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(URGENT) Help making LM386 first project.

Discussion in 'General Electronics Discussion' started by AlanW, Apr 17, 2014.

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  1. AlanW

    AlanW

    1
    0
    Apr 17, 2014
    Hi everyone, new user.

    I am making this amp: http://runoffgroove.com/lgmk2-pcb.pdf

    I would like to have 2 potentiometers that control volume and distortion (gain).

    I have these questions:

    1. Are these capacitors polarised.
    2. What does the 220n mean for one of the capacitors.
    3. Which ones are ceramic capacitors or other types.
    4. What does 1M5 mean for one of the resistors.
    5. How do I wire the potentiometer to the circuit.
    6. Can I use any JFET or just the MPF102.

    Please answer quickly I am buying the parts in a few minutes.
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,476
    2,820
    Jan 21, 2010
    1) The capacitors with a + sign near them on the board, or a round and a square pad, or a polarity indication on the actual capacitor ARE polarised. C1, C3, and C4 match this pattern.

    2) 220n means 220nF, or 0.22uF, or 220,000pF, or 0.000022F. It is a measure of the capacitance. In this case 220 x 10^-9 Farads (n == 10^-9)

    3) Ceramic capacitors are often flat discs. C2 and C5 *might* be ceramic. The other capacitors will not be ceramic.

    4) 1M5 means 1.5M which means 1,500,000 ohms. The M is used in place of the decimal point because it's harder to lose an M than a . (out of 1.5M and 1M5, only one can be confused with 15M)

    5) The connections to the potentiometers are not shown. Point us to a circuit diagram and we can try to figure it out.

    6) If you can't find an MPF102, look for another small signal N channel JFET. I'd have to see a circuit diagram, but since this is designed to generate distortion I can't imagine it matters a great deal what you use. In the worst case you might have to change the biasing a little.

    Show your list to whoever you're buying the stuff from (assuming it's in person) and they should be able to make sure you get the right stuff.
     
    AlanW likes this.
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