Search found 120 matches

by terkio
Sun Nov 17, 2019 1:30 pm
Forum: Pro Audio Design
Topic: Low Noise Transistors: ZTX851 versus ZTX689B Noise Performance
Replies: 8
Views: 128

Re: Low Noise Transistors: ZTX851 versus ZTX689B Noise Performance

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...
by terkio
Sun Nov 17, 2019 8:06 am
Forum: Pro Audio Design
Topic: Low Noise Transistors: ZTX851 versus ZTX689B Noise Performance
Replies: 8
Views: 128

Re: Low Noise Transistors: ZTX851 versus ZTX689B Noise Performance

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, ...
by terkio
Sat Nov 16, 2019 10:57 pm
Forum: Pro Audio Design
Topic: Low Noise Transistors: ZTX851 versus ZTX689B Noise Performance
Replies: 8
Views: 128

Re: Low Noise Transistors: ZTX851 versus ZTX689B Noise Performance

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 ?
by terkio
Fri Nov 15, 2019 8:20 pm
Forum: Pro Audio Design
Topic: A Low Noise Balanced Input Moving Coil Preamp Using the ZTX851
Replies: 495
Views: 202019

Re: A Low Noise Balanced Input Moving Coil Preamp Using the ZTX851

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.
by terkio
Sun Nov 10, 2019 10:36 am
Forum: The Peabody Lounge
Topic: home improvement turns into science fair projects?
Replies: 83
Views: 4710

Re: home improvement turns into science fair projects?

JR. wrote:
Sun Nov 10, 2019 9:28 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.
by terkio
Sat Nov 09, 2019 4:43 pm
Forum: The Peabody Lounge
Topic: home improvement turns into science fair projects?
Replies: 83
Views: 4710

Re: home improvement turns into science fair projects?

We've started installing USB wall outlets here. The Levitons have two USB ports and two NEMA outlets. The USB is 15W. I would love to have a bunch of adapters that would take 5V USB from the outlets and give me switchable 6, 9 and 12V to replace conventional magnetic wall warts. Do you mean you are...
by terkio
Sat Nov 09, 2019 3:13 pm
Forum: The Peabody Lounge
Topic: home improvement turns into science fair projects?
Replies: 83
Views: 4710

Re: home improvement turns into science fair projects?

JR. wrote:
Sat Nov 09, 2019 2:39 pm
The grow lights are secured to the green house shelves so I can't just drag them inside to a computer USB.
Perhaps you can bring a Notebook or Tablet PC to them.
by terkio
Wed Nov 06, 2019 9:57 pm
Forum: The Peabody Lounge
Topic: UK: National Health Service to Deny Treatment for ‘Racist or Sexist Language, Gestures, Behaviour’
Replies: 9
Views: 239

Re: UK: National Health Service to Deny Treatment for ‘Racist or Sexist Language, Gestures, Behaviour’

Are you aware of insults and violences in Europe at hospitals and schools that are becoming more and more unacceptable ?
These are mostly ethnic and political religion troubles.
by terkio
Sun Nov 03, 2019 2:58 pm
Forum: Document
Topic: Vintage Digital Clock Circuits
Replies: 9
Views: 11580

Re: Vintage Digital Clock Circuits

Like this thingy from Garmin: https://www.proaudiodesignforum.com/forum/php/viewtopic.php?f=15&t=1068 Same look. High tech @ $30. USB. ( Serial over USB, so using a driver giving a virtual serial port ). I played making my own GPS system using this receiver with a marine navigation software and map...
by terkio
Sun Nov 03, 2019 12:47 pm
Forum: Document
Topic: Vintage Digital Clock Circuits
Replies: 9
Views: 11580

Re: Vintage Digital Clock Circuits

In case you need the accuracy of the best atomic clocks.

Use a GPS receiver.
It's embedded SIRF chip gives the time, in the stream of data given on a serial port.

10^ -13 accuracy.