18
Item nr.
An easy-to-build crystal set to a classical design of the nineteen forties.
Production | The Netherlands, 1995. |
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Bands | MW. |
Cabinet | Glass jar. Size 14 cm. Weight 0,4 kg. |
Power | none. |
Documents | Building instructions (Dutch): Part1, Part 2. |
Obtained | 4/1995 from Homebrew. |
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Condition | 8. |
Disposed | Scrapped 4/2020. |
Sound sample | PLAY SOUND ABBA sings Chiquitita. |
To build this crystal receiver yourself you need some parts easily saved from a scrap radio: a tuning condensator, a diode, a condensator (1-10 nF), connectors. The coil is made by winding isolated wire on a toilet roll or similar object. The handwork is easy, but to determine the number of winds some formulas must be used: I found 105 winds (length 8.6 cm) to be appropriate (with antenna tap halfway). This gives you the desired inductance to tune the Medium Wave band (550-1500 kHz roughly). Enclosing it in a glass jar is easy (though I did not find any way to fix the coil, it just dangles) and cheap, and you can always see what is inside.
The headset: I could hear stations using a cheap modern device, a walkman earphone set. The performance can be improved slightly by rewiring it to have the two parts in series. However, this still does not compare to these old-fashioned headsets with high impedance. I get the best results with a 5000 Ohm headset I once bought in Prague. Surprisingly, the output is strong enough to drive a speaker as well. With a 600 Ohm speaker connected, the set delivers about 5uW (5 microWatt) and the sounds come out clearly understandable. It will not make your neighbors complain about the noise, but in a peaceful place it can be heard over several meters.