daemon@rutgers.UUCP (03/04/87)
From: prindle@NADC I recently realized that some sites may have received this schematic with a few important lines deleted by the mailer - thus I am re-posting it with line numbers - if lines aren't consecutively numbered, there are again lines missing (hope not). Cheers, Frank Prindle --------------------------------schematic begins-------------------------------- 00 Commodore 128 RGBI to Monochrome (Gray Scale) Adapter 01 ----------------------------------------------------- 02 03 RGBI(DB9) 04 Connector 05 --------- (User Port Pin 2) 06 * 100 DIODE +5 Volts 07 Pin 3 R>---/\/\/\/--->|----+ v 08 | 680 | 09 * 220 DIODE | +--/\/\/\/--+ 10 Pin 4 G>---/\/\/\/--->|----+ | | 11 | | 2N2222 | 12 * 300 DIODE | 100 100 | |-----+ 13 Pin 5 B>---/\/\/\/--->|----+----/\/\/\/--+--/\/\/\/--+-----| 14 | | |->---+--------> 15 * 240 47 | | | Video 16 Pin 6 I>---/\/\/\/---------+----/\/\/\/--+ | +-----+ Out 17 | | | To 18 | 33 | | 82 Monitor 19 +----/\/\/\/--+ | +--/\/\/\/--+--> 20 | | | 21 V | V 22 (gnd) | (gnd) 23 2N2222 | 24 100 |-------------------------+ 25 Pin 8 H>---/\/\/\/---------| | 26 |->---+ | 27 | | Note: + denotes a 28 V | connection; there 29 (gnd) | are no crossovers 30 2N2222 | in this schematic. 31 100 |-------------------------+ 32 Pin 9 V>---/\/\/\/---------| 33 |->---+ 34 | 35 V 36 (gnd) 37 38 Pin 1 >------------------------------+ Note: Carry both grounds through 39 | and tie both to ground to avoid 40 Pin 2 >------------------------------+ signal degradation. 41 | 42 V 43 (gnd) 44 45 * These four resistors determine the gray scale. As specified, they provide 46 16 different gray levels, some of which are only barely different - red is 47 most heavily weighted, green next, and blue is lightly weighted. To allow 48 experimentation or customization of gray scale, mount these resistors on 49 a DIP socket or use 500 ohm trim-pots. 50 01 > Drawing schematics with ASCII characters is an imprecise art. If you don't 02 see three (3) transistors above, keep looking; they are there! I believe 03 the diodes I used were germanium - if you use silicon, the picture may be 04 dimmer overall unless you adjust the weighting resistor values.