Automated battery charger calibration fixture using Holtek’s ASSP MCUs. Link here (PDF) Power chargers for electric bicycles, electric motorcycles and power tools, etc., are all calibrated before delivery, thereby correcting any charging parameter drifts due to external component tolerances. This will ensure the output voltage and current conform to their specifications. However, traditional applications are […]
Author Archives: DP
App note: BA45F55xx with power line transceiver
App note from Holtek on power line transceiver found on their BA45F55xx MCU. Link here (PDF) A Power Line Transceiver is a fire protection dual-line bus which is used as a data transceiver. The master gives a command to the slave using a voltage signal modulation method while the slave responds to the master using […]
DIY universal PID controller
DIY tutorial on building your own universal PID temperature controller @ breadandammo.com.
App note: Op amps for MEMS Microphone preamp circuits
App note from TDK on design considerations of preamps used on MEMS microphones. Link here A microphone preamp circuit is used to amplify a microphone’s output signal to match the input level of the devices following it in the signal chain. Matching the peaks of the microphone’s signal level to the full-scale input voltage of […]
App note: Analog and digital MEMS microphone design considerations
App note from TDK about the things to consider when integrating analog and digital MEMS microphones into a system design. Link here (PDF) Microphones are transducers that convert acoustic pressure waves to electrical signals. Sensors have become more integrated with other components in the audio signal chain, and MEMS technology is enabling microphones to be […]
A sensitive, frequency-modulated dip meter capable of measuring resonator Q
Qrp Gaijin’s version of a dip meter to measure resonator Q: A highly-sensitive, narrow-band frequency-modulated dip meter offers a simple way to measure resonator Q. I have been working with an unusual dip meter circuit recently that has some interesting properties. The dip meter, also called a grid dip meter, is a simple homebrew instrument […]
Reverse engineering RAM storage in early Texas Instruments calculator chips
Reverse engineering RAM storage in early Texas Instruments calculator chips: Texas Instruments introduced the first commercial single-chip computer in 1974, combining the CPU, RAM, ROM, and I/O into one chip. This family of 4-bit processors was called the TMS1000. A 4-bit processor now seems very limited, but it was a good match for calculators, where […]
Powering up an HP YIG tuned oscillator
Kwong explained the operation principle of an YIG tuned oscillator and demonstrated the tuning characteristics: I was going through some of the components I accumulated over the years and stumbled upon a Hewlett Packard YIG tuned oscillator (part number 5086-7023) that I bought a while back. This YIG oscillator was made for a frequency extension […]
App note: Driving electronic paper displays (E-paper)
Silicon Labs’ app note on driving E-paper with their EFM32 micro. Link here (PDF) Electronic Paper Displays (EPDs) are types of displays that are reflective and bistable. Reflective in this case means that they rely solely on ambient light and does not use a backlight. Bistable is the property of retaining an image even when […]
App note: Designing with an inverted-F 2.4 GHz PCB antenna
PCB design guide for an inverted-F 2.4 GHz antenna from Silicon Labs. Link here (PDF) One of the main reasons to use a PCB antenna is to reduce cost. Since the antennas are printed directly on the board, they are generally considered to be free. On boards with room to spare, this will be true. […]
App note: Secure hash algorithms back to basics
Maxim Integrated’s introduction to SHA security. Link here (PDF) This application note goes over the basics of Secure Hash Algorithms (SHA) and discusses the variants of the algorithm. It then briefly touches on how the algorithm is used for authentication, including the concept of a Hashed Message Authentication Code (HMAC). It concludes by looking at […]
App note: Optocouplers in on-board chargers and battery monitoring systems
App note from Vishay on how optocouplers play a role on safety for Electric vehicles. Link here (PDF) The number of electric vehicles on the roads is steadily growing, increasing the need for safe and reliable battery systems and high efficiency battery chargers. Modern electric vehicles use battery systems with voltages up to 1000 V […]
Reverse-engineering the classic MK4116 16-kilobit DRAM chip
Ken has written an article on reverse-engineering the classic MK4116 16-kilobit DRAM chip: Back in the late 1970s, the most popular memory chip was Mostek’s MK4116, holding a whopping (for the time) 16 kilobits. It provided storage for computers such as the Apple II, TRS-80, ZX Spectrum, Commodore PET, IBM PC, and Xerox Alto as […]
FV-1 based mini SDR radio
FV-1 based mini SDR radio @ circuitsalad.com: I have really enjoyed my FV-1 based mini SDR radio but it has one problem…its too small! I made the thing so small; it’s hard to operate and assemble. So I decided to make it a little larger, allowing for all the controls to be larger and more […]
App note: Control solution using logic, analog switches, and discrete semiconductor devices for reversing a one-phase motor
App note from Littelfuse on solution to control split-phase motor using logic devices and triacs. Link here (PDF) In the huge variety of the AC motors, one-phase motors are an excellent option when only the single-phase power is available to supply electrical energy which motors require to operate. One of the most common single-phase motors […]
App note: Circuit protection solution for lithium cells
App note from Littelfuse on PolySwitch PPTC for lithium cells protection. Link here (PDF) Primary lithium cells (i.e., AA and 2/3A) and rechargeable lithium cells (i.e., 18650, 17500, and prismatic) are used in many portable electronics applications, such as laptop or notebook computers. Their popularity is based on the fact that they offer high energy […]
Reverse-engineering the carry-lookahead circuit in the Intel 8008 processor
Reverse-engineering the carry-lookahead circuit in the Intel 8008 processor: The 8008 was Intel’s first 8-bit microprocessor, introduced in 1972. While primitive by today’s standards, the 8008 is historically important because it essentially started the microprocessor revolution and is the ancestor of the modern x86 processor family. I’ve been studying the 8008’s silicon die under the […]
App note: How to determine if an eFuse system can be safely hot−plugged
This app note from ON Semiconductors linked here (PDF) System designers must account for voltage surges that occur when supplies or loads are connected. eFuses are integrated circuits with many features to protect loads from these surges. However, it is important to ensure that the eFuse itself will not receive excessive voltage on its input. […]
App note: Analysis of power dissipation and thermal considerations for high voltage gate drivers
App note from ON Semiconductors on ways to dissipate thermals or reduce junction temperature of HVIC. Link here (PDF) Gate drivers used to switch MOSFETs and IGBTs at high frequencies can dissipate significant amount of power depending on the operating conditions. It is important to determine the driver power dissipation and the resulting junction temperature […]
Low-cost open source ventilator-ish device
Johnny made a low-cost ventilator-ish device, that is available on GitHub: In the event that COVID-19 hospitalizations exhaust the availability of FDA approved ventilators. This project documents the process of converting a low-cost CPAP (Continuous Positive Airway Pressure) blower into a rudimentary non-invasive pressure support ventilator that could help with breathing during respiratory distress. It’s […]