Yep. Now your starting to get it
Although there are a number of other problems too. I can see multiple issues with just about every part....
For example, the thickness of your wire is like using a very large fire hose in your bucket example.... I don't know exactly how its going to mess with the circuit, but it will. That is another reason rimstar uses thin wire. I could be wrong here, but if I wanted to get MHZ range (think about that for a moment. Millions of oscillations per second. Thats really really fast! oscillation's every few nano seconds!) Id be reaching for thin wire for lower inductance. A quick check of the induction of 2 different 3 inch nail's validates me. I got a higher reading from the thicker one.
That makes sense. If you connect a fire hose to a garden hose water spout, the water molecules will move much slower. So the thicker the wire gauge, the slower the oscillatory frequency.
Just try stuff. Its a great way to learn. I teach myself stuff that way daily. Just dont expect it to work every time. Like I just did with 2 nails and an induction meter. Worked, learned something. Or the time I tried to make a FET with a spark gap in a cup-cap. It didn't work out exactly how I wanted, I got an electrically adjustable spark gap, I also set a few cup-caps on fire... Failed, but I learned stuff from the failure, and gained a better understanding for next time. There are a few do's and Don'ts though.
Okay.
Do have some inkling what you are doing. If you throw random parts together in a random fashion, it will either work or not work. Either way you will have no idea why and learn nothing. This is why scientist tend to play with only one variable at a time. As well as fully understanding a "Control" which in this case would be a simple crystal set.
Oh I think I get it! The control is the simple MW crystal set, and improvements on it are the variables.
Do ask for help if you get stuck, But Don't expect someone else to fix every part of a circuit for you. Which is sort of what you are doing here. Inventing your own parts is for after you got one working. If you never made one before, and need to use home made parts. Find someone thats done it before, with sucsess, and copy that first. You will learn stuff. Then you will have a much better idea why the parts you are inventing are not working.
Okay, so if my home made part has a different design from a home made part that some one else built, it would be good to have a way to measure the inductance or capacitance and then use some simple maths to calculate the resonant frequency.
Don't just assemble random parts, unless you have some idea what the results will be. No one will help you. I tried that once too. Got a similar response to you. Now I know a bit more, I can see why. Its like trying to teach someone to read, when they only know half the alphabet.
Okay.
Do do some homework, we can help, but not teach you from scratch, there are tons of great resources online that can do that better anyway. Like rimstars channel, and many many other sites.
Yeah, I learned more about how inductors, capacitors, resistors, and tank circuits work at the electron level on Rimstar's channel than I ever learned in my physics class.
Do look at what others have done before you. You will learn stuff.
Makes sense. What others have working I should get it working first instead of making stuff up.
Don't get testy with people that are donating their time to help you. We don't have to help. We dont get paid, or any other benefit, other than a warm fuzzy feeling. If you don't listen we wont have time. Sometimes its hard to convey full meaning without facial expression or voice tone. Thats what the emotes are for. "You stink", is very different to "you stink
" which is clearly a jest.
Makes sense.
Do be able to measure stuff well. If your going to self teach, I recommend some decent meters. Or even better learn to make and calibrate your own. My first lesson in electronics, from my Uncle, was whats inside a multimeter and why its there, what it does... Analog is best for this. Its all you need. There are guides online for making a cap meter or induction meter. You can also get some half decent ones on ebay for really cheap.
I already have an analog multimeter, and it doesn't measure inductance and capacitance, but I can make my own your saying!
Well I read some instructions on how to build home made capacitance meter and its not as easy as I hoped, so I think I will use math to find out the inductance of the coils since the math to find out the inductance of the coils is not that hard, and then when my coils and capacitors allow me to tune to a station, when I know the station's frequency and I know the inductance of the coils I can solve for the value of the capacitor.
