Years ago I heard about the OpenDPS project to give open source firmware to cheap and available chinese power supplies. These aren’t strictly whole power supplies, they are configurable CC and CV buck converters. That means that it needs a stable DC source to back it to be used as a bench power supply. Perhaps you may not want to do this if you intend to use the DPS as a battery charger run from a solar supply or something, but most people I see want to use them for bench supplies so that requires an existing DC supply. Today I finally finished mine.
The 2.4″ I2C OLED display I had sitting idle is too big for the “Promini OLED Clock shield”, yet a perfect candidate for a regular Arduino shield. This is how it looks soldered on a prototype shield with two buttons on top, attached to wsduino running the OLED Clock sketch
App note from Maxim Integrated about low current and voltage battery monitors. Link here
Many of today’s portable consumer electronic devices are powered by small button or coin-cell batteries. Users, of course, expect long battery life and reliable charge-level information. However, it can be quite challenging to efficiently monitor the health and state-of-charge (SOC) of these batteries without significantly affecting said SOC. In this application note, learn how simple, low-power monitoring circuits for small batteries can address this challenge.
App note from Maxim Integrated demonstrating the effects of different resistor tolerances on the analog front end of ADC’s performance. Link here
This application note explains how the different tolerances of the same value resistors at the inputs can alter the THD performance of the fully differential ADC. The cost of resistors changes significantly with each lower increment in tolerance
What is the cheapest receiver you can make for VHF? Here is a candidate where all you need to do to modify a small FM headphone receiver is to desolder one end of two capacitors, and connect a short cable with an antenna connector.
So, two little switching power supplies, one for the DOB-50 and CTC-5 as they have similar operating voltages, and one higher voltage one for the DOB-80, a simple op-amp comparator to output the pulses to an Arduino to process and display the results. The power supplies are controlled using two MC3406AD’s, driving an IRF840. I’ll just refer to the component numbers on the top supply, the bottom one is almost identical. The back EMF from the inductor L2 is rectified by a UF4007. There’s a feed back loop, R14,15 & 16 and the pot is used to adjust the HT..
Single chip high efficiency step-down converter, app note from ON Semiconductors. Link here (PDF)
The LV5980MC is a fixed 370 kHz, high−output−current, Non−synchronous PWM converter that integrates a low−resistance, high−side MOSFET and a Customer Chosen, External Diode for the rectification. The LV5980MC utilizes externally compensated current mode control to provide good transient response, ease of implementation, and excellent loop stability. It regulates input voltages from 4.5 V to 23 V down to an output voltage as low as 1.235 V and is able to supply up to 3.0 A of load current. The LV5980MC includes Power Save Feature to enhance efficiency during Light Load. In low consumption mode, the device show operating current of 63 A from VIN by shutting down unnecessary circuits.
ON Semiconductor’s app note featuring 12V 12W adaptor design using NCP1362 primary side regulation controller with valley lockout that hold its switching frequency at light loads. Link here (PDF)
Quasi−square wave resonant converters also known as Quasi−Resonant (QR) converters are widely used in the adaptor market. They help designing flyback Switched−Mode Power Supply (SMPS) with a reduced Electro−Magnetic Interference (EMI) signature and improved efficiency.
The blog post details a new CNC controller I designed. I have probably designed 40-50 different controllers over the years, but this one has me really excited. My past controllers were generally application specific. My recent controllers have all been for the Grbl_ESP32 firmware. The I/O on the ESP32 is very flexible, but somewhat limited in pin count. There have always been enough pins to control the machine, but not enough to make a general purpose CNC controller that can target any machine.
I’ve always wanted a Hayes Chronograph, but have never been able to acquire one, so I finally broke down and just made my own. The Hayes Chronograph was a compliment to Hayes line of smart modems, and implemented a real time clock for computers that didn’t have a built-in clock. They were popular in the early 1980s, and became less popular as computers began to either come with clocks built in, or add-on boards with clocks became popular. My “remake” keeps the theme of having a Vacuum Fluorescent Display (VFD), but switches to a GPS as a source of time synchronization. A raspberry pi is used as control — this thing could be used as an NTP server!. My design retains the DB25 for communication with the host computer, and attempts to replicate the original Hayes protocol.
