MJL 21194G - plastic (tested in the prototype)
MJ 21194G - TO-3 to be used in final build
It's the same thing, just different case.
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I tested the following op-amps with my build of Circlophone:
Yes: LT1056
Yes: TLE2071
Yes: TLE2081
Yes: TL071
Yes: LF356
Yes: AD711
Nope: OPA132
Nope: LT1357
Also, output DC offset is literally 0mV, measured with multimeter that supposedly has precision 0.01mV.
Yes: LT1056
Yes: TLE2071
Yes: TLE2081
Yes: TL071
Yes: LF356
Yes: AD711
Nope: OPA132
Nope: LT1357
Also, output DC offset is literally 0mV, measured with multimeter that supposedly has precision 0.01mV.
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One thing I noticed, the current via Red LED (D1) is only 0.5mA, so the LED is not lite. It's dark.
Everything seems to work fine, but I wonder if it's OK to keep LED in there, or perhaps replace it
with 2 or 3 regular diodes, just like in original circlophone?
I didn't notice during simulations that that current is so low...
I just checked how was this current in the original circlo, and it was even lower (120uA).
Not sure if it matters - LED vs 3 x 1N914, perhaps it doesn't, but it looks silly - a LED that doesn't emit light 🙂
2nd Channel is up and running, so now mechanical work ahead of me. Drilling, tapping, machining, polishing..
Everything seems to work fine, but I wonder if it's OK to keep LED in there, or perhaps replace it
with 2 or 3 regular diodes, just like in original circlophone?
I didn't notice during simulations that that current is so low...
I just checked how was this current in the original circlo, and it was even lower (120uA).
Not sure if it matters - LED vs 3 x 1N914, perhaps it doesn't, but it looks silly - a LED that doesn't emit light 🙂
2nd Channel is up and running, so now mechanical work ahead of me. Drilling, tapping, machining, polishing..
The main purpose of the LED is to keep the "vertical" servo loop within reasonable limits, not to be part of Christmas illuminations.
If you want it anyway, modern LEDs exist that can almost blind you with 100µA....
If you want it anyway, modern LEDs exist that can almost blind you with 100µA....
Drilling, taping and the mock-up of the chassis.
Alu slab 9 x 10 x 1 inch
Alu slab 9 x 10 x 1 inch
Holy smokes MineK. That right there is a chunk of Aluminum.
Hi Bangla H,
I can't read your schematic (low definition image) and open your gerber files with Gerbview).
Maybe you can post good definition image of your schematic, and pdf or jpeg file of the pcb?
Thanks.
I have sad news to share on this tread, @katiyar is no more, he passed away thursday, may his soul rest in peace and god give strenght to his family through these tough times.
Sorry if this has already been answered 10 times in the thread.
But what contributed to the "class A sound"?
Is it the lack of emitter degeneration in the output? low output impedance?
But what contributed to the "class A sound"?
Is it the lack of emitter degeneration in the output? low output impedance?
Mainly the fact that both output devices are always active, and in control.
Some non-switching schemes simply use a "dumb" CCS to keep the inactive side alive, but in practice that's no better than standard class AB.
The Circlo engine keeps both devices under control, all of the time
Some non-switching schemes simply use a "dumb" CCS to keep the inactive side alive, but in practice that's no better than standard class AB.
The Circlo engine keeps both devices under control, all of the time
Sorry and so sad to here/ready that a good fellow here has gone.
RIP and All the best wishes for Family Members
Best Regards.
RIP and All the best wishes for Family Members
Best Regards.
Hi, I see a lot of simulation diagrams here with THD values, FFT's and Bode diagrams. Who uses Nyquist diagrams to see if your amplifiers stays stable even in the Mhz regions?
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^Hi,
How to plot the above graph? and what does it says? Can you share an .asc file as an example?
Thanks!
How to plot the above graph? and what does it says? Can you share an .asc file as an example?
Thanks!
Some theory about stability at this link and this link.
When you do an AC analysis of your circuit e.g. ".ac dec 100 10 10e6" the standard plot is a bode plot. When you right click in the left margin of the plot, you can choose a representation from a list. Choose the Nyquist, that's all. Maybe you have to resize your window to get the picture right or change the X/Y-axe max values.
You can use any of the LTSpice circuit .asc files from this thread.
EDIT: added link and corrected typos.
When you do an AC analysis of your circuit e.g. ".ac dec 100 10 10e6" the standard plot is a bode plot. When you right click in the left margin of the plot, you can choose a representation from a list. Choose the Nyquist, that's all. Maybe you have to resize your window to get the picture right or change the X/Y-axe max values.
You can use any of the LTSpice circuit .asc files from this thread.
EDIT: added link and corrected typos.
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My op-amp based Circlophone is officially completed.
Plugged it on this morning, and it's playing music right now. I compared the sound with the original Circlophone, and:
a) they sound the almost same (but that's true for most of amps..)
b) new one is also dead quiet when idle (no noise, no hum, etc..)
c) as far as I can tell, the sound has slightly more more bass
d) DC output offset is 0.3mV
Schematic as in post #2486 and PCB from post #2504.
It's currently running with 40V rails (maybe slightly less under load).
Under normal listening conditions, this bulky aluminum chassis (1 inch thick slab + heat sinks) is maybe 1-2 degrees above room temperature,
output transistors barely warm.
Plugged it on this morning, and it's playing music right now. I compared the sound with the original Circlophone, and:
a) they sound the almost same (but that's true for most of amps..)
b) new one is also dead quiet when idle (no noise, no hum, etc..)
c) as far as I can tell, the sound has slightly more more bass
d) DC output offset is 0.3mV
Schematic as in post #2486 and PCB from post #2504.
It's currently running with 40V rails (maybe slightly less under load).
Under normal listening conditions, this bulky aluminum chassis (1 inch thick slab + heat sinks) is maybe 1-2 degrees above room temperature,
output transistors barely warm.