Macrofab Engineering Podcast

MEP EP#244: Comic-Con for Engineers - Chris CarterChris Carter The owner of Mercury Inc. Mercury Inc. is a design consulting firm with expertise in electrical mechanical software and firmware development DFM for PCB Assemblies Industrial Design What is this? Special Assembly Unique processes Sequences and events Design for Serviceability Documentation Change logs

MEP EP#243: Schematics and Connectors, Name a More Iconic Duo...Parker Battery Charger debacle update Two batteries recovered, One failed Amazon Sidewalk draws electronics from among TI, Silicon Labs and Semtech Amazon Sidewalk, a new shared wireless network for IoT consumer device DXF to Board outlines? Eagles DXF importer doesn’t work all too well Suggestions? AutoDesk Fusion seems to import just fine Stephen Connectors on schematics Rfdave on slack channel asked a question about this Am I the only person who hates a schematic consisting of 1 connector, 2 IC’s, 4 bypass caps with all of the interconnects being done with net names, and no interconnecting wires? Currently working on a design that has multiple boards with cable interconnects How do you like to show this? Reference Designator? Potentiometer board - one board to rule them all Using slots to make panel mount “solder lug” potentiometers into pcb mount Not a lot of values in each taper is available in a t

MEP EP#242: The Heartbeat of Cats and LEDsParker Battery charger and maintainer died Took all my batteries with it Company is replacing the unit Nothing looks particularly wrong with the PCB Assembly besides it being gross SF1565SG Current Mode PWM Controller FQPF12N60C Fet used in the PWM Controller HT46R004 HolTek MCU Cost Effective? Cat Feeder Unreminder Ordered a breakout board for the AEM10941 Super Caps SCCS30B106PRB 10F @ 2.7VDC Solar Panel AM-1816CA 84µA at peak power This is specced at 200lx Will this be enough? LTC2956 draws 0.8μA LEDs at 40μA a piece Total draw when Cat Feed Indicator is on is 40.8μA 5F x (4.5V-3.6V) / 0.0000608 = 74,013 seconds -> 20 and a half hours! Stephen Magnetics Transformers arrived! Be specific with what you ask for and ask questions. I almost got bit with dimensional issues Diy Tag connect Made a pogo pin test connector Mill-Max 0955-0-15-20-71-14-11-0 Pogo pins with solder cup on back Using FR4

MEP EP#241: Failing to Electrocute the ChickenParker Bit of feedback on a live stream People suggesting YouTube live Will set this up for episode 242 The little things no one sees that make projects take forever 3D printer update completed New fans TI calls for lower-cost sensors to boost robot adoption “We don’t see as many robots as we’d like” Elon Musk’s Neuralink implant Pig example Stephen High voltage low current measurement - The circuit evolves Adding resistance measurements The new process Use the resistor measurement probes to measure the screen resistors values and record those Use the resistor measurement probes to measure the cathode resistors and record Plug test harness into the DUT Begin test Program will read voltages and using the resistance measurements it will give you a target voltage. Turn trim pot to set idle current such that the power dissipation is met The load is dynamic and this is an unregulated power supply Looking for bananas Wa

MEP EP#240: Disturbed Solder AccuracyParker Got a fully automatic screen printer! ESE US-2000X Potentially lower our minimal paste size Twitch Live Stream podcasts? Amazon multimeter probes Stephen High voltage low current measurement Don't want to break the connection so a traditional ammeter isn't going to work Sticking with the read both sides of a resistor method Caddock 1776-C681 high voltage high resistance high tolerance divider 1/100 so 0 to 500v becomes 0 to 5v ADC - MCP3551-E/SN 22 bit SPI 2.4 meg ohm input impedance Ideally the voltage divider has a “gain” of 0.01 but if the ADC is directly attached to the divider the gain is around 0.0096 Full scale would be 4.8V instead of 5V Solution: add a buffer AD8244BRMZ Quad buffer Typical offset voltage of 100uV Gain error of 0.03% max on +/-15v rails 10T ohm and 4pf input resistance/capacitance - 10^12 Gain error is now 0.009999999901 - Close enough

MEP EP#239: Frictionless Spherical Cow TransformersParker Garage Door opener hacking Converting my normal style garage door opener to a “jackshaft” style opener Reversing the direction of the A/C single phase motor? Split phase motors One phase is shifted with a large capacitor by ~90 degrees In my application I just had to reverse the wires and the end stop wires PyInstaller Can take your python scripts and make it into a self contained application Useful for non technical inclined people on your team Cross Platform! GUIs Tkinter seems to work well in Win10 and Ubuntu 20 LTS Stephen High voltage low current measurement Tony_W Recommended the ACS37002 Hall effect sensor that can be ground referenced in very high voltage applications 0.85m ohm conductor resistance 4.8kV RMS isolation voltage VCC of up to 6.5V -50 to 50A sensing range Gain selection of 30mv/A to 60mV/A In my situation I would want to monitor 0.1mA or 100uA. With a gain of 60mV/A that would be 60u