μSim is a lightweight PIC™ CPU and ALU simulator. This simulator supports the PICmicro mid-range instruction set and designed to work on both PC and Arduino platforms. Compare with most of the other emulators, μSim does not provide all MCU features and peripherals. This simulator design as a minimalistic system, and based on the requirements, it can extend with additional peripherals and features.
App note from FTDI/Bridgetek demonstrating LED control over Ethernet. Link here (PDF)
In an increasingly connected world, more and more devices are going online. To enable online connectivity typically requires an MCU with Ethernet or Wi-Fi capabilities. To demonstrate the principle, this Application Note describes an implementation of a web server which allows for control of 2 WS2812 serial addressable LEDs. A web server is implemented on an FT90X device which when connected to a Local Area Network (LAN) allows a web browser to control the LEDs on an MM900EVxA board from a graphical web page.
Couple of years ago I purchased from a local store 100 MHz crystal resonator and tried several times to make a working schematic on breadboard using standard circuits I found on the internet. It never worked good enough, usually oscillating at 33.3 MHz instead of 100 MHz. Finally, I found that the crystal is third overtone type.
With this latest redesign, I made a few more changes. First of all, I decided I would no longer be afraid of LoRa and put in a LoRa radio module. This will, with the right firmware, allow for standalone operation using LoRaWAN and The Things Network. It will also allow for much longer range, with its lower 900MHz frequency, with some slightly higher power consumption. I can continue using it with my Raspberry Pi point-to-point setup as well.
We’re coming up on a confluence of two things: Nice weather, and relaxing of the Covid-19 lockdowns in much of the United States. This means more hams leaving their home shacks and taking their operating to the field. For some, this means climbing mountains and doing SOTA activations. For others, this means hiking on trails, and doing POTA activations. For yet others, this means gearing up for Field Day, or doing HF Pack operating, with a manpack station on their back. But no matter what they actually choose to do in the field and why, all of them have a similar need.
High speed board design app note from ON Semiconductor. Link here (PDF)
There is an increase of devices and circuitry in usage of high speed, low consumption, small volume and lower interference. Hence PCB design is an important stage of electronic product design. It forms a connection between function and electronic components, and is also an important part of power circuit design. High frequency circuit has the higher integration and the higher layout density, making it necessary to know how to make layout more reliable. The use of multilayer board becomes a necessity and an effective means to reduce cross interference of signals, better grounding and lower parasitic inductance.
This application note looks at the different layout types, practices and guidelines, types of material and factors influencing the high frequency signal transfers.
Tech note from Vishay on polypropylene film capacitor value calculation with temperature and power dissipation consideration. Link here (PDF)
Film capacitors can deliver high power density due to their low ESR and high ripple current capabilities, and offer the highest ampere per μF ratio of capacitor technologies. This feature, combined with their high reliability and long lifespan, make the film DC-link capacitor a central component for power inverters in industrial and automotive applications.
When the MechBoard64 was finally realized and presented on my blog, it soon came clear that a new mechanical keyboard was the missing piece in the creation of a brand new Commodore 64 (…well that and some new keycaps…). As I have no intention to become a Commodore 64 mechanical keyboard manufacturer, I’ve therefore decided to release all information regarding the creation of the MechBoard64 . This includes files for creating the keyboard PCB (Gerber, Excellon, BOM), the keyboard bracket (Illustrator, PDF, bend allowance drawing), 3D printed keycap adapters (.STL), the keyboard stabilizers (dimensions, material) and all miscellaneous parts (cables, screws, nuts, super lube). This way users can make their own keyboards, modify them to accommodate modern day keycaps, make groupbuys or start making batches for everyone to enjoy
Every Tuesday we give away two coupons for the free PCB drawer via Twitter. This post was announced on Twitter, and in 24 hours we’ll send coupon codes to two random retweeters. Don’t forget there’s free PCBs three times a every week:
Hate Twitter and Facebook? Free PCB Sunday is the classic PCB giveaway. Catch it every Sunday, right here on the blog
Tweet-a-PCB Tuesday. Follow us and get boards in 144 characters or less
Facebook PCB Friday. Free PCBs will be your friend for the weekend