audioguru Posted May 16, 2006 Report Share Posted May 16, 2006 The projects don't say how much range they have.Make them and let us know. Quote Link to comment Share on other sites More sharing options...
crivoli Posted May 16, 2006 Author Report Share Posted May 16, 2006 I agree it does not specify the range, but this 'should' work in my scenario correct?I don't want to try them if they are not useful to me. If you think they will work for my project I will give them a shot.I would builf the receiver first to see if I could get AM stations on it. Why doesn;t the receiver have an antenna? Is this normal?Thanks Quote Link to comment Share on other sites More sharing options...
audioguru Posted May 16, 2006 Report Share Posted May 16, 2006 Why doesn;t the receiver have an antenna? Is this normal?AM radios don't have an external antenna. They use a ferrite rod which has the coil wound arround it. The transmitter might need a very long wire for an antenna for it to have any range. Quote Link to comment Share on other sites More sharing options...
crivoli Posted May 16, 2006 Author Report Share Posted May 16, 2006 audioguru:I appreciate your patience with me.Would this work for the am receiver as the 220uH component?http://cgi.ebay.com/Ferrite-Loopstick-Antenna-Coil-Crystal-Radio-Radios_W0QQitemZ6619389741QQcategoryZ7275QQssPageNameZWD1VQQrdZ1QQcmdZViewItemalso I can not seem to find any good variable capacitors..... any suggestions?thanks man Quote Link to comment Share on other sites More sharing options...
audioguru Posted May 17, 2006 Report Share Posted May 17, 2006 The article for making the radio says to get a loopstick antenna and tuning capacitor from an old AM radio.The E-Bay loopstick antenna coil is fine. Also get the guy's tuning capacitor or the kit AM crystal radio that has both. Quote Link to comment Share on other sites More sharing options...
crivoli Posted May 17, 2006 Author Report Share Posted May 17, 2006 The AM receiver schematic specifies a 500pf variable capacitor.The one on E-bay is 60/160pf. Do you think that will work, or will I need to change values of other coponents on the schematic? Thanks Quote Link to comment Share on other sites More sharing options...
audioguru Posted May 17, 2006 Report Share Posted May 17, 2006 Crivoli,Don't you realise that the variable capacitor has to match the value of the ferrite loop coil antenna? Quote Link to comment Share on other sites More sharing options...
crivoli Posted May 17, 2006 Author Report Share Posted May 17, 2006 audioguru,No I didn't realize that. How then on that schematic is the antenna a 220uH and the resistor is a 500pf? Do you have to tune the capacitor until it reaches the matching value? Quote Link to comment Share on other sites More sharing options...
audioguru Posted May 17, 2006 Report Share Posted May 17, 2006 The value of the E-Bay ferrite loop antenna coil isn't listed but it could be calculated since the value of its tuning capacitor is known and also the tuning frequency range.The 220uH coil has a low value so it needs a high value tuning capacitor to tune the AM tradio band. Quote Link to comment Share on other sites More sharing options...
crivoli Posted May 17, 2006 Author Report Share Posted May 17, 2006 So, I could be safe in replacing those components of the schematic with those I found on e-Bay. Does that sound right?Also, on the transmitter schematic it is not clear of what L1 is:http://www.electronics-lab.com/projects/rf/011/index.htmlIs it another ferrite coil, or magnet copper wire? I assume it is another ferrite coil since this is AM and it's tuning cap is the same value as the other.thanks again Quote Link to comment Share on other sites More sharing options...
audioguru Posted May 17, 2006 Report Share Posted May 17, 2006 The transmitter and receiver both use the same ferrite rod loop antenna coil and tuning capacitor. Quote Link to comment Share on other sites More sharing options...
crivoli Posted May 17, 2006 Author Report Share Posted May 17, 2006 So am I able to replace the coil and tunning capacitor in the schematic with any coil and tunning capacitor I find that are compatable with each other?Thanks Quote Link to comment Share on other sites More sharing options...
audioguru Posted May 17, 2006 Report Share Posted May 17, 2006 So am I able to replace the coil and tunning capacitor in the schematic with any coil and tunning capacitor I find that are compatable with each other?Correct. Then the radio can tune in the entire AM broadcast band. Quote Link to comment Share on other sites More sharing options...
crivoli Posted May 18, 2006 Author Report Share Posted May 18, 2006 The designer of the AM ciruit said he built this on a breadboard.Any idea how to hook up a variable cap on a breadborad since the connectors don't fit? Quote Link to comment Share on other sites More sharing options...
audioguru Posted May 18, 2006 Report Share Posted May 18, 2006 Solder wires to the variable capacitor and plug the wires into the holes in the breadboard. Quote Link to comment Share on other sites More sharing options...
crivoli Posted May 18, 2006 Author Report Share Posted May 18, 2006 I was going to use alligator clips :) Just wanted to make sure this wouldn't throw anything off.Thanks again Quote Link to comment Share on other sites More sharing options...
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