2022-06-19 01:32:24 Yes, it's just an LC tank. It "Q boosts up" the frequency range it's tuned to, and then the radio can pluck those boosted fields from the air or take some energy coupled from the big loop into its antenna input. 2022-06-19 01:32:32 It's a very simple idea, actually. 2022-06-19 01:33:15 And yes - I've already been thinking of experimental things I can tack onto it later. 2022-06-19 01:33:39 Shouldn't be too hard to turn it into a simple direct conversion receiver. 2022-06-19 01:33:50 With the tuning done in the antenna loop. 2022-06-19 01:34:43 Stuff like that is really just good for hobby stuff only these days, though - software defined radio really has totally changed the "real" technology. 2022-06-19 01:35:51 For AM broadcast the frequency is so low I even thought about the possibility of building my own digitizing circuitry from transistors and doing an AM only software radio. 2022-06-19 01:36:16 So there's two things already I might play with "appending" to this loop. 2022-06-19 01:37:30 I can't help wondering if it could be as simple as putting a "dumpable" rf peak detector in the right spot and then digitize that at audio frequency, with a charge dump in between each sample. 2022-06-19 01:37:51 Or maybe even just a low-pass filter, and let it filter the modulation frequency range out of the RF. 2022-06-19 01:38:18 Either amplify that and play it through a speaker, or digitize it with a cound card. 2022-06-19 01:38:20 sound 2022-06-19 01:46:55 I suspect the technology is adequate these days to put an entire "low bands comm receiver" on a single chip, but the industry seems much more focused on the higher frequencies used in cell phones and other popular consumer gadgets. 2022-06-19 01:46:59 Guess that's not surprising. 2022-06-19 01:47:46 I'm also finding that there's one HELL of a lot more noise on the AM broadcast and SWL/ham bands than there was several decades ago when I was previously interested in this stuff. 2022-06-19 01:48:02 All these gadgets we have that didn't exist back then are big "noise polluters." 2022-06-19 01:48:39 This antenna I'm building is highly directional, so in some particular cases I might be able to rotate it to null out some particular bit of noise. 2022-06-19 01:49:21 But other than that possibility, improving the antenna doesn't do diddly to help beat externally generated noise - it just gets boosted right along with the desirable signals if it's in that frequency range. 2022-06-19 01:50:05 I've got an exhaust fan that pulls air from my garage into my attic - I put that in some years back when I was mining bitcoin out there. 2022-06-19 01:50:15 That thing I have to turn off when I'm trying to use the radios. 2022-06-19 01:50:26 It makes a hell of a racket all over the bands. 2022-06-19 01:51:05 And nothing will ever get done about it - ultimately no one really cares about the low frequency stuff any more. 2022-06-19 01:51:32 A big portion of the shortwave broadcasting stations, at least in the State, seem to have been sold off to evangelical organizations. 2022-06-19 01:52:10 Back in the 1970's 1980's all the major governments of the world mounted major shortwave broadcast efforts. I think a lot of that energy has been shifted to using the internet to put out their propaganda. 2022-06-19 01:53:02 Back the the Voice of America, for example, was probably the ony way the US government could directly deliver information to most people in the world. But these days information is everywhere, from everyone, right in our pockets. 2022-06-19 01:53:29 Like so many of my "interests," I'm into it primarily because I just admire the technology and want to understand it. 2022-06-19 01:56:08 I remember once back then (80's) I stumbled across a "numbers station." An unidentified broadcast, with a person just reading off an endless series of numbers. 2022-06-19 01:56:52 I scratched my head over it, but then a few years ago on the TV s how "The Americans" Elizabeth and Phillip listened to just such a broadcast on a shortwave receiver, and deciphered the numbers with a code book to get their latest instructions from Moscow. 2022-06-19 01:56:57 Made total sense then. :-) 2022-06-19 01:57:54 These days I imagine the same kind of thing goes on with alt.binaries newsgroups. 2022-06-19 01:58:49 But there is a difference - the government can keep up with who accesses alt.binaries, whereas back then you just went to any Radio Shack and picked up a shortwave receiver, and you could hear from your handlers without leaving any trace whatsoever. 2022-06-19 02:00:08 Another fun thing to listen to back then was ship-to-shore phone patches from cruise ships. Just people phoning family and tellng them about how snappy their cruise was so far. 2022-06-19 02:02:20 Zarutian_HTC: Regarding that antenna being "just a tank circuit," just think about what that's going to do. Every wave from the remote station that passes through that loop is going to give it a little nudge, and for the resonant frequencies those nudges build up a "Q times" stronger current in the loop. And now THAT current creates fields inside the loop, that adds to the fields passing through naturally. 2022-06-19 02:03:05 It would be like putting your kid in an unbelievably low-friction swing. If the friction was low enough, you could build him up to a big swing amplitude just by exhaling on him at just the right time each swing. 2022-06-19 02:03:33 Practically, the loop current stops building up when the amount of energy being added each cycle matches the resistive losses for a cycle. 2022-06-19 02:03:49 So if the resistance is low enough, that can wind up being a large oscillation in the loop. 2022-06-19 02:05:08 So long as the thing still responds "in toto" fast enough to mirror audio frequency information, it's like getting to excite your receiver with hundreds of thousands of cycles worth of energy, instead of just one at a time. 2022-06-19 02:08:31 The Q of this loop looks like it's going to be so good that I have to add a deliberate potentiometer to the circuit, to lower the Q enough to get a proper bandwidth. 2022-06-19 02:08:56 And if I set it up so that I have some switches to let me choose how many turns to use, I can have it tunable over the shortwave bands as well. 2022-06-19 21:34:16 http://www.call-with-current-continuation.org/uf/uf.html 2022-06-19 21:55:57 challange: in above linked forth, write a 'snapshot' word that uses the 'save' word and saves the stacks. Up on 'boot' of the saved uxn rom file restore the stacks 2022-06-19 22:50:12 How on earth that they arrive at 2496 byte blocks? Well, it's 39 64 char lines, but... how that? 2022-06-19 22:51:20 Does this run on Linux?