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Old 30th November 2010, 12:52 PM   #81
Ivey is offline Ivey  United States
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Default Good Stuff Salas

I copied it, and I love what I saw. It remained me of JLH's stuff. In any event, it looks like a good build.

I have all of these cool transistors that I pulled from de-funked equipment. Mostly old automakers engine test stands and monitors. Lots and lots of transistors from the early 1960's. And I have all of these BC558C and BC548C at I got out of Amana 1970's microwave oven control units.

So this is what I am going to do. I will replace the 2N4401's with PN3566's. Replace the BC139 with a 2N4919, and use the BC548C/558C's in place of the BC550/560's.

How does that sound?


Take Care

Ivey
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Last edited by Ivey; 30th November 2010 at 12:54 PM.
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Old 30th November 2010, 01:03 PM   #82
Salas is offline Salas  Greece
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Sounds like a noisier and much slower scenario. Use 2N5086/87/88/89 & MJE340 for an all American build. Match hFE in the quintet.
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Old 30th November 2010, 02:06 PM   #83
Ivey is offline Ivey  United States
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Default Alexf

I understand completely. There's no foul. Just give me your first born grand child and all is o.k..

No..., Its just a joke. I got too many grandchildren as it is. 9 all together, and the holidays are just weeks away. And my wife (bless her sweet heart) is shopping daily.

So please.., NO more kids.

Alexf, most people do not have, nor they know fully, how the read and understand the spec's on most transistors, resistors, capacitors and other components.

Most people (me included) use to go by what others understood, told me, and thought that they had an understanding of. It was not until I went to Sprauge and SGS, did I get an education on reading data sheets.

I am looking at my old Sprague Wafer process data book CN2501-2C. It is filled section on 61 different transistor processes.

I slice open many transistors in my shop with my 4000 psi mini water jet cutter. And I view the wafer in side of a batch of TO92B, D, or even H's. And I get a good idea of what I have on hand.

The science is so much fun for me, that I have to know what I got. Just having them is not enough. Also, I love to cut sheet metal and wood with my water jet cutter. And as soon as this factory up in Long Beach closes, I am getting their mini mold press for $3000.00. I have already got the used computer for it. And it only cost $100.00 dollars. Fools, their all fools. But good ones.

Any way, I do not care for beta doping of wafers. Its kind of unnatural to me. I was told by an engineer at Sprauge, that if you can not build a good solid one piece wafer without doping. It much like cheating.

The BC546 is a good BBC process. It is pure. The wafer is cut just right to get that basic gain and current and voltage. But A, B, C, are the doping process of the BBC process to get better gain and quicker switching. Its all good, but I like the natural basic wafer cut.

It is much like Intel, when they put too many transistors into one chip. The wafer gets thinner and thinner. One wrong move. And..., bang. There goes your quad core cpu and hundreds of dollars.

The BC550 is an outstanding transistor. Its noise factor of 2-4db is excellent. Its gain is mouth watering. But it is locked in at 55 volts. Its true max. voltage.

The 2N2222A's true max voltage for its single cut wafer is 75 volts in TO18 and 55 volts in TO92D.

Lets look at switching and compare the rise and fall times of the two wafer processes.

The DCA process (2N2222A) rise time is 12-25ns, fall time is 24-60ns. Now the BBC process (BC550/546) rise time is 16-25ns, fall time is 50-80ns. So which one do you want to use with your new super fast cpu?

When you want that circuit clamped. You want it clamped.

You do not want trailing edges on the square waves. And this is very important in digital music.

So when I have to use a transistor, and do not have the time to over spec's. I grab a 2N2222A. And then I only have to worry about R and C.

The gain figures are very misleading if you do not have the data manuals that I do. The gain on a 2N2222A is typical at 150 at 1 volt @ 100ua. There is no min. and no max.. 2N2222A, gain is 50 to 600 at 1 volt @ 10ma. The BC546 gain is much lower by compare. Which is 5 volts @ 100ua for a typical gain of 140. 4 volts greater.

If you are confused on the term doping, I will explain. The BBC process starts out as a DCA (2N2222A). It is then alternate to a JGA (MPSA06), then finally a TNL (2N5376) completes the process. So wafer has these cuts or molded processes done to it. Where you lose and gain in each process/cut or mold.

That is why you require those 4 extra volts, in order to get the results that you do from the BBC process. Because you need force (volts) to push the carriers along the wafer. In the DCA prcocess, which is pure, you only require 1 volt.

Take Care

Ivey
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Old 30th November 2010, 03:02 PM   #84
Ivey is offline Ivey  United States
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Default USA USA USA

Do not get mad at me Salas. I can not help it if we invented the Transistors and went on to perfect it. And built the first IC chip, landed the first man on the moon, and explor Mars; sent space vessels to far and distance planets. Oh, and I mention, putting the first telescope in space.

But look, what Greece have done for us all. The have given us Zeus, Troy, Homer, Sparta. And a host of wonderful and tasty foods. Not to mention, a rich history in life itself.

It is just that I have all of these transistors, with such a clear loving history of use and design. And if it was not for customs, I would love to share them with you.

