ฝัง
- เผยแพร่เมื่อ 29 ส.ค. 2023
- The most common crystal radio question I get is about the size of the coil. We go over several pipe / wire sizes and discuss the tradeoffs.
Video: Best/Easiest DIY Crystal Radio - No Batteries, No External Power (4K)
• Best/Easiest DIY Cryst...
This is a very easy to use, single layer coil calculator:
www.circuits.dk/calculator_si...
VIDEO: Crystal Radio & Resonant Coil Design (4K)
• Crystal Radio & Resona...
Q: Does my coil have to be exactly like yours?
A: Yes and No. For this style of radio it should have the same inductance of around 531 uH (measured resonance at 1MHz)
The following will get us to 531 uH (all equivalent, but efficiencies differ, bigger is better)
Bigger diameter is more efficient, but shorter.
Shorter coil means less tuning/fewer stations.
Longer coil is harder to make a wiper and has resistance.
Bigger wire is better for tuning, BUT you need more turns, longer coil. (Fine wire can be a bear to tune)
==================================================
These are different ways to get 531 uH by changing tube/wire sizes.
The wire I use is .036" or 0.91mm (19 AWG), which is bigger and easier to tune.
Toilet paper tube (weak): 46.7mm OD diameter (measured), 100mm long wire diameter INCLUDES the enamel coating.
19 AWG = .036", 0.91mm === length: 8.65" or 219.6mm and 244 turns (rounded up)
22 gauge = 0.6438mm === length: 4.74" or 120mm and 187 turns
24 gauge = 0.5106mm === length: 3.2" or 81.2mm and 159 turns
One & a half inch PVC plumbing pipe (blue): actual = 1.9" or 48.26mm OD
19 AWG = 0.036", 0.91mm === length: 8.4" or 211.5mm and 235 turns (rounded up)
22 AWG = 0.6438mm === length: 4.5" or 114mm and 178 turns
24 AWG = 0.5106mm === length: 3.1" or 77.4mm and 152 turns
Two Inch PVC plumbing pipe (blue): actual = 2.375" 60.325mm OD
19 AWG = 0.036", 0.91mm === length: 5.74" or 145.7mm and 160 turns (rounded up)
22 AWG = 0.6438mm === length: 3.22" or 81.8mm and 127 turns
24 AWG = 0.5106mm === length: 2.25" or 57 mm and 112 turns
Two & a half inch PVC plumbing pipe (blue): actual = 2.875" 73.025mm OD
19 AWG = 0.036", 0.91mm === length: 4.3" or 109mm and 120 turns (rounded up)
22 AWG = 0.6438mm === length: 2.5" or 63.6mm and 99 turns
24 AWG = 0.5106mm === length: 1.79" or 45.5mm and 89 turns
Three Inch PVC plumbing pipe (blue): actual = 3.5" or 89.8mm OD
19 AWG = 0.036", 0.91mm === length: 3.25" or 82.5mm and 91 turns (rounded up)
22 AWG = 0.6438mm === length: 1.97" or 50.1mm and 78 turns
24 AWG = 0.5106mm === length: 1.44" or 36.7mm and 72 turns (too short!)
The Cub Scout Book from 1963 says, "TUNING COIL Wind wire tightly around a dry shellacked cardboard tube about 1 1/2" across and 6" to 7" long Shellac all over again. When dry, fasten it to baseboard at both ends. Put in washers or blocks to keep it from touching the board." The diagram says "22 gauge enameled wire". With these specifications, they are targeting between 1250 uH (6") and 1470 uH of inductance. - วิทยาศาสตร์และเทคโนโลยี
This is a very easy to use, single layer coil calculator: www.circuits.dk/calculator_single_layer_aircore.htm
VIDEOS: Crystal Radio & Resonant Coil Design (4K) th-cam.com/video/Fw9eb-aB-XU/w-d-xo.html
Best/Easiest DIY Crystal Radio - No Batteries, No External Power (4K)
th-cam.com/video/fLVCqZGpv3U/w-d-xo.html
@tsbrownie: Thank you for the link. From a different communication. This sort of technical information is much more detailed than many video makers will share, but it's extremely helpful to beginners. Thanks for taking the extra time and effort.
The 160 Meter ham band is just a little higher in frequency than the AM Broadcast band. It's from 1.8 mHz to 2 mHz. Some hams communicate there using the AM mode, mainly at night, and maybe using only a few hundred watts of power as opposed to the commercial broadcasters who can use kW of power.
Also, that band won't be as well populated as the AM Broadcast band. A few Crystal radio builders might find it a novelty to try getting their crystal radio to tune up there. Mostly hams will use morse code and single sideband voice there. Only AM can be inderstood on those frequencies.
In passing hams can also now use frequencies that are below the AM Broadcast band. Crystal radios generally won't hear those few hams who go there. Their transmitting power is limited down there.
I think maybe you already gave some information about short wave listening on frequencies far removed and well above the AM broadcast band. Some prople are avid short wave listeners.
my fathera always tried to make one as a child this video is going to make me try to make one with him ty
Let me know if you have questions. The following video explains how to build this type of crystal radio.
th-cam.com/video/mt-s7pf-U5Q/w-d-xo.html
@@tsbrownie tysm
GREAT INFO THANKS
Built 3 radios so far, none have worked ... i'll get this right one day! Thanks for the video.