Don't let frustration beat you. Its going to happen, regularly at first. Take a break, do other stuff. go for a walk. Come back to it later and something obvious will likely jump out at you. Failing that study working ones, with proven design and see whats different. As Davenn and a few others have suggested
Okay.
Don't use foil for a fuse. Steve will ban you
I've done it, half the people on the forum may have at some time, but we dont talk about it in public. Thats a great way to get sued. (*Disclaimer* I personally recommend inline fuses on all projects) 3 inch nails and bolts are not fuse's ether.
Okay.
Do use proper circuit symbols when possible. Its horribly confusing if you dont. Also consider, you had me trawling through google images trying to work out what component that was... I'm still learning a lot of switching components....
Okay.
I think your should be getting the point by now. I wont go on.
Okay I think I'm getting it!
Go make the rimstar model. then when you have that working. You can do the maths to work out how much you need to change values for your parts. Then, if you still think it will work. and you can make parts that sensitive. give it a go, and people here will be much nicer to you. But we cant teach you to read write and spell well, until you learn your ABC's
so to speak. Really we'd rather just help you with a single thing at a time. You just turned up to a how to speak english room, and asked us to help decipher the Koran. Except your copy is a cheap knock off, and has the pages in the wrong order.... We are all going nowhere, fast.
Okay, I'll go make the RimStar model, EXACTLY as he made it, to guarantee that it will work, and after I have it working, I can try different combinations of inductors and capacitors to see what works.
I was worried that I would be too clumsy the wind all the coils on such a small coil form, but RimStar makes it easy with the masking tape technique! I assume that duck tape wouldn't work for this, because duck tape leaves too much residue, so I have to buy masking tape.
Calculations for air core inductor:
, where L is the inductance in Henries, l is the length in meters, A is the cross sectional area in meters squared, N is the number of turns, and mu is the relative permiability constant of air.
The relative permiability constant of a vacuum is 1. The relative permiability constant of air is 1.00000037
RimStar's first coil has 90 turns around a toliet paper roll of about 3.5 inch diameter and length of about 5 inches long.
The area of a circle is pi*(r squared).
Half the diameter is the radius. So the radius is 1.75 inch. We must convert the distances into meters. I used an online converter.
1.75 inch = 0.044450m 5 inch = 0.12700m
Once you find the inductance for one coil, you multiply it by (N squared).
The cross sectional area of one coil if it was the whole length of the toliet paper roll therefore is (1.00000037 )(1) [ pi * (0.044450m squared) )/ (0.12700m) ] = 0.048875 Henries
1 micro Henry= 1.0E-6
0.048875 Henries / 1.0E-6 = 48,875 micro henries
I found a website selling AM antenna ferrite loop sticks that have about 680 micro henries.
So I think I did something wrong in my calculations.
I think I found the problem. The length is supposed to be for each coil, not the length of the inductor.
So it appears that if I used a moving box to wind 20 coils on, that would be WAY TOO MUCH inductance.
Well so I will say that each coil has length of the toliet paper roll divided by number of coils, assuming that coils are evenly spaced.
So that gives a length per coil of 0.12700m/ 90 = 0.001411 m
So I will try the equation again with the new length. (1.00000037 )(1) [ pi * (0.044450m squared) )/ (0.001411m) ] = 4.399 henries
That's an even less reasonable answer!
Oh, I think I know the problem, my equation is approaching dividing by zero and that has some strange things happen... It has infinite inductance from an inductor that has a coil length size approaching 0. A number divided by a value approaching zero will lead the result to approach infinity.
The cause of the approaching dividing by zero is that my coil length is too small. So the equation must mean THE LENGTH OF THE WIRE IN EACH TURN, rather than the actual physical space that each coil takes up in length on the paper towel roll up and down on the roll.
The length of the wire in each turn, assuming no coil spacing, is the circumference of the coil.
