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Article #2023Re: Simple crystal (4.43MHz - PAL) oscillator + PLL multiplier circuit wanted.
From: Tam/WB2TT
Date: Mon, 05 Mar 2007 14:13
Date: Mon, 05 Mar 2007 14:13
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2266 bytes
"Lionel" <usenet@imagenoir.com> wrote in message news:ksknu25mu0q4p10p0qhi0u56uihln1ndde@4ax.com... .....................................that a good starting place might be to use a CPU clock > that's based on the PAL subcarrier frequency (4.43MHz) multiplied with > a PLL+VCO+Divider to give me phase reference points, & directly > generate the composite colour signal via an R2R ladder. > You might want to consider the converese of that. 20+ years ago it was common in cheap computers here to start with an oscillator at 14.318 MHz, which was then counted down to the NTSC color subcarrier frequency of 3.579 MHz. 14.318 is also an integral multiple of the horizontal and vertical sync frequencies. I see that 17.734475 is a standard crystal frequency. Is that 4x the actual PAL frequency? Tam
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