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audioguru said:WalMart had a fading LED globe with 3 colors of LEDs. It used a microcontroller and you could see the fading jerk between the steps.
My analog fading 3 colors of LEDs fade smoothly.
audioguru said:An astable multivibrator using silicon transistors harms the transistors if the supply voltage is more than about 6V which is the absolute max allowed voltage for the reverse emitter-base voltage for a silicon transistor. The emitter-base junctions have avalanche breakdown.
Here's a quote from Bob Pease:saturn1bguy said:Howdy,
What you say above is interesting, theoretically, certainly. After having
looked at URL you referenced, I can see what you're talking about.
Empirically, however, I have found that the above theory has never
caused an issue in any of *many* copies of that exact circuit I've built
over the years. Mostly I stick them in cars in/near the dash somewhere
to discourage people from tampering (they see red LEDs flashing back
and forth and hopefully leave it alone). Running at 12V, they run 24/7
for years...
FYI,
Corey
Some of you may know that Bob Pease and Bob Widlar are (Widlar is dead) two of the most respected analog IC designers in the world. Unfortunately, I haven't seen any empirical data from either of them to corroborate these claims."This reverse current - even if it's as low as nA or very brief in duration - tends to degrade the low current beta at least on a temporary basis. So in cases where accuracy is important, find a way to avoid reverse-biasing the inputs. Bob Widlar reminded me that the high current beta of a transistor is generally not degraded by this zenering, so if you are hammering the Veb of a transistor in a switch-mode regulator, that will not necessarily do it any harm, nor degrade its high-current beta."
Roff said:Here's a quote from Bob Pease:Some of you may know that Bob Pease and Bob Widlar are (Widlar is dead) two of the most respected analog IC designers in the world. Unfortunately, I haven't seen any empirical data from either of them to corroborate these claims.
audioguru said:The continuing avalanche breakdown of the emitter-base junction of a transistor might cause its hFE to reduce to 50 from the original 200. But a simple mulivibratpr will keep on oscillating until the hFE drops below maybe 10 (depending on the value of its base resistors).
A high frequency oscillator might destroy its transistors sooner than a very low frequency oscillator.