RTL Logic

My goal on the Tic Tac Toe machine was to build an exact replica of the Don Lancaster 1971 design. I have 2 of the MC789 inverters so I could build one unit. I could change the design to use a TTL open collector inverter but it would be nice to have the exact circuit board. If I switched to TTL I could make the board or a kit available. (I figure a total market of under 10 units.) The other item of a exact replica is the lamp color filters. The company AMP Hexseal still makes the filters (No.1813-27). I wonder how much they cost? http://www.apmhexseal.com/lampfilters/filters.htm After two years of looking a found exact replacement JFET transistors (TIS58) for my TV Typewriter restorations. The generic replacement JFET worked but it is nice to have the exact part. http://www.swtpc.com/mholley/CT_1024/CT1024_Index.htm I got these parts on eBay for $1.35 plus $2.70 shipping. 13 TIS58 16 TIS97 7 L7805CV 2 L7808CV 4 L78N08 5 78L05A ------------------------------- Michael Holley swtpc6800(a)comcast.net www.swtpc.com -------------------------------