For a Gyro of course. Nice an hot, with sour cream and french fries, and big coke a cola.

Take Care

Ivey
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Old 30th November 2010, 04:02 PM   #85
Salas is offline Salas  Greece
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Those alternative BJTs I suggested are American but better suitable for that design. 2N4919 you wanted to use is 3MHz Ft and BC548 is 10dB NF, PN3566 is 25pF Cob'. Not good to parallel. Avoid.
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Old 30th November 2010, 08:32 PM   #86
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Quote:
Originally Posted by Ivey View Post
The BC550 is an outstanding transistor. Its noise factor of 2-4db is excellent. Its gain is mouth watering. But it is locked in at 55 volts. Its true max. voltage.

The 2N2222A's true max voltage for its single cut wafer is 75 volts in TO18 and 55 volts in TO92D.

Lets look at switching and compare the rise and fall times of the two wafer processes.
Did I ever say that BC550 is better for switching?
I use the 2n2222 or rather MMBT2222A these days for just about everything that switches. It's the audio applications and low level input stages that I'm talking about.
I'm no expert in audio. And maybe I can't read the data sheets. But I came across quite a few circuits using the BC550 and friends and use it in some audio circuits with great results.
You keep mentioning the VCE, but what difference does it make for a pre-amp powered from 30V if VCE is 55 or 75?

And don't tell me I'm not patriotic I get my BC550s from ON Semi right here in the Silicon Valley
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Old 30th November 2010, 11:52 PM   #87
Ivey is offline Ivey  United States
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Alef: if you are getting the impression that I am insulting your education, then I must regress. For it was not my purpose or intention.

Salas has stated that the 2N4919's ft is 3Mhz, which is more than 20 times the freq. in question. So even thou the 2N4919 comes no where near the ft of the BC139. It still has a good ft for my audio needs. The BC550 is a great performer in any circuit you choose to use it in. It does have a very good noise rating. But here is the position I take.

I know that the 2N2222A's gain is lousy pass 25ma's and it starts to drop off as you push more carries through it. But between 100ua and 17ma's, it is hell on wheels.

So between 100ua and 10ma, the gain is 150 to 600. That is the range of operation that I will focus on.

Plus the fact that I can obtain it with 1-5 volts, will only aid me in designing a circuit scheme around the circuit values that Salas has provided me.

The add plus side is that the 2N2222A db factor is 0-4db. is also helpful.

Vce is an important factor in designing with transistors. It enable you to use the good points of the unit in question.

In push-pull line driver circuits 2N2222A can drive small step motors up to 500mw. Or 800mw if heat sink. In audio circuit I can use a higher voltage if need be and less current to move the carriers.

But Salas was correct; the BC548's noise factor is not so good, ranging from 2 to 10db. But I just got to get some use out of all these used transistors I have on hand, on top of all the new ones as well.
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Last edited by Ivey; 30th November 2010 at 11:56 PM.
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Old 2nd December 2010, 08:34 AM   #88
Ivey is offline Ivey  United States
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Default PCB for Salas's MC Phono

Salas, I laid out your wonderful MC Phono design in Quick Route software (my favorite). Later I will transfer the design to Express PCB, since most people do not have Quick Route any longer.

Can I ask if you bread boarded your design and tested it. If not I will do so with a perf board and test it for all of us.

So, my friend just let me know your status on this issue.

Oh yes, my transistor choices are not set in stone. I may just change up on most of the chips. Since I did all of my work with US Defense Contractors, my stash of transistors are mainly US stock. I do have PRO Electron and JN's, about 1500 of both, in various types. But they are mainly transistors used in electronic controllers, tv monitors, interface converters, and data movers; when I upgraded NATO equipment.



Take Care

Ivey
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Last edited by Ivey; 2nd December 2010 at 08:37 AM.
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Old 2nd December 2010, 11:07 AM   #89
Salas is offline Salas  Greece
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No I haven't breadboarded it. Its a reforming idea of a classic that surely worked in many units but the changes are also many and key, so it needs to be checked beyond simulation. Especially when you have even more transistor types in mind. There are two feedback loops and you got to see its stable as a whole. Its other characteristics are much more predictable. I highly recommend you run a practical check before ordering a PCB. Use lowest noise matched hFE for the front end NPN quintet (Q1-Q5). It runs 110uA each, has 17.5V across them. Q7 has 10V across and 60mA. Use TO-126 and a small clip-on sink. I expect bias to be near enough those numbers with the originally specified BJTs or satisfactorily similar. C2,C4 1% if it will be a final build. C3 plays a role in LF teaming with C1, must be good quality and 220uF nominal +/-10%. C1 must stay around 3uF. Good luck.
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Old 2nd December 2010, 04:05 PM   #90
Ivey is offline Ivey  United States
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OK Salas, this is what I will do.

My grandson and I, will breadboard the unit.

I will use 2N5088 in the front end.

2N3904/6 for all the others. That transistor has a max. db factor of 4.5. Max.!

And I will use a BC139-16.

Metal film polyesters @ 10%. Use polypro's in the final build.

So what do you think of that?

Take Care

Ivey
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