Man, you should so make a part 3 where you'd drill down into LOG output as opposed to linear. It was pretty awesome to incorporate into a sound level meter. That's where your solution will completely blow away any standard solutions based on discrete parts and wave-followers (uness they stick in a log amplifier).
hi, can you tell me for building a AM transistor radion, if i want to use 2 transistors as darlington...then use amplifier for further amplification... ,,what should be the value of bias resistor(collector. base)in darlington.....i usually use bias resistor 100k for single transistor ...similarly if i use 3 transistors as darlington..what should be the bias resistor..similarly if i use 4..5..6...
So why do you need Re at all? Or rather, why make the parallel path -- why not just stick the capacitor in front of Re, since you're not really interested in amplifying DC at all?
the dc path is necessary to set up the bias conditions. there's always two ways you need to look at an amp circuit. dc conditions for the biasing, and ac conditions for the amplification. if it were just the one path as you stated, then your Ic and Ie would be zero, meaning ib would be zero, meaning Vbe would be zero putting the transistor in the cutoff mode instead of the forward active mode which is necessary for gain. hmm... maybe i should start selling kits too...
I'd say a transistor is a more fundamental unit to teach with than an op-amp... so thus better for the circuit. Also far simpler and marginally cheaper.
Man, you should so make a part 3 where you'd drill down into LOG output as opposed to linear. It was pretty awesome to incorporate into a sound level meter. That's where your solution will completely blow away any standard solutions based on discrete parts and wave-followers (uness they stick in a log amplifier).
kolyasd 11 months ago
Thank you 2 MIT gurus. Really well explained.
1sanjaygir1 1 year ago
hi, can you tell me for building a AM transistor radion, if i want to use 2 transistors as darlington...then use amplifier for further amplification... ,,what should be the value of bias resistor(collector. base)in darlington.....i usually use bias resistor 100k for single transistor ...similarly if i use 3 transistors as darlington..what should be the bias resistor..similarly if i use 4..5..6...
tiputipu0052 1 year ago
So awesome! Really awesome finally i understand the concept of amplification :D
xXdenhartXx 2 years ago
excelent video!!
darthsexiest2727 2 years ago
Really great video guys. I may need to watch it a few more times to get it all down.
davenelsondotcom 2 years ago
So why do you need Re at all? Or rather, why make the parallel path -- why not just stick the capacitor in front of Re, since you're not really interested in amplifying DC at all?
erikmartin2 2 years ago
the dc path is necessary to set up the bias conditions. there's always two ways you need to look at an amp circuit. dc conditions for the biasing, and ac conditions for the amplification. if it were just the one path as you stated, then your Ic and Ie would be zero, meaning ib would be zero, meaning Vbe would be zero putting the transistor in the cutoff mode instead of the forward active mode which is necessary for gain. hmm... maybe i should start selling kits too...
rekluse23 2 years ago 2
Re is needed to bias the bipolar transistor such that it is in dc operation mode.
placidwaves 2 years ago
that was entertaining and very informative ^_^
so is a transistor in this situation better to use than an op amp for an amplifier?
explosivose 2 years ago
I'd say a transistor is a more fundamental unit to teach with than an op-amp... so thus better for the circuit. Also far simpler and marginally cheaper.
Tibbon 2 years ago
I think the op amp circuit would be far simpler to analyze/design. But I guess it would be overkill when a single transistor does the job.
erikmartin2 2 years ago
Nice. How did you model the piezo element ? It's not really a voltage source.
twilight1138 2 years ago
Now I´ve learned something!
I´ll use that! (the concept)
thx!
crove88 2 years ago
great video! i had never understood what role the capacitor plays in the emitter before this. more videos like this!
lartti83 2 years ago
loved! excelent explanation as usual :)
pekepowah 2 years ago 2