Swap out your LDO for a switcher today, with these designs for a modern take on the TO-220 mounted LM1117 and 78xx series LDO regulators! This project is my take on a quick and easy replacement for the 3-pin LDO. The aim is to replace TO-220 linear regulators with a switching converter, in pursuit of higher efficiencies and current capacity.
Using a Recom RPX series DC-DC module for its small size and incorporating SMD feedback resistors and bulk capacitance on board allows for a drop-in replacement to existing LDO designs, while remaining in the same overall footprint as the counterpart.
As LM1117 LDOs have a different pinout to the 78xx series of regulators, I designed two versions of the layout.
If you want to hack around with the communication protocol that USB Power Delivery devices use to negotiate their power requirements with the upstream source, a tool like Google’s Twinkie really helps. With it you can sniff data off the line, analyze it, and even inject your own packets. Luckily for us, the search giant made the device open source so we can all have one of our own.
Unfortunately, as [dojoe] found out, the Twinkie isn’t particularly well suited for small-scale hobbyist manufacturing. So he came up with a revised design he calls Twonkie that replaces the six layer PCB with a much more reasonable four layer version that can be manufactured cheaply by OSHPark, and swaps out the BGA components with QFP alternatives you can hand solder.
[Attoparsec] has been building intriguing musical projects on his YouTube channel for a while and his latest is no exception. Dubbed simply as “Node Module”, it is a rack-mounted hardware-based Markov chain beat sequencer. Traditionally Markov chains are software state machines that transition between states with given probabilities, often learned from a training corpus. That same principle has been applied to hardware beat sequencing.
Each Node Module has a trigger input, four outputs each with a potentiometer, and a trigger out. [Attoparsec] has a wonderful explanation of all the different parts and theories that make up the module at the start of his video, but the basic operation is that a trigger input comes in and the potentiometers are read to determine the probabilities of each output. One is randomly selected and fired. As you can imagine, there are loops and even dead-end nodes and for some musical pieces there is a certain number of beats expected, so a clever reset signal can be sent to pull the chain back to the initial starting state at a regular interval. The results are interesting to listen to and even better to imagine all the possibilities.
I have a couple of new PCBs being made by OSHPark . They are awesome as usual and have kept up during this pandemic. Which is a tuff thing to do. The first PCB is my IOBuddy shrunk down to smaller size. Its called the AtomIO
As you can see from the render it has 3 Outputs (LED) and 2 Inputs (BTN). It’s tiny as heck and will help keep breadboards less full. The LEDs are tied to GND with a Resistor so all you have to do is supply 2v to 6v to turn them on. The buttons are pulled low via 10k – 22k ohm. So when pressed they output a HIGH signal. What ever is on the power rail it is connected to.
The next board I have on the way is more of an internal use PCB but may sell it if wanted enough. its a simple breakout for those memory LCDs from sharp. The LS027B7DH01 to be exact. I call it the AtomSharp.
The nRF9160 Feather by Jared Wolff (aka Circuit Dojo LLC) is an electronics development board. It features tghe nRF9160 by Nordic Semiconductor. This part is capable of both CAT M1 LTE and NB-IoT for communication with the outside world. It’s compatible with the Zephyr RTOS which is fully baked into Nordic’s nRF Connect SDK. Other toolchains and languages coming soon to a Github repository near you.
Jorvon Moss, known on Twitter as @Odd_Jayy, recently showed off his second pair of Magpie goggles with the tweet: “And this is why people called me odd growing up.” I reached out to him and he explained that the glasses were “a fun gadget that he put together really quickly over a weekend.” He programmed the 3D-printed mechanical device to open and close the irises and raise and lower separate eyebrows, using an Adafruit Trinket and two servo motors. More mechanical than digital, the goggles become part of a costume, and Jorvon becomes his own character. “Every sci-fi movie always had a really cool person with goggles,” Moss told me.
A video of him wearing the Magpie goggles “became a lot more popular than I thought,” he said. His Twitter followers, many of them makers he has gotten to know, cheered him on.
Moss began building robots about five years ago when he was in college. Like a lot of makers, he started doing it before he understood what he was doing, like artists who start drawing, even though they haven’t had a lot of training.
“Dexter is my personal favorite. And the thing about Dexter is that I’m always improving him. I’m always upgrading him. In a lot of ways, he’s growing up and a lot of people see him as my child.” Dexter is on V6, with over 160 components. He wants Dexter to become a wearable robot without the need of a backpack to carry various components. “I am designing a way for that to no longer be an issue,” he says.
The Earth Day Challenge is now under way! Spin up your take on an Earth-Day-themed electronics project and you’ll be in the running for one of the three $200 shopping sprees at Digi-Key, who are sponsoring this contest.
This is all about raising awareness for environmental projection. You might considered something as direct as measuring and plotting air quality data, or as abstract as weighing your home’s recycling bin and garbage bin and making a game out of generating less waste in general, and boosting your recycling-to-landfill ratio. Find an application that can be moved from grid-power to solar power, or build a carbon-savings counter that calculates the impact you have when choosing your bike over a car. The coolest projects are the ones that make us all think in new ways.
