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Old 05-09-2012, 05:05 AM
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jake jake is offline
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Join Date: Nov 2007
Posts: 169
Originally Posted by dR-Green View Post
If you remove all the diodes from the radio setup and the load from the power setup then you are left with only a capacitor across the primary so a very simple arrangement. As far as I can make out the bulb affects the capacitance/tuning so the 2nd cap is possibly in series with the bulb to reduce the extra capacitance. Either way if you just use the single cap and no load you can see on the scope how the reception (or "activity" in the primary) changes by adjusting the primary capacitance and the secondary condenser plates accordingly.

Nice, you just made me notice that the radio setup doide/capacitor/high z arrangement looks like the "AV plug / speaker" I made. Just replace the capacitor with the LED.

Originally Posted by dR-Green View Post
With my spiral for example by setting it up like that and tuning for best signal in the primary with no loads at all except a scope, to hear the radio all I need to do is place the C0 plate from Eric's radio diagram 25+cm away from the secondary terminal. That reduces the voltage in the primary but not too much because it's so far away relatively. This is probably where the flat spiral and TMT start to differ more significantly, but employing variable condenser plates and a separate receiver/C0 plate is a big improvement over using the C0 plate as both the receiver and tuning condenser, before needing to be within 5cm distance of the terminal to bring the frequency down enough and still hear the radio. Now it's already tuned without the C0 plate as can be seen in the primary.

Does the LED still light if you remove the speaker? It could be acting like a microphone although I don't see why it would work only in certain places in that case. It would be interesting if it still lights without the speaker
Yes it will light without the speaker. I have three different plugs I have been playing with. They all light the led.
One is just like the one in the picture. Another is just like that but also has a ~50pf cap across it. The last does not have the speaker or capacitor.

Capacitance is needed on either side of the LED between the diodes and LED. I can hold it or sometimes just attaching an lead will work. If I feed it a signal using an extra 1 turn tuning coil it will light without the capacitance on the LED.

ALSO and a bit off topic but... IF YOU THUMP THE CRYSTAl SPEAKER THE LED BLINKS SUPER BRIGHT... It cought me off guard. And took me about 10 seconds to realize what happened.

I knew the potential for that to happen was there but I never thought it would do that to an LED with a little tiny thump.

now back to work.
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