Electronics > Beginners

Crystal Radio Breadboard - Zero Sound

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GeoffreyF:
The antenna should be only one conductor and extended out, not touching the ground.   It should be mainly vertical, not horizontal. So attach the other end to a tree or whatever with a bit of string, not the wire itself.

The diode should be germanium, point contact type. If it was sold to you for this purpose then I assume it's fine. It's polarity does not matter in this.

I don't know what that resistor is for.  I would remove it.

If you are not close enough to a strong AM station, that could be the fundamental problem.  Tune the capacitor SLOWLY to see if you get anything.

t1d:

--- Quote from: GeoffreyF on December 20, 2018, 02:50:32 am ---The antenna should be only one conductor and extended out, not touching the ground.   It should be mainly vertical, not horizontal. So attach the other end to a tree or whatever with a bit of string, not the wire itself.

The diode should be germanium, point contact type. If it was sold to you for this purpose then I assume it's fine. It's polarity does not matter in this.

I don't know what that resistor is for.  I would remove it.

If you are not close enough to a strong AM station, that could be the fundamental problem.  Tune the capacitor SLOWLY to see if you get anything.

--- End quote ---
Thanks, Geoffrey... I will go vertical, outside, when the weather clears...

t1d:
Sometimes... just sometimes... it is very good to not be married... For grins, I hung the antenna, in the house... Started in the rear bedroom, atop a bar stool. Down the hall to a coat hanger hung on the laundry door. To a bar stool in the den. To my lab desk in one corner of the kitchen. LOL... Maybe 65 feet?

I obtained a good amplitude of background hiss. Its frequency varied with changes in the v cap. However, I did not locate the 710AM station with either the original 120uH inductor, or a 330uH inductor (that tested as .29mH.) I hope to have complete success, once I learn how to calculate the needed inductor value...

The cat was only slightly curious as to what in tar nation was going on...

DJohn:

--- Quote from: t1d on December 19, 2018, 04:50:49 pm ---I would think that I would hear some sort of background noise, regardless.

--- End quote ---

It's been decades since I last played with a crystal radio, so I might be mistaken.  But I wouldn't expect to hear any noise if it's not tuned in to a station.  To get sound from the earpiece, something needs to provide it with energy.  There's not a lot of energy in background noise.  You can normally only hear it when it's amplified.

PA0PBZ:

--- Quote from: GeoffreyF on December 20, 2018, 02:50:32 am ---I don't know what that resistor is for.  I would remove it.

--- End quote ---

It's for discharging the capacitor so it can follow the modulation, otherwise the cap would charge and that's it. (depending on the earphone type used of course)

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