Speakers rule! And this one is surprisingly loud. My work area is about 15' X 15' and I can hear this little hummer easily from any spot in it. No need for a volume control however!
I cannot for the life of me remember where I got the plan for the 1T4 amp stage but all it amounts to is a mini audio transformer from Mouser with two leads to the crystal set's output and the other two to the tube. This crystal circuit comes from Dave's #61 double tuned crystal set. It should be apparent by now that I am pretty much a permanent leach on Dave's expertise. There is none better to draw from!
A slide switch selects diode detection or the pyrite detector stand mounted on top and up front (and center!). This stand is what I call my 'Open Style Detector Stand' and is very smooth and accurate with that split-ball housing cup control. The basket weave coil is wound on threaded styrene pegs that are screwed into a nylon hub. I used .03" magnet wire for a 240uH finished unit and mounted it 2" above the top plate.
Since the 1T4 tube is so small I opted to 'give it a raise' with some clear acrylic tubing. I mounted the socket inside a plate of black acrylic...same stuff the top plate is made of. All that booming power comes from a 3"x2"-4 ohm speaker which cuts out when earphones are plugged in. What will they think of next?
This set features a five sided glassed in cabinet of padauk. I do have other species of wood but I sure like this red stuff! Any way, the knobs were made from a section of padauk that has some white 'heart wood' in it and both have a mother-of-pearl button inlaid in the center.
This set is sold. Page remains for reference only.