Circumference of a circle = 2*pi*r
Circumference of RimStar's inductor for each coil = 2*pi* 0.044450m=.27928 (m^2)
So now the inductance of each RimStar coil is (1.00000037 )(1) [ pi * (0.044450m squared) )/ (.27928) ] = 0.022305 henries
0.022305 henries / 1.0E-6 = 22, 305 micro Henries per coil.
Still too much!
Wait, I think I used the wrong permiability constant. I think I was supposed to use the permiability constant instead of the relative permiability constant.
So now the inductance of each RimStar coil is (1.2566375E −6)(1) [ pi * (0.044450m squared) )/ (.27928) ] = 2.8029 E -8 henries
2.8029 E -8 henries / 1.0 E -6 = 0.028029 micro henries
That's more like it!
(0.028029 micro henries)*(90 turns)=2.52269 micro henries
The ferrite loop stick has a multiplier of about 10-100 for the ferrite core. So (2.52269 micro henries) (100) = 252.269 micro henries.
So therefore, the 680 micro henry ferrite loopstick has turns found by solving this equation:
252.269 micro henries / 90 turns = 680 micro henries / x turns
252.269 x = 90*680
252.269 x = 61,200
x = 61,200 / 252.269
x = 242.5 turns
So since the inductance on RimStar's inductor is not that much compared to the ferrite loopstick, that's why he must use such a large variable capacitor. Compared to an AM/FM radio can use the same variable capacitor as long as the AM ferrite loopstick has enough inductance.
Well so after I get RimStar's crystal set to work, I could increase the inductance of the inductor to allow a smaller variable capacitor to be used by placing a big iron bolt inside the toliet paper roll.
I think a steel rod from an unused steel cymbol stand will work.
Time to start ordering parts!
So since I'm using magnet wire, I should order sand paper to sand off the enamel at the connections.
RimStar's crystal set doesn't even use alligator jumpers, and just uses magnet wire with sanded off enamel at the connections and masking tape to hold the connections together so its cheaper!
So I don't need to buy alligator jumpers.
So all I need to buy is magnet wire, masking tape, and sand paper.
The ill:
sandpaper $1.75
http://www.amazon.com/3M-Aluminum-S...ref=lh_ni_t?ie=UTF8&psc=1&smid=A2BBUA7LL95L5R
masking tape $1.37
http://www.amazon.com/Office-Impres...ref=lh_ni_t?ie=UTF8&psc=1&smid=A1RDYXN1JW1DJR
magnet wire #22 AWG $7.90
http://www.amazon.com/22AWG-Solid-I...id=1367946139&sr=1-1&keywords=magnet+wire+#22
Also included guitar output jack for $1.95
total before shipping and handling: $13.41
total after shipping and handling: $28.03
On second thought, I'll just buy as much as I can from the local hardware store except the guitar output jack so I don't have to pay for shipping and handling.
On third thought (if that's even a word), I'll buy the sand paper and masking tape this week, buy the magnet wire next week, and buy the amplified PC speaker from the second hand store to steal semi conductors from on the week after that. This is so that my weekly allowance that my dad gives me is sufficient without having to ask for more until I get summer job.
On fourth thought (if that's even a word), I already bought the sand paper and masking tape today, and if I build a fox hole version of the RimStar crystal set I don't even need to buy a diode, resistor, transistor, or guitar output jack, so the only thing left to buy is the magnet wire for $5.
As the diode I would be using a blued razor blade (already have an old dirty rusty razor blade, I just need to blue it in the gas stove in the kitchen) connected to a half inch long piece of mechanical pencil lead as the point contact rectifier.
As the resistor I would be using an inch long piece of mechanical pencil lead.
As the output jack, the output wire leads are connected to a guitar cable with masking tape. The ground wire is connected with masking tape to the ground (outer part) of the cable jack. The hot wire is connected with masking tape and a single tiny alligator clip to the exposed hot wire on the inside of the cable by unscrewing the plug off of the cable enough to expose the hot wire. Just need to buy a few tiny alligator clips for a dollar.