{"id":26690687,"url":"https://github.com/danielcuthbert/sn76477-synths","last_synced_at":"2026-02-13T21:12:23.986Z","repository":{"id":90702300,"uuid":"237946162","full_name":"danielcuthbert/SN76477-Synths","owner":"danielcuthbert","description":"Adventures in making a type 76477 Complex Noise Generator synth ","archived":false,"fork":false,"pushed_at":"2020-02-03T12:17:54.000Z","size":1907,"stargazers_count":1,"open_issues_count":0,"forks_count":0,"subscribers_count":1,"default_branch":"master","last_synced_at":"2025-10-05T15:18:35.079Z","etag":null,"topics":[],"latest_commit_sha":null,"homepage":null,"language":"Prolog","has_issues":true,"has_wiki":null,"has_pages":null,"mirror_url":null,"source_name":null,"license":null,"status":null,"scm":"git","pull_requests_enabled":true,"icon_url":"https://github.com/danielcuthbert.png","metadata":{"files":{"readme":"README.md","changelog":null,"contributing":null,"funding":null,"license":null,"code_of_conduct":null,"threat_model":null,"audit":null,"citation":null,"codeowners":null,"security":null,"support":null,"governance":null,"roadmap":null,"authors":null,"dei":null,"publiccode":null,"codemeta":null}},"created_at":"2020-02-03T11:06:27.000Z","updated_at":"2021-12-25T04:31:24.000Z","dependencies_parsed_at":null,"dependency_job_id":"5effaf15-5d7a-4a8d-915f-833aebba1b1c","html_url":"https://github.com/danielcuthbert/SN76477-Synths","commit_stats":null,"previous_names":[],"tags_count":0,"template":false,"template_full_name":null,"purl":"pkg:github/danielcuthbert/SN76477-Synths","repository_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/danielcuthbert%2FSN76477-Synths","tags_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/danielcuthbert%2FSN76477-Synths/tags","releases_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/danielcuthbert%2FSN76477-Synths/releases","manifests_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/danielcuthbert%2FSN76477-Synths/manifests","owner_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners/danielcuthbert","download_url":"https://codeload.github.com/danielcuthbert/SN76477-Synths/tar.gz/refs/heads/master","sbom_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/danielcuthbert%2FSN76477-Synths/sbom","scorecard":null,"host":{"name":"GitHub","url":"https://github.com","kind":"github","repositories_count":286080680,"owners_count":29417739,"icon_url":"https://github.com/github.png","version":null,"created_at":"2022-05-30T11:31:42.601Z","updated_at":"2026-02-13T06:24:03.484Z","status":"ssl_error","status_checked_at":"2026-02-13T06:23:12.830Z","response_time":78,"last_error":"SSL_connect returned=1 errno=0 peeraddr=140.82.121.5:443 state=error: unexpected eof while reading","robots_txt_status":"success","robots_txt_updated_at":"2025-07-24T06:49:26.215Z","robots_txt_url":"https://github.com/robots.txt","online":false,"can_crawl_api":true,"host_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub","repositories_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories","repository_names_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repository_names","owners_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners"}},"keywords":[],"created_at":"2025-03-26T15:34:31.485Z","updated_at":"2026-02-13T21:12:23.982Z","avatar_url":"https://github.com/danielcuthbert.png","language":"Prolog","funding_links":[],"categories":[],"sub_categories":[],"readme":"# The SN76477\n\nIs a complex sound generator in the form of a monolithic chip produced by Texas Instruments in 1978. If you played ***Space Invadors*** or ***Sheriff*** it was this chip that gave you the sound effects. \n\nBeing a kid of that time, and one interested in sounds and music, I felt building up a synthesisor around this chip was a good way to learn electronics. This repo is my own private Idaho and hopefully it's of some use to you. \n\n## Footprint\n\n![Layout](/images/boardlayout.png)\n\nThe chip is a 28-DIP and has the following measurements: \n\n- 1.78 Mm (0.07 In) Pitch\n- 10.16 Mm (0.40 In) Span\n- 25.15 X 8.89 X 5.08 Mm Body\n\nLooking inside the chip via an X-ray is cool\n\n![Layout](/images/xray.png)\n![Layout](/images/xray2.png)\n\nI've created an Eagle library of the above, so you can just import it into your project and use it straight away. \n\n## Breakout Board\n\nTo make this work better with modern bread boards, you need a breakout board in order to connect all the various components up to. \n\n![Layout](/images/breakoutboard.png)\n\nEventually this will be turned into a fully-fledged PCB\n\n## Pin Functions\n\n\n1. Envelope Select (input)\n2. Ground\n1. External Noise Clock (input)\n2. Noise Clock Resistor\n1. Noise Filter Control Resistor\n1. Noise Filter Control Capacitor\n2. Decay Control Resistor\n1. Attack/Decay Timing Capacitor\n1. System Enable\n1. Attack Control Resistor\n1. Amplitude Control Resistor\n1. Feedback Resistor\n1. Audio Output\n1. VCC\n1. Envelope Select\n1. Mixer Select C\n1. Mixer Select A\n1. Mixer Select B\n1. One-Shot Control Resistor\n1. One-Shot Control Capacitor\n1. VCO Select\n1. Super Low Frequency OSC. Control Capacitor\n1. Super Low Frequency OSC. Control Resistor\n1. Pitch Control\n1. VCO Control Resistor\n1. VCO Control Capacitor\n1. External VCO Control\n1. VREG\n\n## How The Magic Happens\n\nThe SN76477 has the ability to create complex signal waveforms by combining a number of outputs. These outputs (low frequency oscillator and voltage-controlled VCO) added to a selected envelope and manipulating the signals attack, decay, sustain and release (ASDR) results in some beautiful noises. 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