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Loadstone 04-22-2012 06:58 AM

@ Jake....i have used 1N34's but in my clip they are a different type...i think 1n60.....
I started off getting low voltages and refined it until i can get up to 28 volts out @ 500 ua.....not much power but i can run various small devices or charge batteries now. :)
It's all fun....i also tinker with the capacity versus inductance ect....teaches you alot!
Scotty.

jake 04-22-2012 07:11 PM

FM anyone?
 
@loadstone,

Have you ever tried power recovery with an FM station??

jake 04-22-2012 08:40 PM

Quote:

Originally Posted by xee2 (Post 189532)
@ jake

I calculated the field strength voltage 5 miles away from a 1,000 watt transmitter to be 0.03 volts per meter. This is a rough calculation but gives approximate value to be expected. You are getting much more out. I am impressed with your design. I worked several years as an antenna engineer developing very advanced antenna designs, so it takes a bit to impress me.

For a 10,000 watt transmitter this increases to about 0.10 volts per meter.

After I did the calculations the hard way, I found an online calculator that gives about the same answers:

Volt per meter and power density calculator


EDIT: A tuned antenna will suck up the RF energy much like an electronic vacuum cleaner, so I would expect your antenna to produce more than the ambient volts. It is actually possible to measure the lack of signal behind a tuned antenna which shows it has absorbed energy from an area much larger than itself.

Just noticed this edit:

Right now it does nothing to a radio when I plug hook up the secondary but I can still light the led.

One previous setup it was making the radio louder when I hooked it up. I think it was when I grounded it to the house ground but the led would just fliker every once in a while.

This is where the extra coil and ring capacitor come in to play. I dont want to change the wire length, coil hight or coil diameter. So all I have is capacitance and I have tried: a 3 turn 505pf variable air cap. A 112pf HV air cap. and a couple of other crystal radio/pocket radio caps and they just dont do much of anything across the secondary.

xee2 04-22-2012 11:54 PM

Quote:

Originally Posted by jake (Post 189623)
One previous setup it was making the radio louder when I hooked it up.

Your house radio resonator and the crystal set resonator are mutually coupled. See ... AM Radio with wireless Loop Antenna - YouTube

madhatter 04-23-2012 01:27 AM

The crystal radio project is to recover Teluric currents, not hertzian waves. This is why ground is THE most important part of the project.

recovering hertzian waves and magnifying them to power LED's etc.. is nothing new, novel but not what Eric was going for.

Diodes, 1N34A have a very low FW voltage, and a high 50V breakdown. 1N60 is nearly twice as high in forward voltage with a lower 40v breakdown, although the 1N60 is supposedly mfg to higher tolerances.

a ground impedance of 1ohm or less is going to be the biggest and for most an impossible requirement.

jake 04-23-2012 01:47 AM

Quote:

Originally Posted by madhatter (Post 189663)
The crystal radio project is to recover Teluric currents, not hertzian waves. This is why ground is THE most important part of the project.

recovering hertzian waves and magnifying them to power LED's etc.. is nothing new, novel but not what Eric was going for.

Diodes, 1N34A have a very low FW voltage, and a high 50V breakdown. 1N60 is nearly twice as high in forward voltage with a lower 40v breakdown, although the 1N60 is supposedly mfg to higher tolerances.

a ground impedance of 1ohm or less is going to be the biggest and for most an impossible requirement.

Yes, you are correct. However one can use the Hertzian waves to tune their secondary, just like we are doing with the function generator. LEDs make pretty good HF indicator lights.

So whats you take on my standing wave question? last page

madhatter 04-23-2012 02:06 AM

Quote:

Originally Posted by jake (Post 189668)
Yes, you are correct. However one can use the Hertzian waves to tune their secondary, just like we are doing with the function generator. LEDs make pretty good HF indicator lights.

So whats you take on my standing wave question? last page

Not sure I understand what you're after, could you explain a bit more?

Also this is going to be frustrating, but all leads will impact the L&C of the circuit, I found that by using the coil itself it's a better compramise then adding in wire length. the leads and LED also effect the circuit too, it's a big balance game.

jake 04-23-2012 02:53 AM

[QUOTE=madhatter;189674]Not sure I understand what you're after, could you explain a bit more?[Quote]

As far as the Standing wave. Should there be one along the lenght of the wire?


Quote:

Originally Posted by madhatter (Post 189674)
Also this is going to be frustrating, but all leads will impact the L&C of the circuit, I found that by using the coil itself it's a better compramise then adding in wire length. the leads and LED also effect the circuit too, it's a big balance game.

Yes, Yes, and Yes I noticed that.

A wise man once said "we were going to need a new set of tools to work with these new concepts" or something along those lines. Once I realized I could easily light an led I thought that it could make a handy dandy indicator. THEN..

