The MOSFET is used as both a heater and a temperature sensor in a thermostatic circuit...
Using a MOSFET as a thermostatic heater
Simple fixture statically tests programmable-gain amplifiers
The advent of instrumentation amplifiers with digital gain switching offers obvious advantages, such as board-space saving, higher reliability because of fewer solder joints, and lower total cost...
AGC circuit uses an analog multiplier
In the AGC circuit, a 4-quadrant analog multiplier, an amplifier stage, an active, full-wave rectifier, and an integrator accomplish automatic gain control of VIN’s amplitude variations in the audio-frequency range...
LT1635 1A shunt charger
Most battery chargers comprise nothing more than a series-pass regulator with current limit. In solar-powered systems, you can’t count on sufficient headroom to keep a series regulator alive, so a shunt method is preferred...
Ultra-low distortion sinewave oscillator. Part 1
A sinewave is the simplest possible waveform, it is also one of the hardest to generate in pure form. Any impurity represents distortion, and that means added harmonics that make very low distortion measurements impossible...
Finely tune the hue of blue-light sources
When coach cars of long-range trains comprised compartments for six to eight passengers, the passengers could choose either “white” or deep blue light. The blue light helped passengers sleep, even when they were not in full darkness. The circuit lets you set a hue of blue light...
Accurately simulate an LED
Solid-state-lighting applications are quickly moving into the mainstream. Although they are more efficient, the LEDs that produce the low-cost light often require a complicated driver circuit. Testing the driver circuit using LEDs, although easy, yields only typical results...
Battery simulator has variable ESR response
You may lack experience and hardware when designing battery-operated products. The battery life of a product can depend more on the ESR (equivalent series resistance) than the terminal voltage...
9 ppm distortion, quartz stabilized oscillator
A spectrally pure sine wave oscillator is required for data converter; filter and audio testing. Figure provides a stable frequency output with extremely low distortion. This quartz stabilized 4 kHz oscillator has less than 9 ppm...
Photosensing with ambient background
Trying to shield ambient light from your photo circuit is not a trivial task. You would think that you could just cover your circuit with your hands, but that is not a solution: Pulse oximeters depend on the translucency of flesh...