Good article. I would add however that passive pull-up or -down resistors make for very slow transitions since the capacitance to charge up on the line is not 0. For example, with a 10K pull-up resistor and 20pF of capacitance on the line, the pull-up time constant is 200ns, which is very, very slow by digital standards. In some of the circuits, a compensating capacitor can be added; for example, in figures 1 & 2, put a 10pF across R1 [Edit:
Correction: see my next post below]; in figure 3, you could put it put it across the diode if the trr of the diode isn't already long enough or its capacitance enough; and in figures 4, 7, and 8, putting it across R1 will help turn the transistor off and on faster but will not help raise the collector voltage any faster when the transistor turns off.
I show using an LM339 (quad) or LM393 (dual) comparator for voltage translation at http://wilsonminesco.com/6502primer/pot ... HI_V_LOGIC
, but this is not for very high-speed logic. I've used it primarily for 5V-to-12V logic, like 5V to 4000-series which isn't very fast anyway but can go up to 15V. I've used the 4000-series stuff primarily for analog switches, the 4066, 4051, 4052, and 4053, for controlling audio circuits that use a 12V power supply.