Author Archives: DP

Lab power supply build using old power bricks

Building a lab power supply from old computer power bricks: Over the years, I have accumulated many used computer power bricks. Although I could just use them by themselves to power other electronics with similar voltage and current requirements, I thought I would combine a few of them together as the input to a linear […]

Reverse-engineering a low-power LED flasher chip

Ken writes, “How do you make an LED blink? A vintage way is the LM3909, a chip from 1975 that can flash an LED for a year from a single flashlight battery. This chip has some surprising features, such as a charge pump that lets you power a 2-volt LED from a 1.5-volt battery. This […]

App note: MOSFETs withstand stress of linear-mode operation

App note from IXYS talking about MOSFET operating in linear region in application like electronic load. Link here (PDF) Power MOSFETs are most often used in switchedmode applications where they function as on-off switches. But in applications like electronic loads, linear regulators or Class A amplifiers, power MOSFETs must operate in their linear region. In […]

App note: Digital inrush controller

App note from IXYS about their unique digital inrush controller using Zilog’s 8-bit Z8F3281 MCU. Link here (PDF) Digital control allows distinctive solutions to control inrush current in typical AC-DC rectifier with capacitive load by limiting capacitor pre-charge current to a predetermined value at each half sine-wave cycle. Capacitor charge is spread over a number […]

Adjustable Lab power supply

Xristost built a DIY adjustable lab power supply: With the original schematic at hand I took the liberty to make a few changes. First of all I replaced two transistor-zener regulators with LM317L/LM337L. Circuits are calculated to produce 33V positive and 3V negative voltages. Thus total supply voltage for the opamps does not exceed 36V and […]

DIY current sensor capable of handling up to 15A

Utsav shared detailed instructions of how to build your own current sensor that can measure up to 15 Amps, project instructables here: This current sensor can easily be used for measuring currents up to 15 Amps constant and can even handle about 20 Amps peak. I had previously built a shunt current measurement module using […]

High efficiency 4V supply QRP amplifier

Low voltage, high efficiency QRP RF amplifier project @ circuitsalad.com This is an example of a high efficiency QRP transmitter designed to work at very low supply voltages (3v-5v). It can produce 2 watts a 4 volt supply @ 70% efficiency. It uses small, inexpensive switching mosfets. The primary requirement for these mosfets is low […]

App note: Bipolar transistors maximum ratings

Deep dive on to the maximum ratings of bipolar transistors presented in this app note from Toshiba. Link here PDF! For transistors, the maximum allowable current, voltage, power dissipation and other parameters are specified as maximum ratings. The absolute maximum ratings are the highest values that must not be exceeded during operation even instantaneously. When […]

App note: Comparison of SiC MOSFET and Si IGBT

App note from Toshiba on the advantages of Silicon carbide (SiC) MOSFET over silicon (Si) IGBT. Link here PDF! Silicon carbide (SiC) comprises silicon (Si) and carbon (C) atoms. Each atom is surrounded by four different atoms in the form of a regular tetrahedron. SiC is a compound semiconductor with the densest tetrahedral arrangement. SiC […]

Cloning the ET-3404 6809 adapter for the Heathkit ET-3400

Dr. Scott Baker made the ET-3404 6809 adapter clone: I’ve become somewhat of a Heathkit ET-3400 enthusiast lately, after building my ETA-3400 memory/io clone. I decided to also clone the ET-3404, which is a 6809 adapter board for the ET-3400. Why? Simply for completeness sake. The official “experiments” for the ET-3404 aren’t all that exciting, […]

Laser cut project plate

Layne designed a laser-cut project plate: When I build electronics prototypes, it’s sometimes difficult to keep all the parts together without falling apart, especially if you need to move everything from one location to another. Between the breadboards, Arduino boards, programmers, FTDI cables, spare wires, and spare parts, I wanted to create a way to […]

Building a chaotic oscillator from common components

Tim blogged about his chaotic oscillator build: A chaotic oscillator is an electronic circuit that can exhibit “chaotic“, nonperiodic behavior. A commonly cited example is Chua’s circuit, but there are many others. I always regarded these as carefully designed, rather academic, examples. So I was a bit surprised to observe apparently chaotic behavior in a […]

App note: Load switches for mobile and computing applications

App note from Nexperia presenting simple load switches in mobile and computing applications. Link here (PDF) There are several reasons why a circuit or subsystem is required to be disconnected from the power supply using a load switch. A very simple and very common reason is that it helps saving power. An unpowered subsystem can […]

App note: Driving solenoids in automotive applications

App note from Nexperia about various solenoid driver used in automotive. Link here (PDF) There are a wide variety of solenoid drive circuit topologies. Most of them use MOSFETs in various configurations and driving modes. In this application note four of them will be discussed: solenoid driver with free-wheeling diode, solenoid driver with MOSFET avalanching, […]