No, you are not wrong.
Up here in the NE, it's every 2 or 3 poles. I assume it may relate to the local's water table and how low an impedance they present.
jn
Age is a matter of behavior
(unless a coronary or cerebral vascular accident plays infantile party pooper)
Thanks, normally the 6.2 volts isn't enough to break down the junction, but with the added noise cap there may be enough. Of course this probably would not cause the transistor to fail outright, just become noisier which is more of a soft failure and harder to detect.
Since there were a number of useful comments here is my not yet tested design for a mic preamp. Scott won't like the lack of CMRR in the amplifier stages but for external noise the input transformer does the job. The output transformer is an option. In listening tests it was preferred. Although studios tend to like the lower distortion of transformerless designs, field use really is often saved from EMI by transformers. As this design my end up getting used in the field and also far from where it is sending signal two transformers are useful. (Think press conference in a stadium.)
ES
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On high resolution JC-2 pictures i am not able to locate another mosfet cap multiplier, nor on JC -2 schematics you sent earlier.
Yes, it's not the zener voltage that worries so much, but the 220uF dumping through B-E in the event of a hard short, and yes, not likely blowing the transistor up but inducing some significant beta degradation. Having said that the circuit does work rather well given the parts count, though the big Toshirola/Motoshiba (as Cal Perkins used to call them) power transistors are fairly expensive. Specifying them in a couple of power amps a few years ago provoked anguished cries from the overseas vendor.
I like the secondaries' flip for reducing noise.
As they are no longer top of the line the price has dropped a bit. I buy them in a bit of quantity and tend to use them more often than would be justified for a production design. I do like the high flat beta curves.
Now to get things rolling my Bybee just came in!
Stand back!! The Bybees cometh!
Yes, good parts, fast but still pretty rugged, and bless you for saying "flat beta curves" instead of "linear beta". I guess the top of line ones are the somewhat higher breakdown voltage parts, forget the numbers.
When I started work at what a friend described as my "first real job", at Harman Electronics, I inherited the TC600 amplifier which was designed for Harman/Kardon by at least three people preceding me (Hefley, Plunkett, and May). I was assured there was nothing left to be done other than teeny tiny details. Right. It used rows of Toshibas on either side of the fan-cooled heatsink.
What is the inductance of a straight piece of copper wire the same guage as the leads when the contact points are the same distance as you used for the bybee?
For proper tests, you need to autocal out that inductance.
jn
Don't forget to use an externally generated 1/f signal as a control, we need to see the noise and signal differentiated (don't forget to wake up the demon first).
If caught outdoors in open ground in a lightning storm, a person is recommended to squat onto feet only, wrap arms around legs, and (most difficult) keep both feet close together. A few hundred volts foot to foot could kill ya.
One ground good, two grounds bad? Of course some grounds are more equal than others.
Thanks,
Chris
Your recommendation regarding keeping a very small footprint is exact.
A few hundred volts foot to foot probably won't kill you, unless the current has a hard time making that corner...I would not be happy with lots of joules being deposited at the jewels....
It's across the chest that is more lethal. Course, if my jewels got jouled, I probably would have preferred lethal. Kill me now...
If you add a second ground to the system, and the bolt is closer to one than the other, then the entire voltage between the grounding rods will attack any device which connects to both.
jn
.0001 ohms .0002 mH The GR is 4 terminal and seems to be pretty accurate. How it calibrates is something quite simply that hasn't worried me as the numbers seem to be accurate. I used a piece of wire of the same length and gauge as the leads.
Attached is the 1,000 Hz THD W/Noise of the preamp circuit I showed. This is out of the case on the bench. Lower trace is the AP jumped to itself. Upper is through the preamp at full gain. 32K FFT (AP limit) single run.
ES
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Your reported 800 nanohenries is in error by 25%. The real value is 600 according to you.
Your definition of pretty accurate is not the same as mine...shame, shame, shame on you.
Measuring inductance at this level is a beech, ain't it?
Thanks for the numbers.
cheers, jn
You forgot to include the actual inductance of the jumper wire! Do that and you are down to 100 nanohenries ish. So now we can scream about digit bobble in digital displays.
The next item I have up on my bench is a pair of ref mic switches, then measuring an RF injection system, then I can play with the Bybee. Looks like Wednesday.
What jumper wire?
The physical position of the test leads defines the inductance between them. By zeroing via the copper wire, you remove that from the test result. It's the technique needed when testing low impedance cables, where the expected values are in the tens to single digit nanohenries.
Digit bobble?? Are you saying that your trusting and reporting inductance values from the LSD of a meter? Your in the resolution/accuracy mud arena. The numbers aren't trustworthy.
jn
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