Figure’s negative constant current source has been a textbook application for the LM337 regulator forever...
A negative current source with PWM input and LM337 output
Simple logic probe uses bicolor LED
When probing digital logic levels on a circuit board, locating the indicator of the logic level near the probe tip is convenient, so that you can keep both the indicator and probe tip constantly in sight...
Digital potentiometers enable programmable biquadratic filter
Of the many types of analog filters available to designers, few allow easy adjustments of the filter parameters. The biquadratic, or biquad, filter is an exception, however...
PWM-programmed LM317 constant current source
LM317 fans will recognize Figure as the traditional LM317 constant current source topology...
Test technique quantifies jitter of discrete-comparator design
A colleague asked for the measured jitter number on a single-supply comparator design based on the LM359 IC. He wanted to know how the jitter performance of the discrete comparator compared to an IC comparator, which was used with an ultrasound application...
Infrared (IR) receiver circuit minimizes power consumption
Receiving infrared signals while conserving system power is difficult, and typically requires the inclusion of complex power-management routines in the firmware. You can avoid that problem by disconnecting power to the microcontroller when IR is not present...
Photo tachometer sensor accommodates ambient light
Tachometry, the measurement of the speed of spin of rotating objects, is a common application. Some of those objects, however, have quirky aspects that make them extra interesting, even scary...
Reduce EMI by sweeping a power supply's frequency
Switching power supplies can be notorious noise generators. You should prevent this noise, which is conducted, radiated, or both, from returning to the input source...
Infineon CoolGaN power transistors enable SounDigital to reach higher fidelity in smaller amplifier systems
Manufacturers of cutting-edge audio equipment constantly seek to enhance sound quality while also meeting the growing demand for compact, lightweight, more integrated, and energy-efficient designs...
Water-leak detector uses 9V batteries
A previously published Design Idea describes a practical gadget that has the potential to save a lot with little investment. However, the circuit uses 120 V line voltage and, as such, it is not that convenient for many applications...
