crystal radio: the first real free energy device

[pomodoro]

The detector [diode) can charge a capacitor and you can then discharge it at will. The most power would be gained from no detector and a resistor as load across the tuning coil/cap. The value of the resistance for max power needs to be determined experimentally.

[Pirate88179]

If we dont use a detector, can the circuit build higher voltages if let to do so? Just wondering. Seems that the transmitters send out quite a bit of high amplitude signals. Maybe some super fine tuning can produce more out.  Say if the tuned circuit is allowed to build, then take some when it reaches a predetermined higher level.

Mags

I was also thinking about something similar for later.  I can hook up my 650 F cap and let it charge for a long time....then use that stored energy.
Maybe I can add a switch and a small amplifier circuit (to run a small speaker) so, when the cap is fully charged, it can run the amp for a while, then switch back to reg. crystal radio power and let the cap charge up again?

Bill

[Magluvin]

I was also thinking about something similar for later.  I can hook up my 650 F cap and let it charge for a long time....then use that stored energy.
Maybe I can add a switch and a small amplifier circuit (to run a small speaker) so, when the cap is fully charged, it can run the amp for a while, then switch back to reg. crystal radio power and let the cap charge up again?

Bill

Hey Bill

Was thinking, instead of taking from the tank every cycle via diode and load, let the tank build in potential before taking from it.  Hadnt made a crystal set in 30 years. So it interests me now, how high can that potential be in the receiver tank if left to do so without taking from it till it reaches some higher level. If we keep taking from it, the signal is damped every cycle.  So we make a set without the diode and see how high it can build, if it does.

I did a circuit on sim a while back where I had 2 loads being driven by a driven resonant tank. Each load was rectified with many diodes in series, one load for each cycle. The diodes provided a voltage drop so the low ohm loads only conducted what was left over after the diode drop. So there was some nice current into the loads without 'killing' of the higher level ring in the tank. I have to look through my codes for that circuit.

Mags

[TinselKoala]

TK:

I decided to use a large peanut butter jar at 3.8" dia.  I ran the numbers using your figure for capacitance for this larger diameter and, the answer I ended up with was 20 turns?  That seems like a very small number of turns.  Does the diameter really make this much difference?  I can re-run the numbers using a smaller gauge wire say like 28, which would require more turns I believe.  I will see what happens.

The cool thing about using a peanut butter jar (plastic) is that you can contain the entire radio circuit in side the jar with the windings on the O.D. and hook-up posts mounted in the plastic lid.  I saw someone else do this and this is the only thing I have of a larger diameter right now.

I am not too worried as I have those ferrite rods (.500 dia. x 6" long) that I can slide inside the jar from the top to lower the freqs. I can receive if I get too high.  I just did not think it would look good with only 20 turns.

I know, performance should trump looks...and I agree but...if I can do both that would be better.  I even have some 32 gauge mag. wire and can run the numbers again with that.

Thanks for your help.  As soon as I can afford a slinky, that will be my adjustable antenna.  Perhaps you should alert the Slinky folks about this new use for their old product?

Bill

By a curious coincidence, I have an AM station broadcasting at 1480 kHz with its antenna just a few km from my house. The variometer-tuned crystal set in the picture below has 24 turns on the outer coil and 30 turns on the inner coil, and has a 95 picoFarad capacitor in parallel with the coil set. It tunes the 1480 kHz station perfectly at about the midpoint of the inductance range of the variometer.
The wire on the coil set is #30 Kynar-insulated silver-plated copper wire-wrap wire. The inner coil is 1 5/8 inch diameter and the outer is 3 inches. I use the Slinky antenna with another 100 pF capacitor in series with the antenna as a "matcher".

So yes, I think your capacitor-tuned set might work very well with just 20 turns on the large diameter former. You can always wind more turns and put taps in at 20, 30, 40 turns and see which works best. When you get to 20 turns, just make a "twisty loop" in the wire sticking up and continue winding. See the image of the capacitor tuned set below. Once you're finished winding you can strip the enamel from the "twisty loop" and attach a wire to it for the tap.

[Pirate88179]

TK:

Thanks.  I thought I was using the calculators incorrectly.  It looks like I may miss yet another day of work on Thurs due to another snow/ice storm so, if so...I will have some time to work on this.  It is bad news as I don't get paid but, there is nothing I can do about it.  (They are calling for 1.5-2" of ice in an ice storm turning to snow with a snowfall of 8-10" on top of that. (Starting at noon on Wed.)

We have many stations here on the am band but, I listen to 930 at work and at home as it is mainly talk radio.  You can also get Coast to Coast at midnight.  I just thought it would be cool to be able to get a station I actually listen to.

Are you using a real earth ground?  Or just clipping to the screw on a switch plate or plug?  I can always run a wire out to my carbon rod from my earth battery for a good ground if need be.  Does a really good ground improve performance?  Or, is one ground as good as another?

Thanks again for the help and guidance.

Bill