I think i understand the basics of the calculations, but it would be nice to understand why the parts are needed. Which parts? Are we discussing the common emitter circuit?I also dont like the guessing part of the calculation, it seems to me that the part will likely behave about the same under similar conditions for most people. It's not a "guess". You have to start somewhere. Having only the least is a good start, if there's more (as in more beta, as may be likely) then it only gets better. The circuit will not be a worse performer for the transistor's having more beta (gain) than anticipated.It seems like it should be easy to look that up in a chart or graph, and get close with your calculations, but I wasnt able to do that, I had to test things, before I could get in the ballpark.How can I know where you're losing the plot? You haven't shown your work.I can't see what's going on in your schematics; they're pretty free-form, difficult to follow.
In the past I've done calculations, and later found out that real world numbers and calculations can be very different, its best to test things with the specific parts, and specific power supplies, because they can vary.
I still dont have any idea how to figure out how to figure out the gain/hfe/beta for the calculations,
It seems to me, that should be as simple as looking it up in a table on the datasheet.
The beta numbers 10 and 100 came from 2 different individuals, when I asked them where on the datasheet can I find the right value for my uses (20-240ma at 5v).
It seems to me, that there should be a few common resistors used with 2n2222 transistors, one for 5v, and other for 12v applications. the part is only good for about 1/2 amp (mine are smt, and only good for 350ma). I would think that I would find 5v circuits all had about the same value base resistor, and 12v circuits would have a different value, but the 12v circuits would all have a similar value base resistor.
I dont really see any value in the posts after I posted my calculations.
I am curious about the claims of vitriol though, but whatever, its probably not important.
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