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Old 24th March 2013, 03:45 PM   #371
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I was doodling around in LTspice to see if i could make it work without the voltage to current converter on the audio input and the quadruple transistor hysteresis window control circuit.

Now if it will work at all in real life i kinda doubt as im gonna assume choco already tried this prior to adding the transistor circuits, but its still interesting.

Why i did this is that while building the choco version, i found out im all out of some of the transistors and i still wanned something i could get together and play around with until i've ordered more transistors.
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Old 24th March 2013, 06:03 PM   #372
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Disregard this!!! Turns out a a opamp was oscillating, making the circuit clocked rather than self osc.

The LT1115 audio opamp model seem a bit buggy.
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Old 25th March 2013, 01:30 AM   #373
dimitri is offline dimitri  United States
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Hi Markus,

Where this 110-120kHz zero is formed? I couldn't get this extra 30 deg phase lead with my simulations of v1.3

Thank you
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Old 25th March 2013, 06:24 AM   #374
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For me its the opposite, my simulation likes to lock onto a 1.5MHz switching frequency where changing the cap on the comparator inputs does nothing until it get so large the sim slows down to a mere 100kHz.
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Old 25th March 2013, 10:42 PM   #375
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The zero is formed by the two D-portion caps in the feedback.
Means C3 and C4 in the attached sim (respectively C210 and 211 in the real schematic).

I am using the attached way of modelling.
The values are still from the earlier posted version and bode, but V1.3 will not differ fundamentally.
Take care. When simulating large integrating gains you really have to ensure a properly adjusted DC bias situation (already adjusted in the attached file).
Otherwise the sim will just show nonsense of saturated gain stages.

In V1.3 multiple values have changed, also the triangle magnitude is slightly larger. Means the gain of E1 would need to be adjusted slightly.
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Old 25th March 2013, 11:19 PM   #376
dimitri is offline dimitri  United States
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U1 is not inverting, Q2(Q4), E1, E2 are not inverting as well, so the forward path is not inverting?
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Old 26th March 2013, 05:23 PM   #377
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E1 is used inverting. The table numbers are non inverting, and I am feeding the signal into the neg input pin and take the output from the pos output pin.
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Old 27th March 2013, 01:09 AM   #378
dimitri is offline dimitri  United States
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My bad Thank you
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Old 27th March 2013, 02:36 AM   #379
RNMarsh is offline RNMarsh  United States
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In just looking and listening and reading and learning over here.
Hope to try something developed and test it as a 'real' circuit when you get there.

Thx-RNMarsh
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Old 27th March 2013, 06:48 PM   #380
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Hi RNMarsh,
the amp is up and running since about one month.
A short overview of the measured performance of the version of the first builders package (V1.3) is given on page 32 in the postings #316...318.
The proper builders package is ready for download on page 33 posting #329.

Enjoy reading
Markus
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