Harvesting wires from old telephone cables, re-use them, about cable capacitance & a SW antenna coil
Please read the description/textbox first. Video/VLOG about how you can harvest high quality wires (in terms of isolation properties and copper properties) of (say) old school telephone wire cables (it is showed in the video). Description of a good SW antenna coil: in this description below.
Of course I mean on 0.24 that many of the showed circuits on my table were NOT (!) published because they were unsuccessful or not suitable for a broad public on You Tube, interested in electronics (!). Sorry for what I say there......
Important is that these old school (1970’s-2000’s, 2010’s) telephone cables (still available now, September 2022) that were made to supply the complete household via analog telephones (from the cellar to the attic, hard wired) had very good isolation properties.
This/thus regarding each separate wire inside, opposite to the other or to the (blank) massive copper wire. All wires are/were in the order of 0,2 mm diameter massive copper wire.
Perhaps polystyrene was used as an isolation material, it has good properties. That is my idea, anyway. (Almost sure).
In this VLOG I also “touch” the idea of parasitic capacitance between 2 wires, in the air, or via a medium. Say two wires in a cable with a certain capacitive (and also inductive, of course) resistance opposite to each other, be it plastic or another isolation material.
It shows (I tell) that (say) very sharp waveforms (made to describe O and 1 in a computer circuit, say between 0 V and 5 V, theoretic values) can deteriorate to “sloppy” waveforms, that cannot be detected properly at “the end of the too long wire”.
In old 1980’s computer magazines we can read that a printer, driven by a too long RS232 cable, did not want to work properly, due to the length of the cable, the cable deteriorated the waveform. Thus the “0” and “1” (often in the say 1-5 V range) that had to drive the printer failed.
Often a 2 meter cable worked OK, but a 4-5 meter cable gave problems. All these issues are, in a kind of way, obsolete now (2022), though the physics (electronics physics) will never change.
Good SW antenna coil for 6 MC-17MC (or lower): 22 windings of this isolated "telephone" wire on a well varnished toilet roll (paper/cardboard) of 4 cm diameter, bridged with a 5-150 pF tuning capacitor. Antenna is 2-4 meter copper wire directly to the top of the coil (indoor antenna). Outdoor antenna: long wire free outside, 10 meters, going to the coil via a very small capacitor: 10 PF, preferred a trimmer from 5-20 PF: thus tunable. Standard values: 8-10 windings, toilet roll 4 cm diameter, well varnished, bridged with a 5-150 pF tuning cap, antenna with a 14 pF cap to the top of that coil, top of the coil via a 50-100 pF to the HF amplifier (= front end) be it a FET or bipolar transistor.
From the top of the 22 wdg coil the 8th winding goes to ground with a switch, so in that case a part of the coil is shortcut, thus leaving for the antenna coil: 8 windings or 8 + 14 windings = 22 windings. All on that well varnished paper/cardboard toilet roll, that has a high Q.
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I keep all my YT videos constant actual, so the original video’s with the most recent information are always on YouTube. Search there, and avoid my circuits that are republished, re-arranged, re-edited on other websites, giving not probable re-wiring, etc. Some persons try to find gold via my circuits. I take distance from all these fake claims. I cannot help that these things happen. Upload 12 September 2022.
