Hello John,
Yes, and that is part of many of the sermons. We have a group of missionaries going to Russia tomorrow morning. They don't have their tickets yet, none speaks Russian.... but they trust it's going to work out ok.
Regards, Joerg
Hello Winfield,
When a friend was speaking I saw the field strength meter on the wireless receiver for his mike go from near full scale to zilch. Oh no, not now... The battery had given out. He has such a thunderous voice that I could not notice a difference and I was way in the back, behind the audience.
So it may just be a matter of training ;-)
Regards, Joerg
Hello Jim,
My experience is limited to their 9V wireless gear which I would not recommend because of limited battery life and premature battery failures. There is a new "SK 100 G2" unit which looks very interesting and that is the one I am going to check out once we upgrade:
The corresponding receivers are typically 19" rack mount and I believe they do sell kits that contain transmitter, mike, receiver, diversity antennas, power supply and the cables. The Sennheiser web site is not very good so you may have to call them to see what the best deal would be for the whole set. Believe it or not, their "search function" didn't find their own SK100 mike transmitters, Google did...
Since this is professional gear the output is usually differential, for connection to a large mixer panel.
To be honest, this professional gear takes more time to set up in the field when compared to cheaper systems like the Radio Shack I mentioned before.
My only gripe besides the 9V with our existing Sennheisers is the pop noise upon turn-off and mute. But if your wife's scout presentations are typically uninterrupted that won't matter. Also, these systems can be upgraded to umpteen mikes if that was ever needed.
Regards, Joerg
I misled myself I'm afraid. It's that long ago that I forget the exact details.
Graham
Especially considering he was explaining why beta matching is important !
Graham
I'm curious why you'd send missionaries to Russia. They already have the Orthodox Church there which is making something of a comeback after decades of communism ( although it never ever truly died out ).
Have your missionaries previously met the Russian Mafia btw ? ;-)
Graham
Hello Mike,
We had sent them in a while ago. The frequency info losses aren't really a big concern, battery life is the problem. Also, we have four mikes/receivers so that waters down the statistical significance of the memory failure events.
The mute buttons are a bit weak, too. We had one croak and another become rickety. The handhelds have better quality mute buttons but they are hard to operate because you have to turn a cover wheel and then fumble around behind the mike to find it. So we usually just turn the mike away from the pulpit after the scripture readings (our pastor wears a lapel mike).
Regards, Joerg
Hello Graham,
From what I know there was a school principal from Petrozavodsk who visited a Christian school in the US. This was AFAIK back in the commie times and he was not so much interested in the bible (I guess his gvt didn't like that at all) but in why students were better motivated, among other things, and what he could do about that back in Russia. That is where the idea came up to send people over from here to teach the students in Russia English, using the bible as a text book. So, now there are regular missions to that city, not just from our church but also lots of others.
Participation is voluntary for students. Usually 100-200 sign up from what I heard. This year blew us away, a whopping 1000 signed up.
No, but I guess they wouldn't be interested much in missionaries.
Regards, Joerg
Hello Jim,
A lot of things in our country rely on generosity and that is good. It shows the next generation where the real values are.
Once you buy a system maybe your wife could train a few girl scouts to become the "technology team". Then they can set it all up and learn how stuff like a wireless system works. And what to do when it doesn't. What was that motto? "Be prepared". So they could check for free UHF channels at the planned location, figure out the frequency, make sure all the gear is packed and so on.
Regards, Joerg
Lol ! Nothing wrong with that Jim !
I just imagined that the Scouts don't normally have a great budget for tech stuff. I've helped out the UK Scouts in the past btw. They're damn fine with ropes and had my PA rig mounted on scaffolding towers in no time at all !
Graham
Due to poorer design of driver stages. Parts cost more back then and it wasn't normal practice to 'overdesign'.
There's still quite a big spread in hfe. Better design of the driver stage eliminates the problem.
Graham
But Kevin is right, Ebers-Moll is defined via Vbe and Vbc. And beta_f or beta_r are only derived from the alpha terms. I think it is just a point of view, in practical circuits you use hfe and don't care much for Vbe since it is almost constant in comparison to the current.
-- ciao Ban Bordighera, Italy
Most of us know how to design a simple bipolar transistor stage using the current model. The design equations and explanations need just a few rows of text.
How would you design the same transistor stage using the voltage-controlled model?
Can you show us how your way is faster, better, etc..?
How does it work in real transistor stage design?
-- Roger J.
Its not just the Ebers-Moll, its the *device* *physics*. Its how a transistor actually works from a phyiscal point of view. There is simply no way that flow of base charge induces a flow of collector charge.
If one don't understand that it is Vbe that determines and injects carries into the base that are then swept up into the collector, then one doesn't understand transistor operation at all. Its that simple.
No it isnt.
This is simply not true. The only practical way to effectivly design transister amplifiers is to treat the transistor as a voltage controlled current source. Period. e.g.
di = dv.gm
Av max = Va/Vt etc.
Kevin Aylward snipped-for-privacy@anasoft.co.uk
Indeed. The explanation was why hfe matching mattered despite the fact that the bipolar transistor is a voltage controlled device. To wit, its the voltage drop across rbb' that is the killer.
Why don't you use spice and put two power transistors in parallel. Have two separate models, with only Bf different. Do runs with and without RB set to zero. Then put in emitter resisters. Its a good exercise.
Kevin Aylward snipped-for-privacy@anasoft.co.uk
Indeed. It is they way they work. Only the illinformed consider that the transister is current controlled.
What we have here is an enormous amount of erroneous waffle on the bipolar transistor. Its quite amazing really. There is no point in perpetuating this daft myth. It only leads to confusion.
Any *actual* *understanding* of the standard 3 junction pictorial descriptions of basic transistor operation should leave people with no doubt as to the correct operation of a bipolar transistor. Base current don't "cause" the flow of collector/emitter current. Its Vbe that injects charge into the emitter, irrespective of base current. End of story.
Kevin Aylward snipped-for-privacy@anasoft.co.uk
BOB URZ"
Actually I had forgotten that it was Tom Lehrer. I should have remembered since he was a performer at the junior prom at MIT in 1961, along with, IIRC, my memory is fuzzy here... Jenny Richie ??
...Jim Thompson
--
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I love to cook with wine. Sometimes I even put it in the food.
Ah.
Thanks, Rich
Tastes Great!
Less Filling!
-- Cheers! Rich ------ "There was a young lady of fashion Who had oodles and oodles of passion. To her lover she said, As they climbed into bed, "Here\'s one thing the bastards can\'t ration!""
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