Detect rising edges and cout the time between them

Optoisolators and logic let you know when an object is detected.

Replace classical counters with a microcontroller.

DC-Voltage doubler reaches 96% power efficiency 07/15/2010

Use this DC-DC  converter in application which power efficiency is critical.

• June 2010

You can make an AM-band frequency synthesizer from standard components.

Create a colorful display with red, green, blue LEDS controlled by oscillators and counters.

A PC can capture and process images provided it's powerful enough to keep up with the data flow.

Design a filter controlled through a VCO and PLL.

Bootstrap circuit speeds operation or reduces dc power.

You can use low-on-resistance analog switches to improve efficiency.

You can use this circuit to measure zener voltages as high as 40V.

An external interrupt input catches the missing pulse.

Control power transistors with duty cycles from 2% to 98%.

• May 2010

Four comparators sound a buzzer when water is present or the battery is low.

Use a clock divider to sweep frequency by 20 kHz.

A photoresistor, as part of an optocoupler, provides negative feedback to an op amp, producing a linear response.

• April 2010

When creating microcontroller firmware, you often need to work with data arrays. Tables make easy work of data arrays, such as those for digital-code transformation, correction for sensor linearity, sophisticated calculations, and multiple output organization. Table 1 shows how you can organize data in a table.

Many applications require a circuit to perform pulse modulation and voltage amplification to drive a load with a train of impulses. A typical application is driving a piezoelectric generator in a robot. Other applications include driving small motors or LEDs. Echolocation and ultrasound visualization use a sweeping-frequency, or chirp, signal.

Use a microcontroller and its ADCs to indicate process errors.

Use a single ADC input pin to sense pushbuttons as well as a potentiometer.

Generate a triangular wave for testing other circuits.

Use the MSP430’s port-interrupt-request flags to save switch input transitions for debouncing.

Power three to six LEDs from an ac- or dc-power source and charge a backup battery.

Include this circuit in a switching-power-supply design.

This active circuit represents many battery types.

Use two ICs to produce both waveforms.

How you process images in RAM can eliminate problems with different image sizes.

Logic signals turn motors on and off and change direction.

Create hundreds of patterns with a few timers and logic gates.

Measure voltage drop with a digital voltmeter.

Positive feedback is a typical technique for distributing hysteresis around a comparator, provided that you have a resistive path between the comparator's output and the noninverting input. Positive feedback forms two threshold voltages that have (or assume) fixed values. In addition, they depend on the saturation values of the comparator's output stage.

An oscillator, filters, and comparators detect missing wires in an assembly line.

• Febuary 2010

Generate magnetic fields with a microcontroller instead of mechanical parts.

Timers debounce switches and let you decide when lapses have expired.

Comparators and a voltage-divider network let you set threshold levels.

Produce a stable current for long-term component testing.

Convert data to a more usable format.

DAC uses fewer resistors than that of a previous Design Idea.

Use a binary counter to generate LED-lighting codes.

A crossover-control circuit prevents two or more transistors from powering on at once.

Use behavioral models to simulate circuit elements.

• January 2010

Drive a power MOSFET to 100V dc with this signal-conditioning circuit.

Two Schottky barrier diodes clamp error voltages, cut output glitches.

Turn an unused parallel port into a data port.

Prevent data loss against power blackouts and other interruptions.

Send visible light through strands to check for breaks.

Get the right amount of gain for your op-amp application.