A previous Design Idea describes a simple way to automatically turn off a battery after a preset on period to save battery life. This Design Idea presents a simpler way to perform the same function...
Battery automatic power-off has simpler design
Dual transistor improves current-sense circuit
In multiple-output power supplies in which a single supply powers circuitry of vastly different current draws, two perplexing steps are sensing the current that each output draws and deactivating the power supply in the event of an overload on that output...
Crystal controlled ramp generator
This project originated from the need to produce a linear crystal-controlled ramp signal for an HP 8620C RF sweep oscillator...
Amplifiers perform precision divide-by-2 circuit
The classic implementation of a voltage-halving circuit uses two equal-value resistors. Using 1% resistors provides a divider output with 2% accuracy. For most applications, this performance is cost-effective and more than adequate. However, when you need extreme precision...
Voltage-controlled triangle wave generator
Sawtooth- or exponential-ramp relaxation oscillators are common and generally easy to build. However sometimes a cleaner waveform is desired, and generators of even-symmetric waveforms are a bit more difficult to design...
TinyLoad - Simple Electronic Load based on ATtiny45/85
TinyLoad is a simple electronic constant current dummy load. The ATtiny measures voltage, current and temperature of the heat sink, calculates power, energy and battery capacity, controls the fan and displays all relevant data on the OLED...
Class AB 20-W current booster is insensitive to temperature variations
Class AB amplifiers have been the workhorses of the audio world, thanks to their simplicity, and their ability to deliver high power levels with low distortion. But there are also a number of gremlins that lurk within the AB architecture, mostly in the form of bias instability and other thermally-related issues...
CMOS inverters convert RF to digital signal
Applications ranging from frequency counting and synthesis to sensor signal conditioning require conversion of RF signals to digital-logic levels. In such situations, designers typically use a high-speed voltage comparator to perform the RF-to-digital conversion...
GIC resonator has inherent amplitude control
The circuit is based on a classic generalized impedance converter. The sine-wave-oscillator circuit has inherent amplitude stabilization and normally operates from dual power supplies...
PWM-Based Analog Calculator Provides Four-Quadrant Multiplication, Division
You can build an analog calculator using a pulse-width modulator to perform accurate four-quadrant multiplication and division. While this approach won’t help you ace any math tests, it demonstrates some useful sub-circuits...
