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 ... https://www.youtube.com/watch?v=haHSgdZHHwc

I have been looking for an alternative to the awesome Iowa hills filter software for some time. I came across this video https://www.youtube.com/watch?v=b5DevnKMpDo Which explains in steps how to create a Hilbert filter and associated delay line using Matlab. Charlie's original video: https://www.youtube.com/watch?v=M4OKr2Zpcj0&t=579s I adopted this approach in python using the scipy.signal library here: https://github.com/thaaraak/ESP32-Arduino-Audio/blob/main/hilbert_generator.py This video is a quick walkthrough of that code and a demonstrate on the filter taps using my previous ESP32 based audio processing here: https://github.com/thaaraak/ESP32-IQ 0:00 Intro and why I am looking for an alternative to Iowa Hills 0:53 The Hilbert Filter + Delay Line approach 2:00 Python Hilbert generator Code walkthrough 4:22 Creating a sample filter 5:05 Looking at the frequency response of the filter 5:35 Convolving a sample sine wave through the Hilbert and Delay line 7:21 Using the coefficients created in an ESP32 based audio processor 8:19 Looking at the output on the oscilloscope ... https://www.youtube.com/watch?v=BUGQaTJ6aWI