Posted on 11/02/2010 10:48:58 AM PDT by djf
/johnny
I am not surprised. lol. You can learn anything on FR if you keep asking.
Be wary. Some older homes did not carry 3-conductor wiring, so some people would install NEW three conductor (neutral ground) PLUGS, but the GROUND is not connected to anything.
Best bet is to see if there is a REAL Ground.
Best choice is the steel rod stuck in the ground for your TV ROOFTOP antenna ground, or the ones that PHONE CO's and CABLE CO's put into the ground.
Barring that, ground to your WATER PIPE.
Steely Tom,
Please stop giving out bum dope. The correct answer is “Add a Ground.”
Lol! Ask Obama!
I thought Al Gore invented radio!
Thanks for all the replies. It’s an interesting project because most crystal sets tune by adjusting the contact point with the coil. But building your own variable capacitor is a neat stunt!
Probably a razor blade, more likely. WWI soldiers used to build receivers in the trenches out of them.
That is pretty cool
Do you mean like a "bong", or a pipe that carries water?
A real 'ground'. Don't depend on that ground plug on your house electrical outlets. It many times is not even grounded, or is a really poor ground.
His best bet would be to drive a steel or COPPER rod into the ground and connect to it.
Very good! I should have said that was step #1!
Listen, djf, if you're in a submarine, make sure the "ground" connection is solidly attached to the boat's hull or propeller shaft.
That is one of the many reasons why I visit this place! ‘Tis a fountain of knowledge.
No, more turns on the coil mean more resistance and greater loss. You’d just be tuning it differently. Using thicker wire might help, less resistance, but it’s hard to turn it as tightly.
You might also consider a four diode bridge.
http://en.wikipedia.org/wiki/Diode_bridge
With one diode you only absorb half of the incident energy from the antenna. The problem is you double the loss through the diodes, so maybe the gain isn’t so spectacular.
Your quickest improvement is probably available in the placement and length of the antenna. (Again, thicker wire might help.)
http://en.wikipedia.org/wiki/Monopole_antenna
The incident wave from a commercial AM broadcast is strongly vertically polarized, meaning the electric field varies in the vertical direction. The antenna will work better if it is aligned with field, meaning running up a pole vertically. However, it is important to keep it as straight as possible. (I assume this in an AM set.) Further you might want to cut the length of the antenna to approximately a quarter wavelength, but that is probably not feasable. The closer you come to quarter-wavelength, the better you rig should work.
Also, try to route your antenna wire so that it is not too close to any other wires (including the ones inside the walls or your house) or other conductors, like aluminum siding.
Good luck!
The one that goes to the ground, not the one that leads to a high.
So how are you voting on Prop 8? ;~))
Thanks! Good tips!
If your bong is copper, and is embedded at least 8 feet deep into the earth, you may clip your crystal set to your bong. Otherwise, use a copper cold water pipe and make sure that there's a copper jumper across the water meter if the water meter is located in your basement. You want a solid conductive path to ground.
I'm sitting at an election poll right now, using my phone to enter this post. When I get home tonight, I will sit down at the computer and go into some real detail for you, as well as send you some info by e-mail if you wish. I build these things from scratch as a hobby... My first one covers broadcast band all the way through 6 megahertz shortwave, so I have done nothing but improve on the designs ever since. There are some neat tricks that I can share that will really amaze you when you hear stuff from around the world.
Regards,
Raven6
P.S.: Almost forgot... Ditch the little earphone piece and get yourself a good set of high impedence headphones (2000 ohms or higher) from eBay or such. A good set of Ball headphones (antique, but cheap enough and not as expensive as the old collectible ones) does a great job! I've bought 3 sets on eBay and the most expensive set was about $12.
Oh, in case you're wondering where all that current comes from, well, nature always keeps her books straight. As soon as you tune that capacitor to the station of your choice, all the lights in that station will get dimmer by a few percent. They'll hardly notice it, though. Might even cause the street lights near the station to dim down too, if you're listening at night. That's why I always wear a nice, tight tinfoil hat whenever I use my crystal set.
P.S. This is sarcasm, djf.
20 amps? Really?
You mean if my juice goes out, I can run my fridge off of my crustal radio? I bought that generator fer nuthin?
LMAO!
Thanks for all the tips! I’m listening and learning and trying things. I admit I am very suspicious about the quality of the ground on the home electric setup. Probably a perfectly good ground for 60Hz 120V but might be not-so-good for the ultra small current at the frequencies we’re talking about.
A ARRL hand book will give you many ideas on simple amplifer circuits.
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