I'm not an expert, but ISTR that the masks are fairly complicated multilayer stacks, patterned by e-beam as usual. (The x-rays are softer, i.e. longer wavelength, than the ones they use for looking at your teeth.)
Rapid e-beam would be nice--the price of masks is astronomical, so maybe KLA figures that fabs would rather have 25 ebeam tools than 3 steppers using $5 million mask sets.
Cheers
Phil Hobbs
I think the game here may be to design a low-parts-count amp using discrete parts.
And hardly anybody wants to play the game. Talk, talk, talk, and no circuits.
John
What about this...
Simple headphone amp... view with fixed-width font...
.-2.2u--*----< + 24V regulated | | (must be clean) 220K 47 10W (about 300mA, 500ma at powerup) | | >--2.2u--22K--*-220K--*----470uF----. input | | | (bias) | |--' load (32-100 ohms or so) .--82K--*---||
Is it okay to feed the input into the cathode of the zener?
John
No :-)
The zener is just there to keep static from zapping the gate, not really part of the audio circuit. The input must be R+C coupled to the gate for the negative feedback loop to work.
Terry
Okay, I see. I should have estimated some voltage levels. I now see that the zener is biased below its knee.
Cheers, John
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tKLA is participating in the DARPA nanowriter project if you want to read more about the rapid e-beam.
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Hmmm. I thought that all the common mosfets were lateral. 30 to 40 = years ago Yamaha has some vertical power mosfets but they seem to have pretty much disappeared since. Of course, i am talking about the orientation of the conduction channel, not whether/how the current flows through the = bulk material.
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kI don't get your comment. The current flows in the channel, so how are these cases different? Look at the cross section of a hexfet.
Backwards. Lateral power fets are rare nowadays.
John
Nice little circuit.
The upper 220K could be tuned to null out power supply ripple.
You probably don't need the zener.
John
Thanks :-) but strictly for audiophiles who don't mind consuming 12 watts to produce about a watt output max. Until it gets to clip the distortion products are almost entirely 2nd order (according to LTspice) so it should sound quite "tubey".
I liked your choke-based design... more efficient, cleaner. And bigger! but would have to avoid turning it on with headphones connected (or use time-delay relay or something). Antique Electronic Supply
Hmm didn't think of that... main function is to hard-bias the mosfet to avoid a huge pop when charging the output cap, which is rather large to be fairly flat down to 20hz.
Unless it has external input wires... fet gate spec'd for +/- 10V which might be exceeded by noise/surge input.
Terry
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Read my post more carefully, cowboy.
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