On 2012-05-13, at 22:16, Gerrit Heitsch wrote: > > Sure... I think I posted it before, but a bit of ASCII-graphics won't hurt: > > Video amp for TED or VIC-II. To be used in place of the RF > modulator, generating better signal quality. > > Note: This circuit removes the CVBS output! It's Y/C only! > > ___ R1 > chroma in -----|___|---+ +5V > | | > | | > R2 | | > ___ | |/ > +----|___|---*----| T1 > | |\ > | R4 R3 V > | ___ ___ | > *--|___|--*--|___|--+ > | | > | | || C1 > --- +--------||---------- chroma out > GND || > > > D1 R5 +5V > ___ | > luma in ---|<|--*--|___|--*-------------------+ > | | | > | | | > | |/ === C2 > +-------| T2 | > |\ | > V | > | R6 R7 | > | ___ ___ | > +--|___|--*--|___|--* > | | > | --- > | GND > | > +--------- luma out > > > T1 = T2 = BC547B > D1 = 1N4148 > R1 = R2 = 510 Ohm > R3 = 68 Ohm > R4 = 270 Ohm > R5 = 470 Ohm (TED manual suggests 1 KOhm) > R6 = R7 = 150 Ohm > C1 = 1nF > C2 = 100nF > > Do _not_ use metal film resistors, keep connections short. I laid out something like here: https://dl.dropbox.com/u/58002657/C64_rf_modulator_replacement.png trying to keep the signal paths (traces) short. It is not yet meant to be placed in the metal housing of the modulator but if that works well I may take some efforts to make a replacement board that goes inside the metal case. The "upper" part is an audio amp for the SIDs. Any comments / striking errors in this? What should I put more attention to? -- SD! Message was sent through the cbm-hackers mailing listReceived on 2012-07-08 13:00:09
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