Circuit Break - A MacroFab 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

30 Syys 202053min

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 through hole version This means a lot less wiring is required. EDA schematic and grounding

23 Syys 202053min

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 as mechanical supports Designing a Pawl system to clasp the pcb Next Revision Make the landing pads bigger Add something for strain relief Move the pins slightly down for more spring Add more anti rotation pins

17 Syys 202047min

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 Want to have “multi-meter” banana connector History of the banana connector Technically a binding post

9 Syys 202049min

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

2 Syys 202040min

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 60uV/mA so 0.1mA would be 6uV….. This may still not be the best solution because I would likely need a ton of gain and have to correct for any offsets. Possibly to a tro prong approach - Measure voltage across known resistances in the circuit Getting transformers manufactured for your product What do you need to know? How do you get started? What are the specifications Mains transformers SMPS and flyback style “yellow tape” Transformers.

26 Elo 202050min

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

19 Elo 20201h 20min

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 an isolated solution - basically a power supply that isolates the secondary. Isolated digital communication down to LV side. Tests for pcb shielding Did a shield plane test on a new pcb assembly. Top and bottom pours that respect clearance rules. 5mm pitch via stitching. All terminate to one pin on a 2 pin header. Second pin connects to a plated bolt hole that goes to chassis.

12 Elo 202057min