New Crystal Radio Design - "Modified-Pickard"

A different crystal radio and a comparison to the original "modified Boy Scout" radio I made earlier. Also a new (better) way to do the wiper.

Depending on your design (coil mostly) it can receive in the AM broadcast band, approximately 535 to 1700 kHz.

There is a similar design sold as a kit they call the "Pickard" however they include a capacitor across the antenna / ground leads which I found was no help. They also used a much higher value resistor which lowered the sound volume with my earphone.

Construction techniques are the same at the modified Boy Scout radio and that video can be found here:
   • How To Make A Crystal Radio - No Batteries...  

And some improvements:
   • Crystal Radio Upgrades & Build Details  (U...  

See Warnings below.

Here's my favorite crystal radio build:
Best/Easiest DIY Crystal Radio - No Batteries, No External Power 2023 (4K)
   • Crystal Radio-How To Make The Best/Easiest...  


OPERATION TIPS & TRICKS
A good antenna is important. Longer is usually better (see antenna warning below), a good ground is next most important. For the video I used about 15 meters or 45 feet. 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.

TOOLS
Screw driver
Knife
Sandpaper (small piece, fine)
(Optional) Saw, if you do not have the wood & tube already cut
(Optional) Hand drill for screw holes
(Optional) Soldering iron, solder

MATERIALS
1 x Germanium Crystal Diode (1N34A)(bought: Amazon, Radio Shack 276-1123, Digikey, Jameco, Mouser...)
1 x Resistor (10k ohm, carbon, not wire wound)(bought: ditto)(see note below)
1 x Crystal earphone (can NOT be other type)(bought: Amazon, Jaycar, Jameco?) MUST be like the type in the video. Regular iPod or similar will NOT work.
1 x Base 21 x 17.5 cms x 2 cms thick or more (wood scrap)
1 x PVC pipe 15 cms long or stiff cardboard tube x 2.5 inch diameter
1 x motorcycle / bicycle spoke, 2mm diameter or brass rod or stainless rod
Wiper pylon: Wood block, carriage bolt (2.5"), spring, 3 stainless or brass washers, 2 screws to attach block.
Enameled bell wire (can be from old transformer, solenoid, ...) 0.3 to 1.5mm (note: I used 0.5mm or roughly 19-20 AWG, the number of turns and length of pipe change with wire size.) Bigger wire has lower resistance (better sound), BUT you get fewer turns per centimeter (less tuning).
Screws, stainless or brass (6 for wire hold downs, 2+ for coil mounting),
Fahnestock clips (2) (bought: Amazon & electrical shops). OR brass washers (13) (bought, hardware store)

ANTENNA & GROUND
The antenna is just a long piece of wire (I use scrap wire from old transformers, fluorescent light ballasts and such). The longer the better.
Try different lengths and orientations (vertical, horizontal)
A good ground helps. A wire to a ground rod is good. Metal water pipes also work well.

NOTES:
The modified Boy Scout radio has about 170 turns, this new design has 138 turns.
The resistor is necessary to get the best sound from these "new" crystal earphones. The new ones are piezoelectric and have lots of capacitance. Without the resistor the charge builds up then discharges so you get constant "static" sounds. The resistor bleeds off charge so you get louder, and much clearer sound.
Also called a foxhole radio.

WARNINGS:
Never connect radio to any source of power. Not house current, nor batteries, nothing!
Never use the radio during lightning storms.
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.

OTHER:
An excellent website by an avid and skilled builder:
http://www.lessmiths.com/~kjsmith/cry...

INTERESTING LINKS
Air Core: http://www.circuits.dk/calculator_sin...

(Re-edited for annotations)
#crystalradio
#piezoelectric
#DIY
#boyscoutradio