MEP EP#238: Better Encryption than Zoom, Firmware Stacks with AND!XORAND!XOR Previous podcast episodes: Incognito Mode which was episode number 69 Arduino, The Gateway Drug To #BadgeLife which was episode number 109 Espress-ify? Designing Products Around the ESP-32 Platform which was episode number 144 Feel the Hum which was episode number 183 Firmware RTOS vs No OS (i.e. Arduino or pure SDK usage) What about a Bootloader? Zephyr RTOS DTS Config Drivers Whats good about Zephry / What SUCKS about Zephry Drivers Middle Ware GUI App Layer The Cloud Flags and CTF Patching firmware in the wild

MEP EP#237: Ice Cream Solder Paste EquipotentialParker Cat Feeder Unreminder Started designing the parts and symbols in Eagle. Will post more on twitter as I build the components and put together the symbols Garage Door opener hacking Converting my normal style garage door opener to a “jackshaft” style opener Why? LiftMaster, Chamberlain, Craftsmen are all the same Mine is a Liftmaster Formula 1 Belt drive need to convert to chain drive to attach to the jackshaft All of these use similar drive mechs Other things that are needed Garage door auto lock SureLock Garage Door DeadBolt Cable tension switch LiftMaster 41A6104 Stephen High voltage low current measurement Resistive dividers? Caddock 1776-C681 10M ohm 0.1% tolerance with 0.05% matching Low PPM This method is ok but requires a rather large current sense resistor which is not great. Floating supplies This is how multimeters work. The reference is floating. Isolation solution May go with a

MEP EP#236: Excited ElectronsParker Lead Forming Topic Tools 3D printed forms Best practices? Cat Feeder Unreminder Choosing a solar panel Solar Panels generally act like a current source across its useable power band Specifications that are important Power (Watts) - Max Current @ Peak Power Voltage @ maximum power point (Vmpp) Vmpp - Voltage @ open circuit (Voc) AEM10941 Solar Panel Chip Max V is 5V so open circuit can’t be higher then this MPP is set by 2 configuration pins Ratio between Vmpp / Voc Stephen Voltage References and dev boards MCP1501T-20E/CHY 0.1% initial Accuracy Low noise worst case 50ppm across -40 to +125 Capable of sinking and sourcing 20mA AD584 Dev board 0.3% initial accuracy for the J version. The K version is 0.1% Linear rail is shitty Got 300 mm of knock off chineasium linear rail Sounds like sand in the bearings Held vertically the blocks get stuck…

MEP EP#235: Solar Freaking Cat FeedersParker Cat Feeder Unreminder Pulsing current to light LEDs http://donklipstein.com/ledlocup.html http://www.discovercircuits.com/H-Corner/lowpwrflasher.htm Timer IC LTC2956 Power Management Solar with super capacitors Panasonic BSG series solar panels Will have to do research on specifying solar panels AEM10941 https://e-peas.com/wp-content/uploads/2020/04/DS_AEM10941.pdf Built in LDO regulators Stephen Ball screws Bought a small section of ball screw with the associated nut, nut housing, and end block SFU1605 300mm - 16mm diameter and 5mm pitch Trying to work out linear forces and the RPM range if it were to be driven from a stepper motor or servo Mechanical engineering is tough CNC work Cut the first actual project on the CNC Movable cradle for holding chassis - makes working on them super easy Had to spend some serious time working on getting the machine to cut 90 degree Iterative process Flex in the machine

MEP EP#234: Bashing LEDsParker Didn’t get to work on the Cat Feeder Unreminder but there are lots of interest and ideas in our slack channel! TheStumbler Found a 12hr egg timer. Defeats the purpose of building and learning a new embedded skill. Eric McFall E-Ink for the persistent display. This is a great idea. I will look through my parts bins for a e-ink. Might have one. Derek Does it count as feature creep if the project is still doing the same thing but is way more complicated? Tony W Jack in the box DJ Has been working with Flip Dot displays. Kinda power hungry in short bursts. 4A for only 5ms. Bombledmonk Go solar Sanyo / Panasonic has panels for indoor lighting Stephen Snap dome buttons Interesting requirements for footprints. Not sure how to do it. Snaptron BL-series 0.07 or 0.01” hole for LED - not a whole lot… One week product

MEP EP#233: Good Enough for a BagelParker The Cat Feeder Unreminder Bagel Pin Toaster Controller usable? PT8A2514APE MC14536B 24 stage stage counter with on board RC oscillator Stephen SPI Code Bytes Working on the second PCB revision of a product Code that worked on previous revision didn't work on the new prototype! Changed Chip Select pin for the SPI buss R.F.O. Grant Imahara passes at 49 Maxim is being purchased by Analog for 21 billion dollars

MEP EP#232: Chonky MotherboardsParker The Cat Feeder Unreminder Different implementations to accomplish the goal Stephen Synth DSP replacement Korg MS2000 Was pulling an additional 500mA on the power supply Found a blown surface mount fuse The DSP chip XCB56362PV100 was hot to touch Replaced with part found on ebay Wasn’t sure if this part needed programming LED Matrix Driver - IS31FL3741 39x9 LED matrix = 351 individual color leds or 117 RGBs QFN-24 package 256 levels of PWM control and 256 levels of DC current control Layout vs code R.F.O. Brew Day Updates!

