Instructables

Make a 1-2 uH Output Air Core Inductor for Audio Amplifier

Picture of Make a 1-2 uH Output Air Core Inductor for Audio Amplifier
The output of almost all audio amplifiers contains a circuit of an inductor and resistor in parallel.  The inductor is there to enhance stability in the face of speakers that present a capacitive load.  The resistor is there to dampen potential ringing or oscillation caused by the interaction between the inductor and the speaker capacitance.

The inductor in this circuit must be an air-core inductor as magnetic cores wreak havoc with audio signals.  It is typically in the 1-2 uH range. 
 
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Step 1:

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Here is what you will need. 

1.  Various PVC parts: a small section of 3/4" pipe; a T fitting; a fitting usually used to join/glue two pipes in a straight line, but cut into 2 pieces (I used a band saw) so they can slide onto the 3/4" pipe; and a large pipe fitting that I believe is a compression joint (not sure exactly what it is but they are easily found at Lowe's).  I did not use PVC glue but you may want to on the T-handle.

2.  14 Gauge coated magnetic wire. I chose this gauge to minimize the resistance of the wire - the amplifier I am building is 200W per channel so I need a very heavy gauge.

3.  Some 3/4" electrical tape

4.  Tools: Not shown in picture but you will need wire cutters, box knife, and scissors.  A drill and small drill bit. A band saw or hack saw to cut PVC pipes and fittings.

5.  Optional - a meter for measuring inductance.

Step 2:

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Put the T-fitting onto the 3/4" pipe - it will be your turning handle.  Slide the pipe onto the compression joint (again, if that is what it is called) making sure that the 3/4" pipe is loose enough to turn.