Crystal Radio--Ferrite Coil Model #2 (4K)

Рет қаралды 2,413

Күн бұрын

I built a ferrite coil crystal radio from an internet design that worked poorly (I don't recommend building it). I recycled it into this second attempt, using a different winding scheme that worked well on an air core variable cap radio design. I recalculated the necessary turns to achieve the necessary inductance/tap and remade it. I'll show you the result.
I realized I was not clear with the wire sizes. The original ferrite was wrapped with 32 AWG (0.2mm) == 195 uH, the blue air coil was wrapped with 20 AWG (0.8 mm) == 205 uH. The second ferrite was wrapped with 24 AWG (0.55 mm) == 205 uH. Why did I change to 24 AWG? Turns out the 20 AWG wire is too wide and would not fit on the core.
MATERIALS
- Ferrite Rod 100x10mm, manganese zinc magnetic permeability 1K
- 2x hold down blocks
- 32 AWG wire 0.2032mm; Windings: 20/30/80
- Resistor 10k-40k ohms
- Variable cap: 0 to 400 pF or 0 to 500 pF
- Variable cap mount
- Brass washers
- Stainless screws
- Crystal earphone (piezoelectric)
- 1N34a diode3D
Print Ferrite bar holders www.thingiverse.com/thing:652...
3D Printed Mica Variable Capacitor Mount www.thingiverse.com/thing:652...
TOOLS
- Screw driver
- Knife
- Sandpaper (small piece, fine)
- Hand drill for screw holes
- (Optional) Soldering iron, solder
ANTENNA & GROUND
- Antenna are just a long piece of wire (I use scrap wire from old transformers). The longer the better.
- Try different lengths and orientations (vertical, horizontal)
- A good ground helps. A wire to a ground rod is good. Metal water pipes also work well.
NOTES:
- The resistor is necessary to get the best sound from these "new" crystal earphones. The new ones are piezoelectric and have lots of capacitance. Without the resistor the charge builds up then discharges so you get constant "static" sounds. The resistor bleeds off charge so you get louder, and much clearer sound.
WARNINGS:
- Never connect radio to any source of power. Not house current, nor batteries, nothing!
- Never use the radio during lightning storms.
- Never run an antenna over or near power lines.
- Disconnect antenna and put lead outside when not in use.
- Never ground to electrical items, plugs or similar.
- If you don't know, don't do it.
OSCILLOSCOPE USED:
$25 Color Oscilloscope! The Incredible DSO138 (4K) • $25 Color Oscilloscope...
Using The $25 DSO138 Oscilloscope - Joule Thief & Freq Generator (4K) • Using The $25 DSO138 O...
INTERESTING LINKS
- Knob For Variable Capacitor & Similar (D & Round Shaft Versions) www.thingiverse.com/thing:633...
- Knobs for capacitor tuned crystal radio. www.thingiverse.com/thing:619...
- Air Core: www.circuits.dk/single-layer-a...
OTHER CRYSTAL RADIO VIDEOS
- Popular Crystal Radio Design That Does Not Work • Popular Crystal Radio ...
- Good Crystal Radio Connection Points • Good Crystal Radio Con...
- My Crystal Radio Does NOT Work (FIXES for common problems) • My Crystal Radio Does ...
- Crystal Radio Fake 1N34A Diodes! Easy Test (4K) • Crystal Radio Fake 1N3...
- Crystal Radio DIY Cat Whisker--Wood, Brass, Stainless (4K) • Crystal Radio DIY Cat ...
- Crystal Radio Cat Whisker--Super Upgrade! • Crystal Radio--Cat Whi...
- PSA: Crystal Radio Coil--Bad Plastic Pipe Pt 3--Type That DOES NOT Work! • PSA: Crystal Radio Coi...
- Popular Crystal Radio Design That's a Waste of Time - And Why • Popular Crystal Radio ...
- Connect DC Amplifier to Crystal Radio • Connect DC Audio Ampli...
- Crystal Radio, Capacitive Tuning - WORKS GREAT! • Crystal Radio, Capacit...
CHAPTERS
00:00 Intro
01:26 The design
03:21 New coil
04:20 Old vs New
05:09 Origin story
05:37 Parts dimensions
05:49 Set up finished & compare old & new
07:26 On the scope & conclusion

Пікірлер: 24

@tsbrownie 2 ай бұрын

I realized I was not clear with the wire sizes. The original ferrite was wrapped with 32 AWG (0.2mm) == 195 uH, the blue air coil was wrapped with 20 AWG (0.8 mm) == 205 uH. The second ferrite was wrapped with 24 AWG (0.55 mm) == 205 uH. Why did I change to 24 AWG? Turns out the 20 AWG wire is too wide and would not fit on the core.

@junkmail4613 2 ай бұрын

75-year-old retired double E. I enjoyed your video. I also built a crystal radio back in 1963 with similar components. I was 20 mi from New York City, so WABC (50 kilowatts) could be received with only a headphone and a diode. Many memories thank you very much. Ten little indians (below) reminded me of 60 foot high tree I'd never have climbed 150 feet away from my house, to string an extremely powerful antenna to my bedroom window. It was great for a kid with no money to listen to night time radio on the sly. With no lightning arrestor, my Dear-ol'-Dad would have had a cardiac had he known. Kids are so crazy!!! I loved him.

