 |
PM |  | |
Quote | | |
Reply | | |
Full Topic | |
| Joined: | Dec 12th, 2007 |
| Location: | Dunedin, Florida USA |
| Posts: | 38 |
| Status: |
Offline
|
I've been working on a Raudive diode circuit and having trouble understanding the need for the antenna. Measured at the antenna - diode junction, without the 500uH coil connected, I see a signal level of approximately 2-4 mV. Even using a germanium diode with its 0.3 volt forward voltage reqirement, I don't see any way this low level signal will get through the diode. As far as I can see the diode only acts as a noise source to the recorder's microphone input. It looks like the antenna and coil are completely superfuous.
In order for this Raudive diode circuit to work it appears that the EVP signal level would have to jump up above the 0.3 V level. That ought to make the EVP really loud and clear?
What signal voltage are you seeing on the antenna on your device?
I think the 500uH coil is being used as a high pass filter. That how you see it?
I've begun experimenting with biasing the diode to about 0.5 volts to that the antenna signal flows through the diode within its conduction zone. At least this way the 2-4 mV signal gets through. My next step is to amplify the signal to a level that my digital recorder can reasonably record.
Your thoughts?
Bruce