Detect rising edges and cout the time between them
Count objects as they pass by 07/15/2010
Optoisolators and logic let you know when an object is detected.
Replace classical counters with a microcontroller.
Use this DC-DC converter in application which power efficiency is critical.
Low-cost RF synthesizer uses generic ICs 06/24/2010
You can make an AM-band frequency synthesizer from standard components.
Tricolor LEDs create a flashing array 06/24/2010
Create a colorful display with red, green, blue LEDS controlled by oscillators and counters.
Image-capture system uses USB and LabView 06/24/2010
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 solenoid actuation 06/10/2010
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.
Detect missing pulses to avoid losing data 06/10/2010
An external interrupt input catches the missing pulse.
Control power transistors with duty cycles from 2% to 98%.
Water-leak detector uses 9V batteries 05/27/2010
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.
Circuit may save property and life 05/13/2010
Supervise and power-sequence an SOC 05/13/2010
Bicolor LED driver uses two leads 05/13/2010
Pulse generator with precision output-duty cycle operates at a repetition rate beyond 50 MHz 05/13/2010
Tables ease microcontroller programming 04/22/2010
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 MSP430ís 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.
Battery simulator has variable ESR response 03/18/2010
This active circuit represents many battery types.
Use two ICs to produce both waveforms.
Strategy processes video in RAM 03/18/2010
How you process images in RAM can eliminate problems with different image sizes.
Control stepper motors in both directions 03/18/2010
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.
Add hysteresis to a voltage comparator 03/ 4/2010
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.
Broken-coil detector is simple yet robust 03/ 4/2010
An oscillator, filters, and comparators detect missing wires in an assembly line.
Generate magnetic fields with a microcontroller instead of mechanical parts.
Timers debounce switches and let you decide when lapses have expired.
Tilt/fall detector has staggered thresholds 02/18/2010
Comparators and a voltage-divider network let you set threshold levels.
Voltage reference stabilizes current sink 02/18/2010
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.
Drive 12 LEDs with one I/O line 02/ 4/2010
Use a binary counter to generate LED-lighting codes.
Circuit precludes common-mode conduction 02/ 4/2010
A crossover-control circuit prevents two or more transistors from powering on at once.
Use behavioral models to simulate circuit elements.
Drive a power MOSFET to 100V dc with this signal-conditioning circuit.
Two Schottky barrier diodes clamp error voltages, cut output glitches.
Excel spreadsheet measures analog voltages 01/21/2010
Turn an unused parallel port into a data port.
Algorithm keeps data safe 01/21/2010
Prevent data loss against power blackouts and other interruptions.
LED flasher checks fiber-optic strands 01/ 7/2010
Send visible light through strands to check for breaks.
Get the right amount of gain for your op-amp application.