Pro Audio Design Forum

The 2011-T3 aluminum nuts have about 10X the thermal conductivity of steel or stainless steel. Even more beautiful is that they're about half the cost and in stock. https://img1.fastenal.com/productimages/37708_hr4c.jpg I may wind up being in the low noise matched transistor pair business. Matching...

Do you take bets on a fall before the new year?

Rustic junck. Dust catchers.

No trigonometry in my post.
Here, multiply and divide is good enough for small angles.

You want trig ?
Sin X = Tan X = X
For X small in Radian.
3.14150 Radian is 180°.

You can get a good accuracy with a long plumb line over some flat horizontal base where you can pin marks to see where to it is leaning.
Simple maths gives the angle.
Lean angle is:
180° / 3.14 x side_move / plumb_line_length.

I think, i see the trick. For low noise you need a large base emitter jonction. A large planar transistor seems the answer...then the base would be connected by a metallization ring around the large transistor..then the trouble is from the base thinness. No trouble for outer base emitter junction ar...

I had seen this Matrix geometry but lost it and was unable to find it again. Good, I have it now. Trouble is, I do not understand it well enough. I do know the planar transistor, the manufacturing process, I do know the multiple emittors as found in TTL...But this matrix geometry is something else, ...

Thanks for the news.
I understand the low noise of ZTX851 and ZTX689 comes from it's multiple transistors.
A very interesting technology, can I find more about it ?
How it is implemented. Other transistors of this kind. Are they duals of this kind, is it the same as in LM394 ?

The ZTX689B is a strong contender for mic preamps

Great.
Another interesting point is.
When using 2 x 10K bias base resistors, the high hfe makes it easier on hfe matching.
This is because, hfe mismatch induces a Vb mismatch from ib x Rb.

JR. wrote: ↑Sun Nov 10, 2019 8:28 am

At least the old school (electro-mechanical) thermostat works reliably.

I love the old one with the curved glass tube mercury switch and the coiled bi-metal spring. 1930 clever technology.