In addition to those $200 prizes for the top three projects, there are $50 Tindie gift cards for the twelve most artistically presented projects. Digi-Key is looking for great images to include in a wall calendar for 2022.
We recently did a test panel in anticipation of launching a 6 layer service. Jay Carlson took the opportunity to design a tiny breadboard-friendly board called the mxiot:
So what exactly was that 6-layer @oshpark PCB I was showing off earlier? It’s a small breadboard-friendly embedded Linux board I’m planning on open-sourcing once the design is verified. Here it’s pictured next to a Pi Zero, just to give you an idea of how tiny it is.
This board uses the $2.68 http://i.MX 6ULZ, a 900 MHz Cortex-A7. This part is specifically designed for smart-speaker-type applications and lacks the LCD/CSI/Ethernet controller found on the other http://i.MX 6ULL parts.
I’ve always wanted to do a small-form-factor embedded Linux breakout board, but it felt silly laying down a beefy part without ethernet or any of those big parallel multimedia interfaces available. The ULZ has none of that, so it’s a guilt-free form factor for the part.
This one supports standard 40-pin SDIO WiFi/BT modules, so you’ll have options for 802.11n or ac, and BT 4.0-5.0. I’m cheap, so I’ve mounted the RTL8723BS on these two.
The biggest reason you’d have to go from 4L to 6L for designs like this is when you have to cram parts together. You don’t need HDI interconnects (since these are still huge-ass 0.8mm-pitch BGAs), but you definitely need internal routing layers.
The other reason to go to 6 layers is just ease of routing — this design only took a few hours to throw together. Most of the day was spent fretting in the pinmux tool over which pins to bring out to the headers and what should actually be on the board.
OK, so why would you want this instead of a Pi Zero, ARM9, or Cortex-A5 board? This one has a Cortex-A7 on it, so won’t run into as many compatibility issues with Node.JS, .NET Core, or other software packages useful for IoT projects.
In addition to the onboard WiFi/BT, RGB LED, button, and USB connectors, the board has an I2S interface (with separate signals for RX and TX paths, plus SPDIF), 4 PWM channels, 4 12-bit ADC inputs, SPI, I2C, a console UART, a full UART (good for LTE modems), and a spare UART/I2C.
Just did a quick fit on a breadboard to make sure I didn’t have any clearance issues with the thru-hole USB connector. This thing is tiny! And yes, you get two free rows of breadboard pins on either side.
Parts for the bottom side didn’t arrive until today. My 0402 placement is drunk af, but a little heat and these guys pop right into place.
OK, onto bring-up: these buck converters don’t kick on until 2.7V, so you won’t see any current usage before that. Once current was flowing, I measured my 1.35V rail to make sure it wasn’t getting 100% duty-cycled to the input, which can happen if the FB pin isn’t connected
Exposing my 1.35V rail to 2.6V wouldn’t be great, but it’s a lot better than definitely frying it with 5V. Alright, the only other rail, 3.3V, can be verified the same way. Once that’s done, ramp it up to 5V and sanity-check the current consumption across all the assembled boards
(by the way, ramping up your supplies really slowly can put chips in weird states, so make sure to give it some fresh power to ensure your power sequencing is working)
Like many application processors, the iMX6ULZ has a boot ROM that will instantiate as a USB device if attached to a computer. This HID device popped right up when I connected it to my computer, so I know core regulators work, the POR circuitry works, and USB pins aren’t shorted.
Usually, I’d get U-Boot working at this point, but I was recently reminded that NXP has a Windows GUI app that will stress-test your board over USB. Since PCB CAD is heavily Windows-based, it’s nice that hardware folks can test their board without needing to fire up a Linux VM.
Aaaaaaand it boots! Kind of. I need to get a U-Boot port and device tree going for the board, and there appears to be a weird MMC driver bug in U-Boot right now, so I had to steal a binary from a friend (thanks @EvanHailey!) to get things going. But it’s alive!
OK, I’ve verified enough of this design to feel comfortable pushing it out the door. Here it is!
Since people appear to actually be looking at this, I cleaned up the BOM a bit and added it to the docs. Down to 27 lines, but if you use 10uF caps on all the 0603 pads you’d be down to 25. You could probably get away with 5k1 resistors on all 1-10k spots. down to 23. Not bad!
With the 3.3V regulator so close, the 47uF on the MicroSD could become a 10uF. Down to 22 lines. Don’t need an RTC? Then nix Y2. Now at 21 lines. Of course, the board would boot fine without the LED or pushbutton, and I haven’t even mounted the QSPI flash yet. BOM: 18 lines.
The whole “premature optimization” warning that everyone parrots to each other is so tired. I’m a big fan of aggressive BOM optimization early on if there’s a remote chance I’ll be hand-assembling any prototypes. BOM lines kill productivity at every step of the prototype process.