@tsbrownie 2 ай бұрын

Thanks for sharing. I did the diode radio thing as a kid too. It was like magic. I repeated it recently. (Diode Radio) World's Simplest Radio kzfaq.info/get/bejne/o9JymaR6xJuZfZ8.html

@migalito1955 2 ай бұрын

Thanks, I almost indepently assembled a similar ferrite core crystal radio that had little sensitivity. This one wins hands down, but I'll give the air core a go instead.

@tsbrownie 2 ай бұрын

It seems that ferrite cores and variometer based radios are not suitable for unamplified, unpowered radios. Contesters use air cores and now I see why.

@t1d100 2 ай бұрын

I am so pleased that you 1) repurposed the board and 2) continued your investigation of the ferrite core. Kudos and atta-boy! How counter-intuitive and amazingly interesting to discover that the air core is sooo much superior. I am glad that you will repurpose the wood base, yet again. I understand that 3D printing a base is super convenient, but I find it cold and barren of nostalgia. Even the termination thread on the winding is better than glue, or tape, in that regard. And, I like the "ANT" and "GND" labels, stamped in previous boards. I guess I am just old and sentimental. Either that, or I am young, hip and really into steam-punk... grins... Yeah, I really love the solid wood base (not plywood.)

@tsbrownie 2 ай бұрын

Thank you. I've got something in mind for it; still waiting on parts. We shall see. Yes, the 3D printer covers up my lack of woodworking skills. It's not beautiful (but there is wood filament that has real wood in it and shows changes in color like wood. Hmmmmmm.) Most people who want to do this can probably see what I've done and recreate it in wood. I like the steam-punk idea. Of course crystal radios are already kind of steam-punky as-is. Actually I could change the 3D printed shapes into plumbing-looking stuff and print it in copper color! OK, we went through that already.

@franzliszt3195 2 ай бұрын

I'm not convinced air core is better, yet. A lot of flux is lost between the air core windings that are otherwise captured by the ferrite core.

@adnacraigo6590 2 ай бұрын

I am thinking that you may be correct about the ferrite consuming some of the signal. I think of it as if the coil were wrapped around a metal cylinder of sorts.

@tsbrownie 2 ай бұрын

I agree. The people who do crystal radio contesting use air core coils.

@franzliszt3195 2 ай бұрын

I had though air core was used because it was required by contest rules?@@tsbrownie

@y_x2 2 ай бұрын

You should measure the Q factor.

@vintagetransistorRadio.Radio.h 2 ай бұрын

Vooo thanks for sharing ❤️ 👍 🙏 😊 ❤❤❤❤❤❤❤❤❤❤❤

@tsbrownie Ай бұрын

Thanks for watching

@franzliszt3195 2 ай бұрын

Well, I wonder about your ferrite core. What is the highest frequency station you get on it?

@tsbrownie 2 ай бұрын

1600 kHz. I tested it with a frequency generator and scope and it looks pretty efficient.

@franzliszt3195 2 ай бұрын

If I recall, in a vid you said the relative permeability was 1000. I would think it would have blown the air inductor out of the water. Strange. Is the diode reversed? The diode white bands look orientated differently on the two recievers.@@tsbrownie

@tsbrownie 2 ай бұрын

@franzliszt3195 The relative permeability varies from 10s to thousands, so unless you order from a mfg or qualified distributor, you rarely get that number. I don't recall the formula for it and how it's related to Q. I'm sure there must be different qualities of the stuff as well. Too many variables and not enough rock solid info.

@hobbyrob313 2 ай бұрын

HOOWWWWwww just this: be careful not to place the two coils too close together!!!!!! it may be that one is disrupting/pulling away the signal from the other. (like a kind of dipmeter!) And have you also tried replacing the diode alone? . well, don't put it aside, that's such a shame! I'm glad you're trying to figure out what's wrong. (I'm curious now too! What makes the RX insensitive?) Healthy and Friendly Greetings from here! Rob.

@tsbrownie 2 ай бұрын

Thank you. I used to go on business when I was younger and single. Now I'm married with children. ;)

@hobbyrob313 2 ай бұрын

Hello again! I would say divorce and go back to the Netherlands again! ;-) LOL Healthy and Friendly Greetings again! Rob

@tsbrownie 2 ай бұрын

@@hobbyrob313 I'll have to ask my wife if that's OK. ;)

@tenlittleindians 2 ай бұрын

It does kind of make sense that your air core kicks out more volume. The only energy is coming through the air into the wire. The radio with more wire has more power. Those old radios in the 20's ran long 100 foot or so wires out of windows to high up in tree trunks or the side of barns to maximize input power. Now you got me wondering if those early crystal sets wound on Quaker Oats cereal containers were even better because they had even bigger windings to absorb radio energy? There were a lot of failures trying to build those old published Quaker Oats radio designs and that's because modern cereal boxes are now smaller in diameter which threw off all the winding calculations. Someone figured that out and got a modern sized box to work by adjusting the windings but I don't remember anyone doing a comparison between a full sized box and a modern smaller sized box. Unfortunately only the collectors with full sized boxes have the radios to test with.