Crystal Radio Tuning Cap
Bookmark this page:
 Yahoo!
 Google
 Windows Live
 del.icio.us
 digg
 Netscape
|
|
|||||||||||||||||||
|
Posted by Dave.H on April 2, 2008, 9:40 am
Please log in for more thread options build it, only thing is, it needs a 250 pF mica trimmer capacitor, and all I can find is a 250 pF APC trimmer, not sure if that would work or not. Trimmer cap is Cat # C-VT250 @ www.tubesandmore.com Schematic: http://www.crystalradio.net/crystalplans/xximages/vestpocket1.jpg | |||||||||||||||||||
|
Posted by John Popelish on April 2, 2008, 11:30 am
Please log in for more thread options This is very similar to the type of capacitor shown on the plans. It should work about as well as the one shown. -- Regards, John Popelish | |||||||||||||||||||
|
Posted by Bob Eld on April 2, 2008, 7:13 pm
Please log in for more thread options
> I found a schematic of a very small crystal radio, and would like to
http://www.crystalradio.net/crystalplans/xximages/vestpocket1.jpg > build it, only thing is, it needs a 250 pF mica trimmer capacitor, and > all I can find is a 250 pF APC trimmer, not sure if that would work or > not. > > Trimmer cap is Cat # C-VT250 @ www.tubesandmore.com > Schematic: Don't expect much performance out of a simple receiver like this. It has very poor selectivity and depending on where you live will probably pull in two, three or more station on top of each other and no adjustment will be able to separate them. Crystal sets like this come form the early days of radio when there were few stations, usually only one in a given area and cross interference was not a problem. Crystal sets can be fun to build for the beginner, but because their performance is so poor, one should not spend much money on them. They are usually made from junk, scrounged parts, oatmeal boxes or toilet paper rolls for coils and so on. Don't pay much for anything, you'll be disappointed. More elaborate sets have more selective filtering and can separate stations a little better, but no simple "tuned RF system" which is what a crystal set is can separate stations on the modern AM band effectively unless you reside out in the middle of nowhere with only one station near by. Look up superhetrodyne. | |||||||||||||||||||
|
Posted by Dave.H on April 3, 2008, 6:41 am
Please log in for more thread options >
found a schematic of a very small crystal radio, and would like to
> > build it, only thing is, it needs a 250 pF mica trimmer capacitor, and
> > all I can find is a 250 pF APC trimmer, not sure if that would work or > > not. >
> > Trimmer cap is Cat # C-VT250 @www.tubesandmore.com
> > Schematic: >
> http://www.crystalradio.net/crystalplans/xximages/vestpocket1.jpg > > Don't expect much performance out of a simple receiver like this. It has > very poor selectivity and depending on where you live will probably pull in > two, three or more station on top of each other and no adjustment will be > able to separate them. Crystal sets like this come form the early days of > radio when there were few stations, usually only one in a given area and > cross interference was not a problem. > > Crystal sets can be fun to build for the beginner, but because their > performance is so poor, one should not spend much money on them. They are > usually made from junk, scrounged parts, oatmeal boxes or toilet paper rolls > for coils and so on. Don't pay much for anything, you'll be disappointed. > > More elaborate sets have more selective filtering and can separate stations > a little better, but no simple "tuned RF system" which is what a crystal set > is can separate stations on the modern AM band effectively unless you reside > out in the middle of nowhere with only one station near by. Look up > superhetrodyne. Found a much better one, with more selectivity, which is what I want. Only thing is, part of it is grounded to the front aluminum panel on the authors radio, I don't want an aluminum panel on mine, do I just connect that grounded section to regular ground? | |||||||||||||||||||
|
Posted by Bob Eld on April 3, 2008, 10:48 am
Please log in for more thread options
> >
found a schematic of a very small crystal radio, and would like to
> > > > > build it, only thing is, it needs a 250 pF mica trimmer capacitor, and
> > > all I can find is a 250 pF APC trimmer, not sure if that would work or > > > not. > >
> > > Trimmer cap is Cat # C-VT250 @www.tubesandmore.com
> > > Schematic: > >
in
> > http://www.crystalradio.net/crystalplans/xximages/vestpocket1.jpg > > > > Don't expect much performance out of a simple receiver like this. It has > > very poor selectivity and depending on where you live will probably pull > > two, three or more station on top of each other and no adjustment will
be
> > able to separate them. Crystal sets like this come form the early days
of
> > radio when there were few stations, usually only one in a given area and
are
> > cross interference was not a problem. > > > > Crystal sets can be fun to build for the beginner, but because their > > performance is so poor, one should not spend much money on them. They > > usually made from junk, scrounged parts, oatmeal boxes or toilet paper
rolls
> > for coils and so on. Don't pay much for anything, you'll be
disappointed.
> >
stations
> > More elaborate sets have more selective filtering and can separate > > a little better, but no simple "tuned RF system" which is what a crystal
set
> > is can separate stations on the modern AM band effectively unless you
reside
> > out in the middle of nowhere with only one station near by. Look up
> > superhetrodyne. >
> Found a much better one, with more selectivity, which is what I want. > Only thing is, part of it is grounded to the front aluminum panel on > the authors radio, I don't want an aluminum panel on mine, do I just > connect that grounded section to regular ground? Yes, If this is a crystal set with no amplification, a good earth gound is important to get sufficient signal. The aluminum panel ground does nothing so don't worry about not having it. You can drive a metal stake several feet into the dirt to get a ground. Modern house wiring normally has a groung rod driven into the soil. It is usually located near the main power panel and can be accessed at an any elecrical outlet on the center terminal. However this ground may be noisy and may introduce hum into your reception. Try it and see. Also, a long wire antenna will be helpful in getting a good signal. | |||||||||||||||||||
| Similar Threads | Posted |
| Crystal Radio Tuning Cap | April 2, 2008, 9:40 am |
| Crystal Radio Tuning Capacitor | December 12, 2007, 4:43 am |
| Radio Tuning | May 25, 2005, 9:21 pm |
| MK 484 Radio - Tuning Capacitor Value? | May 24, 2008, 5:15 am |
| Tuning into an square wave radio transmitter | May 26, 2005, 9:01 pm |
| Crystal Radio Pre-Amp | March 23, 2006, 8:49 pm |
| FM Crystal Radio | December 22, 2007, 5:56 am |
| Crystal Radio Amplifier | May 28, 2008, 6:50 am |
| Re: Kids' "crystal radio", making an amplifier thereof | October 7, 2006, 4:51 am |
| Tuning and its classificaton in robotics | February 27, 2007, 9:55 pm |
| "Induction Balance" coil tuning | January 17, 2005, 11:49 am |
| How to make, where to buy or retune, fine-tune 5-10-15-20 kHz band tuning forks (quartz or ceramic) ? | November 17, 2006, 7:24 pm |
| Satellite radio - radio validation | April 20, 2008, 10:56 am |
| 4-pin Crystal | September 20, 2006, 4:15 am |
| Crystal problem.. | February 6, 2005, 9:56 am |
> build it, only thing is, it needs a 250 pF mica trimmer capacitor, and
> all I can find is a 250 pF APC trimmer, not sure if that would work or
> not.
>
> Trimmer cap is Cat # C-VT250 @ www.tubesandmore.com
> Schematic: http://www.crystalradio.net/crystalplans/xximages/vestpocket1.jpg