{"id":454,"date":"2017-09-05T02:40:00","date_gmt":"2017-09-05T02:40:00","guid":{"rendered":"http:\/\/tubetime.us\/?p=454"},"modified":"2017-09-05T02:40:00","modified_gmt":"2017-09-05T02:40:00","slug":"simple-commodore-pet-tape-interface","status":"publish","type":"post","link":"https:\/\/tubetime.us\/index.php\/2017\/09\/05\/simple-commodore-pet-tape-interface\/","title":{"rendered":"Simple Commodore PET Tape Interface"},"content":{"rendered":"<p>Before I put together a <a href=\"http:\/\/petsd.net\/\" target=\"_blank\">long term solution<\/a>, I wanted a quick way to transfer software from my PC to my Commodore PET. There are other circuits, but I wanted something that used just one part. <\/p>\n<p>The PET input is TTL level, so I needed something to go from audio level to TTL. Ideally a comparator circuit with plenty of gain. Well, I couldn&#8217;t find a decent comparator in my junk box, but I did find a CA3140 op-amp. This is way faster than I needed, but should work OK as a comparator. If you build this circuit, try to find a comparator or an op-amp with a rail-to-rail output.<\/p>\n<p>Here is the circuit:<br \/>\n<a href=\"http:\/\/tubetime.us\/wp-content\/uploads\/2017\/09\/PetAudioSchematic.png\"><img loading=\"lazy\" src=\"http:\/\/tubetime.us\/wp-content\/uploads\/2017\/09\/PetAudioSchematic.png\" alt=\"\" width=\"400\" height=\"187\" class=\"alignnone size-full wp-image-455\" \/><\/a><\/p>\n<p>And here&#8217;s what it looks like:<br \/>\n<a href=\"http:\/\/tubetime.us\/wp-content\/uploads\/2017\/09\/PetTape.jpg\"><img loading=\"lazy\" src=\"http:\/\/tubetime.us\/wp-content\/uploads\/2017\/09\/PetTape.jpg\" alt=\"\" width=\"400\" height=\"300\" class=\"alignnone size-full wp-image-456\" \/><\/a><\/p>\n<p>It works quite well. The circuit is not very sensitive to the output audio level from the PC&#8211;I set mine halfway (line level) and it was fine.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Before I put together a long term solution, I wanted a quick way to transfer software from my PC to my Commodore PET. There are other circuits, but I wanted something that used just one part. The PET input is TTL level, so I needed something to go from audio level to TTL. Ideally a [&hellip;]<\/p>\n","protected":false},"author":4,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"jetpack_publicize_message":"","jetpack_is_tweetstorm":false,"jetpack_publicize_feature_enabled":true},"categories":[5],"tags":[],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p80Z1r-7k","_links":{"self":[{"href":"https:\/\/tubetime.us\/index.php\/wp-json\/wp\/v2\/posts\/454"}],"collection":[{"href":"https:\/\/tubetime.us\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/tubetime.us\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/tubetime.us\/index.php\/wp-json\/wp\/v2\/users\/4"}],"replies":[{"embeddable":true,"href":"https:\/\/tubetime.us\/index.php\/wp-json\/wp\/v2\/comments?post=454"}],"version-history":[{"count":2,"href":"https:\/\/tubetime.us\/index.php\/wp-json\/wp\/v2\/posts\/454\/revisions"}],"predecessor-version":[{"id":458,"href":"https:\/\/tubetime.us\/index.php\/wp-json\/wp\/v2\/posts\/454\/revisions\/458"}],"wp:attachment":[{"href":"https:\/\/tubetime.us\/index.php\/wp-json\/wp\/v2\/media?parent=454"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/tubetime.us\/index.php\/wp-json\/wp\/v2\/categories?post=454"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/tubetime.us\/index.php\/wp-json\/wp\/v2\/tags?post=454"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}