MultiDisplay Technical Files

Additional technical information for the MultiDisplay board is provided on this page. If you intend to get a kit or a bare board, examine this material carefully, because thatís all there is... I will not provided step-by-step instructions on how to assemble it... If you canít figure out how it goes together, ( based on the information available here ) you should get a board that is already assembled and tested. Obviously, reasonable "soldering skills" are also required. It takes about 2 hours to assemble and test a bare board.

I have not offered a kit before, so this will be an interesting experience. I guess I should offer to repair any boards, for a flat labor rate of US$ 40, plus any parts required. ( return shipping not included, add $10 ) It really shouldn't be too hard for anyone but a complete ( homebrew ) novice... and it's a lot of fun to build something and see it work.

The Download Files

Here are downloads for the technical files of the MultiDisplay board :

[Schematic Diagram] ( sheet 1 of 2, pelorus circuits and RS232 )
[Schematic Diagram] ( sheet 2 of 2, numeric circuits )
[Parts List]
[Non - CAD Artwork] ( component side )
[Non - CAD Artwork] ( solder side )
[Non - CAD Artwork] ( silkscreen )

( NOTE : the boards donít have a silkscreen printed on them... use the silkscreen diagram to locate and install the parts on the board... it is derived from the CAD file )

[Artwork detail] ( external connections and option straps )

[PIC assembly Source code] for the 16C773
[PIC assembly Source code] for the 16F84


Assembly Notes

The voltage regulator MUST be mounted on the BACKSIDE of the board, which explains why it is absent from the photograph on the previous page... this was done because the board normally will be mounted directly next to a display panel, which leaves no room ( on the frontside of the board ) for a heatsink, if one should be required.

As it turns out, the regulator seem to run just fine without a heat sink ( at room temperature, from a 12 volt source ) but I wasnít sure of that when I designed the board. There is a small amount of heat sink "area" provided on the board itself, and it seems to be adequate.

As for the pelorus LEDs, orient them so that the cathodes face the INNER part of the pelorus circle, and the anodes face the OUTER part of the circle.

INFO : The Pelorus LEDs and numeric readouts are available in different colors, if you desire that... Check the parts list, which contains DigiKey part numbers... You can visit the DigiKey website and do a "search" for those part numbers... that will lead you to the catalogue page for the parts, where you will find similar LEDs with alternative colors. ( applies if you buy a bare board )

To ensure equal height for the numeric and pelorus LEDs, it is best to install the numeric readouts first, then install ( but do not solder ) all the pelorus LEDs. Turn the board over so that it rests ( upside down ) on the surface of the numeric LEDs, and push the ( loose ) pelorus LEDs all the way down until they contact the table surface. ( equal height above the PC board ) THEN solder them. Otherwise, the pelorus LEDs will be "recessed" from the panel, because the numeric readouts are much "taller" than the pelorus LEDs.

The cylinder crystals for the microcomputers are housed in nickel-plated enclosures, and can be soldered down onto the PC board, to anchor them against vibration. A small area is provided for this, next to each crystal.

This may be dumb, but I better say it... the side of the board with the 6 circular tracks is the component side... donít install everything and then discover you have confused the two sides... I forgot to label them in the artwork.

Pin 1 on each IC ( and the numeric LEDs ) is identified with a square pad, instead of a round pad. For additional orientation on the numeric readout LEDs, look for the decimal point and compare it to the photo on the previous page. For the transistors, be sure to observe the orientation shown in the silkscreen diagram. Same for electrolytic caps.