Wikipedia:Reference desk/Archives/Miscellaneous/2022 July 10

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July 10

European Cup Trophy

Good evening, I wrote a few years ago about the same subject I am bringing to your attention now. If you look at the picture, you see Matt Busby at the time United manager, lifting the miniature replica of the European Cup after the victorious final against Benfica in '68. Is it possible according to my reconstructions, because I have viewed other videos, that the miniature cup could have gone to either the manager, the chairman or a representative player such as the captain I know? I say this because when Ajax won the European Cup for the first time in '71, the miniature cup was presented to the club's chairman who lifted it as a sign of victory. Let me know, whenever you want and if you want I am here. Thank you very much.

https://www.google.it/search?q=matt+busby+european+cup&sxsrf=ALiCzsbAJvRkBjhLwLr0WGRjZ6hCHAuLyw:1657477012686&source=lnms&tbm=isch&sa=X&ved=2ahUKEwif0MGE9-74AhXHnf0HHcGnCnUQ_AUoAXoECAEQAw&biw=1964&bih=985&dpr=0.9#imgrc=gJdNVRfvPNzn8M 93.41.96.190 (talk) 18:18, 10 July 2022 (UTC)

I couldn't find anything specific, but I imagine that the miniature ended up in Man United's Trophy Room. The actual cup had to be handed-back before the next tournament, unless the club had achieved five wins or three consecutive wins. [1] If you don't get a better answer here, it might be a good idea to ask the club directly, or find a dedicated fan forum (like this or this or this). Alansplodge (talk) 14:06, 12 July 2022 (UTC)

Squarewave Oscillator for Casette Recorder

An analog audio cassette recorder contains a high-frequency oscillator that A) drives the erase head to restore the magnetic tape to unrecorded state and B) superimposes a supersonic AC bias on the input to the recording head; this counteracts the nonlinear coercivity of the magnetic tape coating to improve the signal-to-noise ratio and frequency range. The amplitude of the AC bias is known to be critical but the oscillator circuits in use seem to be simply designed i.e. to give a nominally sinewave output but without an expressed distortion target. Presumably the inductance of the erase and recording heads will attenuate any higher harmonics of the bias frequency. I want to repair a Grundig cassette recorder whose oscillator circuit has a defective transformer that is sadly unobtainable. Is adding a square-wave oscillator like this[2] going to work? Philvoids (talk) 21:14, 10 July 2022 (UTC)

While I have no expertise in the matter, I saw this statement: "It is important that the AC bias signal must be a pure sine wave."^[3] Other sources also stress the use of a pure sine waveform.^[4][5][6]  --Lambiam 21:44, 10 July 2022 (UTC)

Thank you for all those references. I am looking for clarification of the distortion target "must be a pure sinewave". I see why the bias oscillation must be high in frequency, must be unmodulated and must be free of DC bias. However I cannot see why odd-order harmonic content would reduce its performance. This motivates my interest in the simplification of using a square wave voltage that contains only components of odd-integer harmonic frequencies. (The currents in the erase and recording heads will not be squarewaves.) Philvoids (talk) 18:12, 11 July 2022 (UTC)