You can get mondo 7-Segment displays from various places. The biggest ones I've seen are 4" tall, and are about $40 US (http://rocky.digikey.com/WebLib/Lite-on/Web%20Data/LTS-50801HRB.pdf from digikey). The segments are made up of lots of individual series LEDs, and thus require higher voltages than usual to operate. The 74LS47 or 74LS48 is a chip that can drive a 7 segment display, given BCD inputs. I don't think it can drive these big ones, though; they take 60mA continuous, and the '47 can only drive about 20mA. Thus, you need a driver chip like one of those ULN2003A chips. Use a 74LS48, into the inputs of a ULN2003A though a 1k 7 resistor array. The outputs of the ULN2003A go to the common cathodes of the display unit though another 7 resistor array. The value of this array depends on the input voltage in your clock. Arrange it so that the display is passing around 60mA when its on. The inputs to the 74LS48 can either be driven directly from a PIC, or driven by a shift register. That way, your display information can be encoded using a 3 wire data/clock/strobe interface. You can even cascade the whole thing, so that one 3 wire input controls all the digits. Thats the simplest way. You can even control this directly using a parallel port driver from a PC. Regards, Bob Monsen ----- Original Message ----- From: "Martin McCormick" To: "Microchip PIC microcontroller discussion list." Sent: Saturday, August 28, 2004 7:03 AM Subject: [EE]: Display possibilities > I want to have a lighted display in a clock in which the > digits are in the general range of 2 to 4 inches high. If someone > makes individual digits like that then I will need to build a > controller for them, of course. > > If there is a display module that fits this general > description, then I need to be able to connect it using DIP headers or > something similar that I can accommodate with wire wrap technology. > > The idea is to make the clock work first and add the display > last such that the clock treats the display like a peripheral and > updates it but doesn't concern itself with lighting up this or that > segment. It would just send out BCD or ASCII digits to a second PIC > that managed the display itself. > > What I don't desire is what I have seen in some devices I have > salvaged in which there is a ribbon of 4 score and 7 tiny stranded > conductors wave soldered to the surface of both the display board and > the main board. That is not my idea of fun. I am sure it works fine > in a mass-production environment, but not here.:-) > > Thanks for any useful ideas. This is a one-of-a-kind project, > but one never knows where these things can lead. > > Martin McCormick WB5AGZ Stillwater, OK > OSU Information Technology Division Network Operations Group > _______________________________________________ > http://www.piclist.com > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > _______________________________________________ http://www.piclist.com View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist