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Homebrew Equipment A place to show, design and discuss the weird and wonderful electronic creations from the hands of individual members. |
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14th Jan 2019, 5:35 pm | #21 |
Octode
Join Date: Nov 2013
Location: Penrith, Cumbria, UK
Posts: 1,993
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Re: "The Works" Crystal Radio
A quick google suggests the ST4148 is a zener diode but I think it's as everyone says a 1n4148 100V 1A rectifier. The datasheet says 1V Vf. I think the ST prefix probably indicates the manufacturer?
I'm going to have a look in town on wednesday while we are in and I might buy one out of curiosity. If nothing else I think it could be possible to mod it with a variable capacitor and I might see if there are any strongish signals here in the frozen wilds. A. |
14th Jan 2019, 6:19 pm | #22 |
Moderator
Join Date: Jun 2003
Location: Oxford, UK
Posts: 27,970
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Re: "The Works" Crystal Radio
The 1N4148 isn't a rectifier, it's a general purpose silicon switching diode, probably the cheapest diode of any type available.
https://en.wikipedia.org/wiki/1N4148_signal_diode |
14th Jan 2019, 6:34 pm | #23 |
Octode
Join Date: Nov 2013
Location: Penrith, Cumbria, UK
Posts: 1,993
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Re: "The Works" Crystal Radio
My mistake Paul. Got distracted by the Reverse voltage and current data when I did a quick google.
I wonder if its a batch of discontinued stock as ST microelectronics don't list it. Or more likely something swept off a production line in a Chinese knock off plant. A. |
15th Jan 2019, 4:19 pm | #24 | |
Heptode
Join Date: Dec 2014
Location: Lincoln, Lincolnshire, UK.
Posts: 583
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Re: "The Works" Crystal Radio
Quote:
I plotted a curve for my ST4148. It spot reads about 0.6mA forward at 0.6V (starts conducting around 0.4V). |
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15th Jan 2019, 7:18 pm | #25 |
Nonode
Join Date: Jan 2016
Location: Stafford, Staffs. UK.
Posts: 2,532
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Re: "The Works" Crystal Radio
I just had a look out of curiosity. I laughed out loud!
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16th Jan 2019, 1:36 pm | #26 |
Dekatron
Join Date: Aug 2013
Location: Wigan, Greater Manchester, UK.
Posts: 9,433
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Re: "The Works" Crystal Radio
While on the subject of crystal sets, this may be of interest.
https://www.americanradiohistory.com...l-Sets-v12.pdf
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Frank |
16th Jan 2019, 1:55 pm | #27 |
Octode
Join Date: Jun 2004
Location: Reading/Fakenham, UK.
Posts: 1,326
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Re: "The Works" Crystal Radio
Circuit 7 from Frank's "The Boy's Book of Crystal Sets" worked very well. Four MW stations and R2 on LW - all in 1973-ish. Maybe I was lucky that at the time, in Bury Lancs, all the strong stations were nicely spread out across the band.
That is one of the circuits that spurred me on the more investigation; adding transistors, and - eventually - a career in radio...! |