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fawlty
modified 12 years ago

The Fawlty Amp. Single transistor amp.

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00:41:50
How can I scale the output for a full 1 to 6 volts for my +/- 250mv ?? It's a pitty there's no audio in / out (scaled) on this...
published 12 years ago
mjakubec
12 years ago
Your amplifier doesn't have operating pointadjusted properly, i.e. signal being amplified will be severely distorted. Put a supply voltage divider to the base of the transistor so there will be approx. 0,76 V. Additionally, try to lower resistance of the resistor placed in the emitor of the transistor, you will get a higher voltage gain.
mjakubec
12 years ago
And, of course, put a capacitor between the signal source and an input of the amplifier to isolate the input from DC voltage.
rbrtkurtz
12 years ago
Not quite there yet. Your values are crazy. Try googling common resistor values, or there is a handy little app called Driod Circuit that has lots of calculators, example circuits, and lists of common values. I'm pretty sure it's free, too. Here are a few of the issues I see right off the bat for a single transistor amp: 1, depending on the source, 1V can be a lot. Guitars tend to put out 100-250mV, though with certain pickup combinations they can reach nearly a full volt. My phone, wide open, puts out about 400mV through the headphone jack. 2, you'll want a voltage divider at the base. 3, that filter cap you have on the input it's wacky. 2.2uF is common there. I'll let you research why. 4, 100 milliohm? Really? 5, is that 5K resistor supposed to be the speaker? Speakers are usually 4, 8, 12, and 16 ohm. There. Are others, but that's your garden variety. You'll want 4 or 8 ohm with this amp. I'll post a generic, single transistor amp for you to look at.
rbrtkurtz
12 years ago
As a matter of fact, I won't. You can Google common emitter amps all day long. Pete from Sparkfun has a great video on the topic, as well. I highly suggest watching. https://www.youtube.com/watch?v=IkabRft5Sdk&feature=youtube_gdata_player
thebugger
12 years ago
Your topology is mostly wrong. It needs too much corrections for me to explain to you
Secuture
12 years ago
Oh yes here a whole seminary is required about amplifiers it wil kill my fingers writing 3 days cuz i'm mad crazy guy who suffers from "write'a'lot" psychosis. But idea about complete single transistor audio amp hose join preamp with ton controll drive and output stage is genial!!! I get into wok

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