Saturday, November 5, 2011
Saturday Evening Post
Here is a simple crystal radio I put together from the pages of Gonzo Gizmos.
Bill of materials:
Plastic water bottle (dollar store special)
26AWG magnet wire (Philmore# 12-1226)
Crystal Earphone (Philmore# 748)
A few jumper wires with alligator clips
Ground and antenna wire.
As per the instruction I prepared the bottle with four holes, two on top and bottom for holding wires in place, great tip.
The wrapping of wire for the coil on the bottle took the most time, I used a pencil to make small loops every six turns or so. The loops are for station selection when complete. I used a lighter to burn off insulation from wire ends and loops. Sandpaper also works well. Took my time wrapping the windings to create a neat appearance instead of a birds nest type look.
Pencil used to form loops.
The magnet wire can be any common gauge from 18 to 22, I had a spool of 26 that was 3/4 full. I did not solder my connections but used a wire wrap tool. The detector 1N34A diode picks up the audio frequencies out of the radio wave.
They also recommended trying a telephone headset, I had a crystal earphone handy. As you can see the crystal radio circuit is as simple as it gets. A telephone headset would be interesting to try and see how it would work out, maybe a future build. I found the key is a great ground more than the antenna. My ground of choice was a cold water pipe in the basement.
The final result: the strongest and only station heard was 770 WABC in NY, came through with a soft signal but was audible. The individual loops did not help me much but it might have helped if I removed more insulation from the wires. I think my antenna could have made a better connection with the individual loops. Something to play around with and test.
Another tip is to kill all background noise, TVs, talking, etc., sometimes if not most depending on your conditions signals heard in the earphone are extremely weak. I will draw up the schematic and post it in a few days.
Tweaking the circuit, trying different grounds, etc. I should be able to pull in more stations.
Odds & Ends....
Received the November edition of CQ in the mailbox this afternoon, new reading material is always welcome for the weekends.
Cut the lawn today, only 1-2 more times before the colder temps are here.
Went to my sons football game this morning, soccer tomorrow, (remember "Wide World of Sports") and maybe some radio fun after that.
Have A Nice Weekend!