In this episode, I rant about teardowns, products vs projects, LCSC, and the ESP32 microcontroller.
It was a strange week. I have my first “real” job since 2003. (I’m talking full-time job.) It was a struggle to get this podcast out. I’m feeling my grip on my my reality from just 5 days ago slip away. Regardless, I was able to maintain my usual, low standards. I had plenty to talk about. I spent about a day finding a switch on LCSC. I learned a ton about the JLCPCB Assembly process, and it turns out that school may have been onto something in Python.
Pocast 007 : Incredible Synth Filter, SMD MIDI Optcouplers, and Woes of Production
Last week’s video:
LTspice Potentiometer Download and Install
—– Scowering the web
——- found interesting schematic
——- built it up. It acted weird.
——- I simulated it in LT Spice
——–I It was still weird. It wasn’t a LPF at all, but some kind of goofy resonant peak thing.
——–Later on, I re-read the description and it said, “Fake LPF”. Sigh.
— No forum schematics? Fake news?
— Incredible video on synth design
——-DIY Synth Design Tutorial Series – 003: Analog Filter and Power Supply
———- This guy knows his stuff. He gets into the real design. the.room.dis.connect
—— Introduces LM13700 transconductance amplifier
———- We all know what an RC filter is?
————– The R is little more than current control.
————– The cap is a bucket and the “current” is the flow of water to fill up that bucket.
————— What if we wanted to control R on the fly?….potentiometer
—————— What if we wanted to control a stereo 4-pole filter. We’d need an 8-gang potentiometer.
———- This led the search for a VCR (voltage controlled resistor)
—————I knew a MOSFET’s Rds does this, at least to a certain degree.
—————This would require some real chops
———- Enter the LM13700 transconductance amplifier.
—————— Essentially a VCR… voltage in controls current out.
Filter conclusion: Transconductance amplifiers allow us to control filter frequency.
———— allows creative options as CV
Back to LM13700
— About $1 in quantity
— Plenty of them on Digikey and LCSC
— A mono, four pole filter needs 2.
—- The datasheets “Application Information” is sensational.
SMD Optocoupler For MIDI TLP2361
This guy made a super helpful blog post showing how he made his Teensy MIDI board using TLP2361 opto coupler
This episode had no big theme, but many small ones.
— I’m redoing this podcast because of noise and why that is GREAT!
— I finally hooked a MIDI controller to Reagan Revenge.
— Last week’s Youtube video was Can You Reflow Solder In The Kitchen? https://youtu.be/ioDRD-fo0PY
— Fear of selecting wrong platform (comment on Embedded.FM)
— A programmer without a power source
— Going back to Python
— Talk about e-gas
— Knipex Tools lead catcher plies to keep you from shooting your eye out
— Finish the code before you start the “real” hardware
Does the Arduino programming language have any place in professional products? This is a topic that comes up frequently for people that have a cool idea and feel the pull of product design but feel like maybe they are wimping out if they were to choose Arduino over Embedded C. Embedded C certainly has performance benefits, but that comes with costs of its own….TIME! In this podcast, I rant and rave incoherently about when Arduino programming should be used and should not be used when developing a product. I also talk about wool socks, heating pads, and dinosaur eggs.