Simple one transistor circuit

[momo]

Hello there, I am looking to build a simple circuit, clean boost that could take a 6 mv Ipod input and amplify to maybe 3-4v output.
Size is important and would love it if it could be a one transistor circuit.
Any suggestions?
Im basically just trying to have the smallest circuit possible to do this job with no distortion, just a boost.

thanks

[Top Top]

This might work:



Not sure what the voltage of the output would be.

Could also try a 386 chip circuit. Not a transistor but the circuit will be even simpler than a 1 transistor circuit is likely to be and the 386 not exactly expensive...

[CynicalMan]

Simple op-amp amplifier? You could do it in 9 or 10 components. Also, the input impedance doesn't have to be high if you're only using if for iPods.

[momo]

Guys thanks alot for the info. Yep it would only be used with a Nano ipod and would like to make it so it does not distort at all.
Do all clean boosts distort at some point?
Again, smallest circuit possible is important too   

[Top Top]

Any circuit will distort eventually.

[momo]

Right, OK, anyway, I figure to use a trimpot directly on the circuit, so I can fix it at the transistor sweetspot.

[brett]

Hi
the boosters above are all suitable, the BJT form is best for your needs.
Note that 6 mV to 3 V is a massive gain of 500 x.
So - omit the gain control (run it flat out) by using a fixed 10k resistor instead of the pot and bypass it with the 22uF cap.  That will give 300 to 800 x, depending on the transistor.
cheers

[momo]

Brett, will this make the output clean without distortion?
thanks

[petemoore]

  Wire distorts signal...technically.
  2 or 3 volts isn't excessive ?
  Seems like 9v supply should accomodate that, if not a rail to rail opamp wrings out a touch more before signal reaches near headroom = distortion, otherwise upping the suppy voltage [15v or 18v is ~easily had] will of course invrease the headroom.
  Any one of these component types can be used to achieve voltage gain with fine success, opamp of course allow enourmous gain if transistor won't do it.
  35db-clean boost from Mosfet booster ?
  386 will boost meganuff, but is also somewhat inherently dirty.