I get my hands on a 10MHz function generator. I start testing and messing but lacking a fuctional ground I can only take my results as mere observations of a crystal radio and NOT a TRT. What did I learn....that leads are the enemy. Thats when I made the leap form FWBR to AV plug and that made all the difference. Thanks to all those who helped with that. No leads and 1 point of contact. That makes a nice little indicator. With that indicator I can touch the coil at any point. And it appears to make very little change to the resonant frequency. The change I do see is usually caused by me holding the AV plug. BUT I cant get the AV plut to light on a stick.:wall:

jake, jastermake @ yahoogroup

madhatter 04-23-2012 04:11 AM

[QUOTE=jake;189683][QUOTE=madhatter;189674]Not sure I understand what you're after, could you explain a bit more?
Quote:


As far as the Standing wave. Should there be one along the lenght of the wire?

jake, jastermake @ yahoogroup
I'm going to be a bit lazy here and point you to this, Standing waves and resonance : TRANSMISSION LINES it may help answer some questions, if you've got more after, let me know.

the length, are you referring to the physical wire length or the length of the coil? there is also the issue of electrical length. gets more involved with RF and transmission, esp here since C is no longer a fixed value.

xee2 04-23-2012 05:57 AM

Quote:

Originally Posted by jake (Post 189683)
As far as the Standing wave. Should there be one along the lenght of the wire?

For parallel resonator or self resonant coil:
When the resonator is at resonance there will be a standing wave on the inductor wire with a peak voltage measured across the ends. Note that this is an RF wave not DC. Best way to measure this is with scope using very small capacitor as probe. There will be multiple peaks if the resonator is resonating at a harmonic of fundamental resonator frequency.

jake 04-23-2012 06:15 PM

Oooops!!!
 
:confused: :confused: :confused:

So I went outside soldered into a ground wire and set to work. With 1 turn, 1/2" flat copper stock primary. Tried different arials, different hights, and so on and so on. Got it down to 1620(heard it on the radio 15' away) with a big aluminum salad bowl. , I went back to no terminal and put on my big fat 2 turn primary. Started testing with this when


A small white exlporer sticker on side said "Texas Communicat........." Could not read the whole thing. Pulled into my driveway waved nicely at me then drove off nice and slow....

There is a company called "Texas Communications" that runs communication services and it may have been one of their trucks. but still :confused: It did not feel right.

Did I break a rule?? FCC or other??

Function Generator signal level never went past 1/3. and was usually all the way down..

BK Precision 4017A, 10mHz, 10v(max) p-p into 50ohm, minium .25v p-p across my scope.

:whistle:

xee2 04-23-2012 06:52 PM

Quote:

Originally Posted by jake (Post 189753)
:confused: :confused: :confused:

So I went outside soldered into a ground wire and set to work. With 1 turn, 1/2" flat copper stock primary. Tried different arials, different hights, and so on and so on. Got it down to 1620(heard it on the radio 15' away) with a big aluminum salad bowl. , I went back to no terminal and put on my big fat 2 turn primary. Started testing with this when


A small white exlporer sticker on side said "Texas Communicat........." Could not read the whole thing. Pulled into my driveway waved nicely at me then drove off nice and slow....

There is a company called "Texas Communications" that runs communication services and it may have been one of their trucks. but still :confused: It did not feel right.

Did I break a rule?? FCC or other??

Function Generator signal level never went past 1/3. and was usually all the way down..

BK Precision 4017A, 10mHz, 10v(max) p-p into 50ohm, minium .25v p-p across my scope.

:whistle:

You broke no rules. He probably pulled into your driveway by mistake and then realized he was not where he should be.

jake 04-23-2012 07:12 PM

Just remembered there is also a strong resonant point at 7MHz that I played with. Does this change anything?

xee2 04-23-2012 08:32 PM

Quote:

Originally Posted by jake (Post 189764)
Just remembered there is also a strong resonant point at 7MHz that I played with. Does this change anything?

I doubt that your signal generator will put out enough power to interfere with anything unless you have neighbors within a 100 feet and then they would need to have a radio tuned to the frequency you are using (unlikely).

madhatter 04-23-2012 09:25 PM

The FCC has no sense of humor, be careful.
wiki link on FCC broadcasting regs
Title 47 CFR Part 15 - Wikipedia, the free encyclopedia

20dBm = 100mW is the maximum allowed, also there is limits on antennae length. ground and above ground total to 3meters.

jake 04-24-2012 05:58 AM

Im Back!
 
So before I was freaked out earlier. I was tring to figure out the standing issue I have.
@ mad, I like it when you lazy.

So what I really wanted to ask was why is there only a partial wave along the coil at resonance? With a 1 turn primary I get 1/4 of a wave along the entire coil. Meaning the the can has highest "potential and the potential along the coductor goes down to nothing as you approach ground.

