My New Favorite! Crystal Radio with Antenna Tuner

The wiper style crystal radio is easy and cheap to make. It has a few drawbacks including: cross-talk, tuner roughness and selectivity. This new design uses all the same easy construction techniques and low cost of materials. It really works well. It's now my new favorite!

Depending on your design (coil mostly) it can receive in the AM broadcast band, approximately 535 to 1700 kHz. In actual use I have received from 1295 to 540kHz. On the 1295 kHz I had to short out part of the left side coil using only about 2/3rd of the turns. So fewer windings on the left side would be better.

See Warnings below.

OPERATION TIPS & TRICKS
- A good antenna is important. Longer is usually better (see antenna warning below), a good ground is next most important. More below
- With some stations, you can put a finger or 2 or 3 inside the tuner coil to improve reception. Move them around for best reception.
- A finger near the coil can also improve reception. Touching the coil directly usually lowers sound volume, BUT a piece of paper or thin plastic between finger and coil often improves sound / tuning. Move finger around.
- Touching different parts of the radio or getting near them can affect performance.


MATERIALS
- 3" PVC pipe (3.5" OD), 18 cms long. NOT painted.
- Left side coil: 55 turns, 0.55mm enameled wire
- Right side coil: 110 turns, 0.55mm enameled wire
- Note: 5 turns blank space between left and right coils
- 2 bike spokes/stainless rod, about 2mm, about 18 cms
- 2 wood/plastic knobs for wipers
- 2 Fahnestock clips and screws
- 6 brass washers
- 3 stainless screws (for wire connections)
- 1 crystal earphone
- 1 diode, 1n34a (MUST be this)
- 1 resistor 30k-40k ohms (experiment for best sound), carbon, not wire wound
- 4-6 washers (depending on design)
- 2 screws (to secure wipers)
- 2 felt disks (or springs)
- 2 wood "towers", 1x2 inch (1cm shorter than the MOUNTED coil)
- 4 screws (under towers)
- 1 Wood base 20cms wide x 17 cms deep
- 2 pillow blocks to hold coil
- 4 screws to hold pillow blocks to base
- 2 screws to hold coil to pillow blocks
(See other videos on construction details of wipers, knobs)


WARNING: Radio antennas represent a fire, shock, electrocution, etc. hazard.
- Always disconnect antennas and ground outside when not in use.
- Never connect radio to any source of power. Not house current, nor batteries, nothing!
- Never use the radio during lightning storms or if lightning is expected.
- Never run an antenna over or near power lines.
- Disconnect antenna when not in use.
- Never ground to electrical items, plugs or similar.
- If you don't know, don't do it.

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