Reproduction SCELBI Cassette Write Card

Here’s a link to an original write card for comparisions sake.

Except for the relay, I soldered chips directly on the board. Departing from what I did with my SCELBI RAM boards, where I used NOS solder tail sockets, I used a machine pin socket for the relay. No serious issues were found during the build. I powered up and found it draws about .25 AMPs, so I put in a .5 amp fuse. The BOM I published in a previous blog entry was missing a 74121, but I had one of those on hand. I used a 2n3904 transistor to drive the relay and the schematic is missing the value for a 1K resistor. There is a place for a capacitor on the output, but none exists in the images of actual boards that I have seen, so I left it out.

I just noticed I forgot to put in the jumper next to chip Z6.

Outside of some articles in Micro-8 newsletter and some mention in other documents, we don’t have any original documentation for SCELBI peripherals. Once I get everything working, I’m going to have to create some docs for these cards.

After adding the jumper, I’ll build a cable between an edge connector and an 86CP11 connector, so I can plug it in to my 8B and see what happens. I will eventually put it and the read card in an a small aluminum enclosure like the originals had.