However a few days ago I had 1/2 wave at resonance when I was using my primary instead of a 1 turn copper strip. Meaning highest potential on terminal, the 5 turns on in the middle of the coil had nothing and voltage went back up(actually -) as you approached the ground.

I had just got my primary back on when. I pooped my pants.. Spent the rest of the day at FCC.. and wiki.

What did I learn there: 2mHz-3.5mHz is wierd and is allocated to maritime, ship to shore, and other , but the coast guard uses it as well and I can't forget 2.1735MHz mobile distress and calling frequency.. I was all over that one today. With the right termination/salad bowl. I learned I can keep it under 2MHz and still play as long as I keep it turned down all the way..

I used a FWBR made from SF35s and SF37s diodes. Across the DC of the FWBR I used a 100pF cap. Powering the function generator at 1.8MHz the max I could get was 90mA straight across a DMM out from the rectifier. How do I go from that to "milliwatts of DC input power to the final RF stage"?


time to do the pots.

xee2 04-24-2012 03:22 PM

Quote:

Originally Posted by jake (Post 189807)
and voltage went back up(actually -) as you approached the ground.

You must have had a bad ground connection. Ground should never have a voltage on it (it is the reference for all other voltages).

xee2 04-24-2012 03:30 PM

Quote:

Originally Posted by jake (Post 189807)
I used a FWBR made from SF35s and SF37s diodes. Across the DC of the FWBR I used a 100pF cap. Powering the function generator at 1.8MHz the max I could get was 90mA straight across a DMM out from the rectifier. How do I go from that to "milliwatts of DC input power to the final RF stage"?

You need to measure imput impedance of antenna to determine how much power is going into it. But it will look like like a small capacitor. To get power into the antenna you need to make a matching network to convert generator impedance to complex conjugate of antenna impedance. As is, 90% of power appllied to your wire antenna is being reflected back to generator (less than 10% is going into antenna). So the amount of power your antenna is readiating is very small.

jake 04-24-2012 04:11 PM

Quote:

Originally Posted by xee2 (Post 189826)
You must have had a bad ground connection. Ground should never have a voltage on it (it is the reference for all other voltages).

Awesome.. Thats why I went outside and soldered directly to decent "ground". Did not stay out long enough to prove it to myself.

jake 04-24-2012 04:24 PM

Quote:

Originally Posted by xee2 (Post 189827)
You need to measure imput impedance of antenna to determine how much power is going into it. But it will look like like a small capacitor. To get power into the antenna you need to make a matching network to convert generator impedance to complex conjugate of antenna impedance. As is, 90% of power appllied to your wire antenna is being reflected back to generator (less than 10% is going into antenna). So the amount of power your antenna is readiating is very small.

I was hoping for more answers like this...

BUT what the #?*! did you just say..

I never wanted to transmit.. never planned on it.. still dont want to. I'm more of a receiver.

Is "very small" enough to make a radio 15' away scream like a banchee. By scream like a banchee I mean, completely drown out the local station that was coming in loud and clear? And boost the volume?

I have absolutely no reference of radiated RF and its capabilities. So I appreciate the replies.

jake:whistle:

xee2 04-24-2012 04:42 PM

Quote:

Originally Posted by jake (Post 189834)
I was hoping for more answers like this...

BUT what the #?*! did you just say..

I never wanted to transmit.. never planned on it.. still dont want to. I'm more of a receiver.

Is "very small" enough to make a radio 15' away scream like a banchee. By scream like a banchee I mean, completely drown out the local station that was coming in loud and clear? And boost the volume?

I have absolutely no reference of radiated RF and its capabilities. So I appreciate the replies.

jake:whistle:

At 15 feet you are coupling to the receiver directly not picking up the RF radiation. A wavelength at 1 MHz is 1000 feet so 15 feet is only a few percent of a wavelength away. This is called near field coupling and is very strong.

jake 04-26-2012 12:17 AM

Really 90%
 
Quote:

Originally Posted by xee2 (Post 189827)
You need to measure imput impedance of antenna to determine how much power is going into it. But it will look like like a small capacitor. To get power into the antenna you need to make a matching network to convert generator impedance to complex conjugate of antenna impedance. As is, 90% of power appllied to your wire antenna is being reflected back to generator (less than 10% is going into antenna). So the amount of power your antenna is readiating is very small.

http://i1082.photobucket.com/albums/...tProcedure.jpg

In the bottom diagram 90% is being reflected to the generator???

xee2 04-26-2012 01:01 AM

Quote:

Originally Posted by jake (Post 189991)
In the bottom diagram 90% is being reflected to the generator???

