Retro Audio - Space Invaders Sound Effect Circuits

In this video I will be playing around with some old sound circuits from the classic Space Invaders machine.

Here the github repo containing the kicad, ltspice and code
https://github.com/thaaraak/Space-Invaders

Here's my google drive with a pile of the documents I referred to (the TI Applications document is in here)
https://drive.google.com/drive/folders/1wN9LfC7sWyIfdF__VMJKV20dDnsGLjPI?usp=sharing

Here's Joe's original video
https://www.youtube.com/watch?v=ppvjhf4vhdQ&

The article on using shift registers to generate a pseudorandom bit stream
https://www.eetimes.com/tutorial-linear-feedback-shift-registers-lfsrs-part-1/

Where I sourced the parts from (no affiliation)
CD4006 https://www.aliexpress.us/item/3256803998192800.html
CD4070 https://www.ebay.com/itm/401389436743
LM3900 https://www.ebay.com/itm/203486171172?var=503839183781
556 https://www.ebay.com/itm/293751852498

0:00 Intro
0:24 The schematics for the Taito game
1:30 Quick note on the LM3900 Norton OpAmp
4:14 Invader Stepping sound circuit
7:05 Stepping sound on the breadboard
8:09 Stepping sound audio
9:00 Step sound on the oscilloscope
9:45 Noise generator schematic walkthrough (sorry about the background hum)
11:57 Noise generator on the oscilloscope
13:58 Noise sent to the audio output
14:57 Player killed schematic walkthrough
15:49 Setting the sustain time impulse
17:39 Attack and decay circuit
18:30 Attack and decay on the oscilloscope
21:31 Combining the envelope with noise
22:25 Explosion sound on the oscilloscope and wrap up