MEP EP#231: Throw The Bacon Across The StageDanny Rankin An instructor in the creative technologies and design program at the University of Colorado Boulder The courses he teaches and his individual research reflect a diverse array of expertise, including graphic design, material fabrication, game design, hardware hacking, sustainable agriculture and large-scale installation art Danny was a guest on MEP episode #171: Mayonnaise Drone (And Other War Crimes) Danny’s experience with teaching during COVID-19 What the end of the semester looked like What is happening now? Summer What does next semester look like How will it be the same? How will it differ? Technology What happens when your education requires technology that is only on campus? The lab What does it look like in the future? Do you expect it will go back to “normal”? Dinosaur Costume Racing

MEP EP#230: We Are All Idiots Together On This PlanetParker Brewery is autotuned and sight gauges calibrated New Alternator for Wagon Brewery is “done” from a build standpoint for this season Parker’s next podcast project Stephen On track to brew on Saturday! Got the whole box built and wired over the weekend Cheapo pump from amazon just arrived today EDA workflow and footprints Do you do things based on the footprint? When is it ok to rely on someone else's footprint? Standards? JEDEC

MEP EP#229: Get Cute This WeekendParker Brewery Lives! Test boil and Process Issues with the current iteration of the brewery What is next Take Inventory of Brew Equipment Spare parts Storage on cart Clean and Fire up Fermentation chamber Clean the brewery Ingredients BREW Future? Motorized valves to simplify the fluid transfer process Drains at bottom of vessels? Better way to change set points on the PID controllers? A/C window unit Wine Chiller Parker Kool 2800 Issues and gotchas for future Stephen My (Stephen's) Jelly Project Cutting panels tomorrow Two cncs at Stephen's disposal That is unfair! Inkscape/Corel Draw for component layout Fusion 360 for CAD/CAM

MEP EP#228: Weapons of Mathewson DestructionWilliam Mathewson An entrepreneur, electrical engineer, and user experience designer for his company William Mathewson Devices otherwise known as WMD Began WMD in 2007 Designed over seventy products that inspire artists and sound designers throughout the music industry Starting A Hardware Manufacturing Company The name WMD How did William arrive at deciding to start WMD? What do y'all do at WMD? The story? How did it all start? Pedals to modular synth Products Fatman Envelope Filter Geiger Counter Distortion Protostar Services Manufacturing Business Hardware is Hard How did this begin? How did you build this service? Best thing about it all Worst thing about it all War stories The future?

MEP EP#227: Ultrasonic Beer Science - Eli Hughes of TzeroEli Hughes The CTO of TZero Research and Development TZero was founded in 2016 by 3 Penn State University graduates who have training and experience in embedded systems, acoustics, mechanical engineering and software Technical background is in electronics, software and acoustics Currently also does work for NXP semiconductors Worked at the Penn State Applied Research Lab where he worked on applications in sensors, condition based maintenance, robotics, undersea vehicles and space science Taught part time in the Penn State University EE Department Plays guitar and keyboard and enjoys woodworking.

MEP EP#226: Chickens and Tea leaves, Al's Simulation RecipeAl Williams One of the authors behind Hackaday, a website that features electronic projects and other things that appeal to people interested in computers, electronics, and technology Ham radio operator Author of many books Has worked on everything from underwater technology to the International Space Station and just about everything in between Was on previous episodes EP#57: Mr. Williams, your book changed my life EP#94: Al Williams and the Field Programmable Gate Arrays EP #160: Al Williams and the One Instruction Wonder Simulations What do you think of simulation? Analog? Digital? Different simulation software LTSpice Xyce from Sandia TINA from TI KiCad integrated spice Microcap 12 EasyEDA FALSTAD LTSpice to Python bridge Hackaday's Circuit VR Where simulated or logical performance doesn’t match real world behavior

MEP EP#225: Clipping and Clamping OpAmpsStephen DC heaters continued Tested the new values Last episode was shooting for ~250mW of dissipation in the regulator and transistor Measuring closer to 350mW Quiescent current and some balancing and tolerance Opamp clamping circuit A useful voltage clamping circuit with independent upper and lower thresholds Pros Much more accurate than the simple clipping circuits Hard turn on characteristics Can be overdriven without much issues Not terribly expensive Downsides 3 or 4 opamps needed Not particularly fast - starts to show issues past 20k and is pretty bad at 30k Small overshoot that is frequency dependent Does not work with opamps that have input protection diodes Parker Brewery Updates! Installed Tubing Pumps Pots Waiting on Stainless mesh basket What is left Design and build the grain crane Mount electrical box Finish wiring Paint and sealant Electrical Box Might have put the power input in the