It is hard to tell from diagram. I was assuming you were just connecting a wire to signal generator. In this case there is a whole circuit attached. But I suspect that most of the energy is being reflected back into the generator. Getting an electrically small antenna (length only a small fraction of a wavelength) to radiate all of the power being fed to it requires much work. When the length gets to be 1/4 wavelength the antenna impedance will be close enough to 50 ohms to radiate most of power. But less than than 1/4 wavelength will reflect most of the power fed to it from a 50 ohm source.

If you are tuning with the set up in diagram, be aware that the frequency is going to be effected by the loop attached to the generator. I think it would be better to use a short wire well away from the receiver resonator to transmit with when tuning the resonator.

dR-Green 04-26-2012 01:26 AM

Quote:

Originally Posted by Web000x (Post 188746)
I don't think I've seen an extra coil on your setup, or have I?

No you haven't, not yet. I suppose I could make an extra coil first and test it on the spiral :thinking:

xee2 04-26-2012 01:34 AM

Quote:

Originally Posted by xee2 (Post 190002)
I think it would be better to use a short wire well away from the receiver resonator to transmit with when tuning the resonator.

Being close to the resonator will also effect tuning. I recommend sweeping the frequency to see where it resonates, adjust, move away, sweep frequency to see where it is resonant, .... etc.

jake 04-26-2012 01:47 AM

Quote:

Originally Posted by xee2 (Post 190002)
It is hard to tell from diagram. I was assuming you were just connecting a wire to signal generator. In this case there is a whole circuit attached. But I suspect that most of the energy is being reflected back into the generator. Getting an electrically small antenna (length only a small fraction of a wavelength) to radiate all of the power being fed to it requires much work. When the length gets to be 1/4 wavelength the antenna impedance will be close enough to 50 ohms to radiate most of power. But less than than 1/4 wavelength will reflect most of the power fed to it from a 50 ohm source.

If you are tuning with the set up in diagram, be aware that the frequency is going to be effected by the loop attached to the generator. I think it would be better to use a short wire well away from the receiver resonator to transmit with when tuning the resonator.

-1 turn primary flat 1/2". in series across the Function generator
-20 turn secondary 29.5-30.0 meters. about 2" above the secondary, same diameter
-Coil was most active at 2000kcycles. It lit an av plug the brightest at the greatest distance.

Considering these three observations, and considering the 20 turn secondary as the antenna;

Can I conclude the coil is acting like a (1/4 lamda) 150m antenna? (i.e. I have electrically lengthened the 30m wire I used in the secondary)

xee2 04-26-2012 02:45 AM

Quote:

Originally Posted by jake (Post 190007)
Can I conclude the coil is acting like a (1/4 lamda) 150m antenna? (i.e. I have electrically lengthened the 30m wire I used in the secondary)

It is possible but there is no way for me to tell if that is happening. But the resonant frequency is going to change when you disconnect the generator if the generator is tightly coupled to the resonator. I think your objective is to get the receiver tuned to the correct frequency, not to make a transmitter tuned to the correct frequency.

jake 04-26-2012 04:00 AM

Quote:

Originally Posted by xee2 (Post 190013)
I think your objective is to get the receiver tuned to the correct frequency, not to make a transmitter tuned to the correct frequency.

You are correct:thumbsup:

and on the way there I'm disecting each component.

I do not know what frequency the secondary should resonate as it is shown in the diagram. What part the secondary plays in the TRT I do not know. I think Eric may be the only one. But this is not a TRT, just yet.

So I am looking at the coil from all angles. How it was a radiator in this case study, not exactly what I was expecting but Ill take what I can get.

When excited @ 2000kcycles it radiates quite readily but at 1620 not so well:( . Same goes for receiving I thought...:confused:

'CAN' or Beer can/ dr pepper can, is the standard end termination for the Crystal Radio Initative. Dollard recommended it and I think those building are also using it in testing.

I need a lot of 'CAN' to bring it down to 1620. But how much 'CAN' will be provided by the extra coil, I do not know. The two split rings in the final design of the TRT will allow for some adjustment. Of 'what' is still to be determined. So much I do not know.


As far as the 150m question I was just trying to figure out why it ended up that way since I was only using 30m of wire. But I think I got that part figured out.

:thumbsup:

jake 04-26-2012 04:48 AM

Trt
 
The final product.

by EPD
http://i168.photobucket.com/albums/u...former0011.jpg

I do not know whos site this picture is hosted on but, I hope you don't mind that I used it here. If you do please let me know.

xee2 04-26-2012 05:31 AM

@ jake

Wow, that looks complicated.

To lower your frequency you need to add parallel capacitance to the coil. Probably about 5 to 10 pF. You can make an adjustable capacitor with two sheets of copper overlapped with insulator in between and held together with a clothes pin.


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