sk540-ramps

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Some calculations

time to charge a capacitor:
t = -ln(1-Uc/Ucharge)*RC

Uc = 1V
Ucharge = 5V

so we have t = 0.22314355 * RC

horizontal ramp: 64uS -> 0.0000064 = 0.22314355 * RC
RC = 0.00028681088753

vertical ramp: 20 ms (1 field) -> 0.02 = 0.22314355 * RC
RC = 0.08962840235449

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Inputs: N/A N/A

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December 7, 2013 @ 15:47:14Current Revision
Content
Some calculations Some calculations
time to charge a capacitor: time to charge a capacitor:
t = -ln(1-Uc/Ucharge)*RC t = -ln(1-Uc/Ucharge)*RC
Uc = 1V Uc = 1V
Ucharge = 5V Ucharge = 5V
so we have t = 0.22314355 * RC so we have t = 0.22314355 * RC
horizontal ramp: 64uS -> 0.0000064 = 0.22314355 * RC  horizontal ramp: 64uS -&gt; 0.0000064 = 0.22314355 * RC
RC = 0.00028681088753 RC = 0.00028681088753
47nF, 6.1 kOhms
vertical ramp: 20 ms (1 field) -> 0.02 = 0.22314355 * RC  vertical ramp: 20 ms (1 field) -&gt; 0.02 = 0.22314355 * RC
RC = 0.08962840235449 RC = 0.08962840235449
10uF , 8.9 kOhms -&gt; 10k pot
does not work: <strong>ATTENTION the 4053 can have up to 2k5 Ohms ON resistance</strong>. we have to discharge the cap in max 9uS - length of h-sync + back porch
0.000009 = 0.22314355 * 2500 *C -&gt; 16nF max
4n7/61k
also: the v-ramp we want to charge only on h-sync, so that's 313 pulses of 10.4 uS, total charge time of 3.255 ms. Discharge in max 0.5ms.
discharge: 0.0005 = 0.22314355 * 2500 *C -&gt; max 890nF
charge: 0.003255 = 0.22314355 * R * 100nF, R = 145.8k

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