From: Jim <jim@jpes.com>
To: Microcontroller discussion list - Public. <piclist@mit.edu>
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Date: Wed, 25 Nov 2020 21:14:58 -0800
Subject: RE: [OT] Hyperikon Retrofit LED Tubes Without Ballast and
 fluorescent	lamps and TV!
Thread-Topic: [OT] Hyperikon Retrofit LED Tubes Without Ballast and
 fluorescent	lamps and TV!
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The color burst frequency is 3.579545 Mhz.

Regards,

Jim

> -------- Original Message --------
> Subject: Re: [OT] Hyperikon Retrofit LED Tubes Without Ballast and
> fluorescent lamps and TV!
> From: "Harold Hallikainen" <harold@mai.hallikainen.org>
> Date: Wed, November 25, 2020 5:41 pm
> To: "Microcontroller discussion list - Public." <piclist@mit.edu>
>=20
>=20
> On the TV fluorescent lamps, yes the frequency was much higher than the
> frame rate (though I don't remember what it was).
>=20
> NTSC television is interesting! It's described at
> http://mai.hallikainen.org/org/FCC/FccRules/2021/73/682/ . Prior to color=
,
> the field rate was indeed 60 Hz, the power line frequency, to avoid
> rolling "hum bars." With color, it appears everything is based on a
> precise 5 MHz with the chroma subcarrier being 5 MHz * 68/88. The
> horizontal scan rate is 2/455 * the chroma subcarrier frequency. The fiel=
d
> rate is then 2/525 * the horizontal scan frequency. I think that the
> frequencies were chosen such that dots created by the chroma signal would
> be white on one scan and black on the next, letting the eye cancel them
> out. Similarly, the European PAL system switched the chroma phase 180
> degrees on adjacent lines (since the image is interlaced, perhaps this
> works out to just being a phase switch on each field). Chroma phase error
> resulted in a hue shift, but in opposite directions on adjacent lines. So=
,
> the eye averaged them out to avoid hue shift due to chroma phase drift.
> Clever!
>=20
> On light flicker, movie projectors used to use an incandescent "exciter"
> lamp to light the sound track. Light would pass through the film to a
> photocell. At first, the film density was varied to carry the audio, but
> later the black to white area (width of a white or black stripe on the
> film) was varied to carry the sound. Of course, if the lamp was powered b=
y
> 60 Hz, you'd get 120 Hz hum in the sound. So, the obvious solution would
> be to run the lamp on DC. But, many projectors instead ran the exciter
> lamp on high frequency AC. There was a power oscillator to drive the
> exciter lamp.
>=20
> On the NE-2, one of my earliest project was an NE-2 based relaxation
> oscillator running off a B battery. Choosing component values, I could ge=
t
> a light flasher or get audio out of it.
>=20
> Harold
> http://w6iwi.org
>=20
>=20
>=20
>=20
>=20
> --=20
> FCC Rules Updated Daily at http://www.hallikainen.com
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