Vintage Electronics Hobby

Authors experiences History Special Interests

My old vintage Electronics Hobby Photos

In the mid 1970’s, during my teen years, my interest in electronics resulted in my building of a totally “home brew” computer.  It was based around the RCA 1802 microprocessor.  I started with a basic circuit diagram as published in “Popular Electronics” magazine, who referred to it as the Cosmac Elf.  I wanted something “fancier” than the open breadboard type of circuit, so I designed mine based loosely around the IMSAI 8080 that I had seen in magazine advertisements.

Cosmac Elf 1802 home made computer, 1975

It featured eight on/off input switches (7-0) to set the binary data input of HEX digits.  Plus a 2 digit HEX display (0-9, A-F).  Also 4 special EF input switches that could be set to control other devices

1K MEMORY BOARD, home made

The circuit board shown here was an evolution of the original 256 Byte design, adding 1024 more bytes (1K).  I used a kit from Radio Shack to etch the copper backed circuit boards, using my own designs, based on the schematic.

My interest in electronics was spawned at the age of 8 years old, when my dad showed me how to build a home brew “Crystal Radio”, using a 50 foot long copper wire as an antenna, a toilet paper roll coil, cat whisker diode, and headphone set from his dad.

Leave a Reply

Your email address will not be published. Required fields are marked *

The maximum upload file size: 128 MB. You can upload: image, audio, video, document, spreadsheet, interactive, text, archive, code, other. Links to YouTube, Facebook, Twitter and other services inserted in the comment text will be automatically embedded. Drop file here