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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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18th Oct 2015, 2:31 pm | #1 |
Pentode
Join Date: Jul 2014
Location: Bangalore, India
Posts: 132
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Permeability-tuned Crystal Radio
Here's an update.
It's uses an empty lip salve stick as a tuning mechanism. Read more..... http://nandustips.blogspot.in/2015/0...tal-radio.html Regards, Nandu. |
18th Oct 2015, 7:31 pm | #2 |
Guest
Posts: n/a
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Re: Permeability-tuned Crystal Radio
I had an old crystal radio that used a variometer (variable inductor), much the same idea as yours but before the days of ferrite. Good to keep the old ideas going with a modern twist (pun intended!).
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19th Oct 2015, 7:07 am | #3 |
Pentode
Join Date: Jul 2014
Location: Bangalore, India
Posts: 132
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Re: Permeability-tuned Crystal Radio
Hi Merlin,
Yes, it's fun to re-create and understand established concepts! Many thanks. Regards, Nandu. |
19th Nov 2015, 8:56 am | #4 |
Nonode
Join Date: Jul 2005
Location: Hull, East Yorkshire, UK.
Posts: 2,087
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Re: Permeability-tuned Crystal Radio
Can you do anything with a re-cycled and re-wound IF transformer?
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19th Nov 2015, 12:50 pm | #5 |
Dekatron
Join Date: Jul 2008
Location: Charmouth, Dorset, UK.
Posts: 3,601
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Re: Permeability-tuned Crystal Radio
I also have used variometers. You can wind a coil on almost any insulating material, a toilet roll centre used to be favourite in the '40/'50s
Peter |
19th Nov 2015, 2:21 pm | #6 |
Pentode
Join Date: Jul 2014
Location: Bangalore, India
Posts: 132
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Re: Permeability-tuned Crystal Radio
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19th Nov 2015, 3:01 pm | #7 |
Nonode
Join Date: Jun 2013
Location: Surbiton, SW London, UK.
Posts: 2,801
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Re: Permeability-tuned Crystal Radio
Variable inductors with adjustable cores were used as convergence controls in older
colour tv sets, these can be used if they have a value around 500uH. |
19th Nov 2015, 3:15 pm | #8 |
Dekatron
Join Date: Feb 2007
Location: Lynton, N. Devon, UK.
Posts: 7,087
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Re: Permeability-tuned Crystal Radio
Variometers were used, and probably were cheaper than variable capacitors!
However, they are not permeability tuned as there's no moving core - the windings are shifted so that the various sections are more or less coupled to each other. It alters the inductance as a whole, but strictly I suppose it's OT for this thread! |