Step 3: Build the Main Network
Transparent's main "network" is simply an inductor measuring 2.5 micro Henries that is soldered into the path of the positive leg of the cable.
To make the inductor, take a two inch long piece of your oak dowel and wind your 14 gauge solid copper wire tightly around the dowel. In order to get precisely 2.5 micro Henries, you will need something more complex than a multimeter. I went to my buddy's shop and used his LCR meter to measure mine.
Side note: My opinion is that you don't have to make it too precise because a 2.5 micro Henry inductor really doesn't add very much inductance anyway. When I measured the cable without the inductor soldered in, it measured 3 micro Henries by itself. So, without the inductor, if I wanted to add 2.5 micro Henries of inductance, I just needed to lengthen the cable by about 8 feet. Anyway, back to the instructions.
I found that if I wound tightly, I consistently got 2.35 to 2.55 micro Henries with 18 turns around the dowel. I think that's a good rule of thumb to go by if you don't have a complex instrument to measure the inductor.
Once you're satisfied with your inductor, use masking tape to hold it in place around the dowel. Tin the ends so they'll be easy to solder later.