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Step 8Testing the AM Radio Circuit
This step is a circuit test of the Tesla Spirit Radio, to see if it works as an ordinary AM radio. Once the wiring and solder connections are double checked, we can test the AM radio part of the device.
Plug in the Audio Patch Cord into the 1/8 inch jack of the radio, and then into the computer "Sound In" port. Launch Audio Hijack (or equivalent PC software). Set up with a basic 10-Band EQ and two or three AU Pitch controls. AU Bandpass and Reverb won't be used for this test...use their "Bypass" buttons. Gain may need to be turned up high. Au Pitch controls at the neutral 0 pitch setting. (See screenshot below.)
Turn the variable capacitor knob and the sounds of a local AM station should come through; if not, a long antenna may be required in your area. Try touching the jar ring or antenna to see if that makes a difference.
If you have no sound at all, then something is likely wrong. Check for a dry solder connection. Also, if too much soldering heat was used close to or on the diode connection, the diode may be burned out. Substitute to check, or use the diode checker function of your multi-meter to test it if necessary.
Plug in the Audio Patch Cord into the 1/8 inch jack of the radio, and then into the computer "Sound In" port. Launch Audio Hijack (or equivalent PC software). Set up with a basic 10-Band EQ and two or three AU Pitch controls. AU Bandpass and Reverb won't be used for this test...use their "Bypass" buttons. Gain may need to be turned up high. Au Pitch controls at the neutral 0 pitch setting. (See screenshot below.)
Turn the variable capacitor knob and the sounds of a local AM station should come through; if not, a long antenna may be required in your area. Try touching the jar ring or antenna to see if that makes a difference.
If you have no sound at all, then something is likely wrong. Check for a dry solder connection. Also, if too much soldering heat was used close to or on the diode connection, the diode may be burned out. Substitute to check, or use the diode checker function of your multi-meter to test it if necessary.
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This seems to be a solution for PC users, but it is expensive to purchase.
You will not be able to hear the radio through the computer without increasing the gain substantially. One way the gain can be increased is by adding additional antenna length; generally the longer the better. Touching the antenna will tend to do the same as a test.
A good ground will help too for gain, but I needed no extra antenna, or ground, when doing most of my experiments.
The radio signal gain needs be radically increased by software. In the Audio Hijack software (for Mac), I use a Gain module and three more AuPitch modules in series to increase the gain enough to hear properly.
The software "ProTools" might work for you. I'm sure there are others that work in real time to increase input gain and shape the sound. I need to explore the real time audio software options for the PC, but first I need to get a PC! That will happen soon...
Alternatively, you could run the output of the radio through a pre-amp, and then hook the pre-amp into the computer sound-in.
You should at least get a hum or some sort of noise. The hum should be very loud when touching the centre tip of the patch cord with your finger, then should mostly go away when plugging in the radio.
Make sure the connections are good by a continuity check between the patch cord ground(outer) and the centre terminal of the variable capacitor. Then check continuity between the tip of the patch cord and the diode.
Good luck and let me know.