Like many others, I was quite amazed to learn about a microcontroller sold for only 0.03 USD via the EEVblog last year. How was this possible? Many assumed this was a fire sale of an old product. Digging a bit further, it became apparent that there is an entire market segment of ultra-low-cost microcontrollers. Almost all of them are products of rather unknown companies from China or Taiwan. This write up summarizes my findings in this rather peculiar niche.
Electrophoresis power supplies are commonly found in biology and other life sciences laboratories. These power supplies are usually capable of supplying high voltages and high currents required for gel electrophoresis–a method used for separating DNA, RNA and other protein fragments based on their size and charge. There are many used electrophoresis power supplies out there in the second hand market and can be bought quite cheaply. I am curious whether these electrophoresis power supplies are suitable for electronics lab use as a lab grade high voltage power supply can be quite expensive. So I recently picked up one from eBay to take a look.
Good read on this app note from Silicon Labs comparing their low power but obsolete timer. Link here (PDF)
The 555 timer is the workhorse of ICs, with close to a billion of them manufactured every year. Introduced in 1972, the 555 is still in widespread use because of its ease of use, reasonable price, and good stability. It can be found in a wide variety of applications for oscillation, timing and pulse generation. But what if you need a timer IC for ultralong life, low-frequency battery-powered/portable applications where a low supply current is a requirement? Is the CMOS555 timer your best option?
Q-pump an alternative to inductor charge pump boost regulator for low power and sleepy microcontroller from Silicon Labs. Link here (PDF)
In the switch-mode power supply world, capacitor-based charge pumps (or Q-pumps) generally aren’t useful for heavy lifting, but work well in niche micropower applications where space is at a premium. They work best in applications where the output voltage is an integer multiple of the input voltage, which are operating points that result in peak efficiency. However, they can also shine when powered from a variable input like a battery, particularly when quiescent battery drain is more important than heavy-load efficiency. This might be the case when powering a microcontroller that spends most of its life sleeping.
The Sweeperino a very useful Arduino based test instrument. It is the following:
*A very stable, low noise signal generator from 4 MHz to 160 MHz without any spurs
*A high precision power meter with 90 db with 0.2db resolution
*A sweeper that can be your antenna analyzer, plot your crystal or band pass filter through the PC
*It fits in your jacket
*It can be assembled in an evening
*Costs about $50 in new parts
This article describes the “Cigarette Pack” SSB QRP transceiver” for 14MHz that I first had mentioned some months before. Recently, when taking it from the shelf, the transceiver dropped to the floor and was severely damaged. This lead to serious defects in the front panel area, the main frame, the cabinet and so on. The interior parts were, luckily, not affected by the crash. So, I had to revise the whole radio, make a new front panel and cabinet, ply the frame straightly (as far as possible) and so on. This is the full description of the rig now to complete the files here. The good news: The radio is fine again and fully operational! And the even better news: I still have not started smoking!
Presenting the usage of Core independent paripheral of PICs in this app note from Microchip. Link here (PDF)
It is possible to find out whether a measured signal is below or above a certain value/reference using a single comparator. But, what if the desired interval is between two values, the undervoltage and overvoltage protection?
The most convenient and fastest solution is to use two comparators and two references. The results are analyzed to decide which of the three intervals houses the measured signal. Using an Analog-to-Digital Converter (ADC) and core post-processing will yield the same result, but the process is slower and dependent on core availability.
Here’s an app note about PSRR of LDO from Microchip. Link here (PDF)
The Power Supply Rejection Ratio is the ability of a device, such as a Low Dropout Voltage regulator, to reject the various perturbations that can be found in its input supply rail by providing a greatly attenuated signal at the output. Generally, the main source of the perturbation will be the output ripple of the DC/DC converters that typically power LDOs.
High PSRR LDOs are recommended for powering line ripple sensitive devices such as: RF applications, ADCs/DACs, FPGAs, MPUs, and audio applications.
One important clarification must be made: PSRR is NOT the same with output noise. PSRR is a measure of rejection. It shows what the part will output based on the given input.
I’ve been an avid user of ST’s F0 series ever since it was launched. The 48MHz Cortex M0 is almost always the perfect MCU for every project that I tend to build and it’s so easy to program and debug that, for me, it’s the default answer to ‘which MCU should I use for this project?’ So when I noticed that ST had launched a ‘G0’ range I just had to have a closer look.