Do you have AM stations in your area? That can be a problem. I have a video on what to look for when they don't work. Google "tsbrownie my crystal radio does not work"
@@tsbrownie Yes, WWL 870am is near me and i should pick them up with no problem. I think maybe i didn't get the specs right when i ordered all the components for my builds.
@joel6221 The diode, earphone, and coil are key. Get those right, and it's going to work. Watch out for fake 1n34a diodes. I have a video on that too.
Hi, if you are using one of those crystal earphones put a resistor across it.
47k to 100k not critical. It removes charge building up.
I made many crystal radios but there is a problem with my house grounding, it has 50hz hum making it barely hear the station
You should NOT be using your house electrical grounding! It is very dangerous, especially if there's any ground loops or other in your wiring/appliances. You need a separate ground rod. In fact, when I lived in apartments or otherwise could not have a ground, I just strung up a second antenna and that often works as well (and sometimes better.)
Are there any quick cheat graphs floating around where you can look at the gauge of wire, scroll across to the pipe size and determine the number of turns required? Similar to the mutiplication cheat graphs we used in school to learn multiplication.
There are the online calculators I list in the description. I haven't seen any tables.
Could you pour some kind of resin over the top of the coil, and sand it, to produce a smooth, non rough surface to move the wiper over smoothly for less wear and more precise tuning?
I don't have that skill, but if someone does, that should work. It would be cool to have a coil embedded in a clear resin block! Wrap it on clear glass, do the resin thing. Cool! And the smoothness would very likely make tuning smoother.
Is there an online guide to building coils that shows this relationship if someone uses an odd sized form or wire? Also, I have never seen any recommendations for using aluminum wire in case you were to unwind a transformer with aluminum wire to use on a crystal radio coil?
There are a lot of calculators online, most are not easy to use. I found a good one the other day, let me see if I can find it again.
This is a very easy to use, single layer coil calculator: www.circuits.dk/calculator_single_layer_aircore.htm
@@tsbrownie Thank you sir.
Do you happen to be from the Philippines?
I am American.
What is the difference if you use silver wire?
For the same diameter wire, the coil could have lower resistance than copper, but the inductance should be the same.
I built a Radio just as your video shows and other are telling me this is wired wrong. To look at other crystal radios.
I show radios that are easy to build and work well. Not always the highest tech. Can you give me links to the videos of the people who are telling you it's wrong? I'd like to learn how they did it.
I have done a bit of research and the only thing I see is that there is a model that is set up like yours but for the ground wire crosses over to connect just before the resistor. The left end of the coil wire is not shown, so I don't know if its open or not.
But your design makes more sense to me. The circuit runs from antenna to ground. BTW I may have figured out the issue. Its also one that you may want to do a video on. There is only a couple of places I found the info and one was a video that does not come up in my normal search. The Piezo Electric ear piece that I have is made in Taiwan.
These seem to have about a
35% fail rate. The Japan made ones seem to be better built. I also found on Amazon where I bought mine and it is a Taiwan made ear piece that they now have one from Taiwan that says "upgraded, brass diaphragm soldered on both sides. "
The one video I found shows them both the Taiwan and Japan made versions taken apart or cut apart. The Taiwan made is soldered on the back of the diaphragm and and glued on the front and the two plastic ear pieces are glued together. The thing that was the issue is the glue. It seems that sometimes the glue is too much and glues down the diaphragm.
He shows how you can drill a hole in the back and poke it with a pin to try to loosen it. He also said he got the percent when someone ordered 100 of them for a boy scout project type thing and that is how many did not work. I will leave a link to the video and the one about the ground going over to the resistor. I would like to know if the coil on that model is left open.
Here is a link to the questionable ear piece I bought. BTW I have two new upgraded ones coming in. www.amazon.com/dp/B071JWPTT9?psc=1&ref=ppx_yo2ov_dt_b_product_details
Link to the video of the alternate wiring of crystal radio.
www.sciencebuddies.org/science-fair-projects/project-ideas/Elec_p014/electricity-electronics/crystal-radio
Here is the link to the bad earphones from Taiwan.
th-cam.com/video/yBxo8CaY4HY/w-d-xo.html
BTW I was not accusing your wiring of being wrong, just passing on what some had replied to me, that the wiring was wrong and that I should look at other videos.
@@tsbrownie
@@jaybabcock4557 Thanks for all the good info. I don't know why, but youtube did not notify me of your response. They seem to be kind of random about it.
I just want to make a working version. I put up a 100 foot line antenna but it did not do what I wanted it to. I think because it was only about 6 feet off the ground. I need to put it up higher. But I need a warm spell to do that. LOL@@tsbrownie
@@jaybabcock4557 6 feet is not too bad for height and 100 feet long is more than twice mine! Higher is better so someone does not run into it. You might already know this, but just in case... Orientation makes a difference. Bare wire or enameled is preferred. Also, make sure your ends are well insulated and you don't coil up any spare wire.