post Posted: 09 Aug 2022 at 7:38am
Yes I see your point about fewer people building from scratch as compared to modifications, thanks Graham.
Jon

Open mind and ears whilst owning GSP Genera, Accession M, Accession MC, Elevator EXP, Solo ULDE, Proprius amps, Cusat50 cables, Lautus digital cable, Spatia cables and links, and a Majestic DAC.
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