|View single post by ArizonaEvp|
|Posted: Apr 10th, 2013 09:27 AM||
|As we have seen, the Raudive diode is nothing more than a crystal radio with a very short antenna.
If you do an online search for crystal radio kit or crystal radio schematics, you will find many kits, plans and parts to choose from in all price ranges.
If you want to experiment in the shortwave band, a search for shortwave crystal radio will point you in the right direction.
AND……you can get FM from a crystal set. Search for FM crystal set and look at the website by a guy named Solomon. He has a couple of very attractive designs.
If you do experiment with any of the crystal set designs, keep in mind that you cannot use regular headphones or earbuds to listen to the audio output. You will need high-impedance headphones or piezo earpieces.
Low impedance inputs like headphones and earbuds (8 ~ 16 ohms) require more current which causes more power loss in the diode; which in turn mean less signal that gets turned into sound.
Using a digital recorder or computer to record Raudive diode circuits or crystal sets should be fine because of the higher impedance of these inputs.
For example; the microphone jack for my Olympus vn3200pc recorder has input impedance of 2K ohms. My Olympus DS-40 has a microphone impedance of 680 ohms. The microphone input on one of my soundcards is >4K ohms.
To be sure…please consult your equipment specifications.