EDN design ideas 2011
January 2011
Reliable 555 timer doesn’t falsely trigger 01/ 6/2011
Test continuity with an LED
Flash an LED from ac-mains power
Transistors drive LEDs to light the path
Use an optocoupler to make a simple low-dropout regulator
Power an LED driver using off-the-shelf components 01/20/2011
Oscillator has voltage-controlled duty cycle
Generate noisy sine waves with a sound card
Decode a quadrature encoder in software
February 2011
Compute a histogram in an FPGA with one clock 02/ 3/2011
Control an LM317T with a PWM signal
High-speed buffer comprises discrete transistors
Limit inrush current in high-power applications
Protect MOSFETs in heavy-duty inductive switched-mode circuits
Reduce acoustic noise from capacitors 02/17/2011
Function generator has varibale frequency
Power supply accepts wide input-voltage range
Circuit lets you test capacitors
March 2011
Design provides single-port-to-dual-port SDRAM converter 03/ 3/2011
Zener diode protects FPGA inputs
Bicolor LED indicates 10 states
Relay driver switches two relays with one pin
Anticipator circuit speeds signal settling to a final value 03/17/2011
Schmitt trigger provides toggle function
Active multiplexing saves inputs
Finely tune the hue of blue-light sources
April 2011
Low-component-count logic probe works with TTL and CMOS logic 04/ 7/2011
Circuit implements photovoltaic-module simulator
Switch circuit controls lights
Isolated PWM suits low frequencies
Increase efficiency in embedded digital-I/O lines 04/21/2011
Modulating a reference allows maximum-value search for phase detection
Offline supply drives LEDs
Light an LED without wasting energy
May 2011
Circuit secures bootstrap operation under light load 05/12/2011
Build an accurate bipolar voltage reference
Send MIDI signals over long distances
MOSFET provides high power at low loss
Waveform generator minimizes amplitude dependency 05/26/2011
Produce current from positive or negative high-voltage supplies
Arrange LEDs as seven-segment displays
Logic gates form high-impedance voltmeter
Measure resistance and temperature with a sound card
June 2011
Potentiometer calibrates photodiode amplifier 06/ 9/2011
Drive 16 LEDs with one I/O line
Circuit measures battery capacity
Programmable driver targets piezoelectric actuators
Circuit boosts voltage to piezoelectric transducers
Protect power-LED strings from overcurrent 06/23/2011
Simple flasher operates off ac mains
Use resistor noise to characterize a low-noise amplifier
Build a UWB pulse generator on an FPGA
Generate swept sine/cosine waveforms with two filters
July 2011
Compensate for four-wire sensor errors 07/14/2011
LED-current limiter accepts ac or dc
Voltage inverter employs PWM
Form positive pulses from negative pulses
Positive edges trigger parabolic timebase generator 07/28/2011
Measure small currents without adding resistive insertion loss
Power resistor varies in value
Minimize noise in power-supply measurements
August 2011
Driver circuit lights architectural and interior LEDs 08/11/2011
Use op amps to make automatic-ORing power selector
Charging time indicates capacitor value
Circuit provides universal ac-input-voltage adapter 08/25/2011
Logic probe uses two comparators
DAC fine-tunes reference output
LEDs indicate sound level
September 2011
Polynomial rotation accelerates CRC calculations 09/ 8/2011
Simple circuit measures optocoupler's response time
Circuit provides visual verification of IR pulses
An LED's intrinsic capacitance works in a 650-mV LRC circuit
Eight LEDs make a 100-division voltmeter 09/22/2011
Simple circuit controls the rate of voltage change across a capacitor or another load
LED bar-graph display represents two digits
October 2011
Circuit controls inrush current in ac-operated power supplies 10/ 6/2011
Save 3 dB of output power using feedback to set the output impedance
Optically isolated overcurrent detector works from ac mains
Simple circuit helps to protect a vehicle-reverse camera
Use a self-powered op amp to create a low-leakage rectifier 10/20/2011
Simple reverse-polarity-protection circuit has no voltage drop
Series-LC-tank VCO breaks tuning-range records
November 2011
Circuit detects rapidly falling signals and rejects noise 11/ 3/2011
Hack into a stopwatch to make a phototimer
Comparator directly controls power-MOSFET gate
AGC circuit uses an analog multiplier
Add extra output to a boost converter 11/17/2011
Fabricate a high-resolution sensor-to-USB interface
Converters yield droop-free S/H circuit
December 2011
Inexpensive VFC features good linearity and dynamic range 12/ 1/2011
Mains-driven zero-crossing detector uses only a few high-voltage parts
Build an op amp with three discrete transistors
A diode ladder multiplies voltage under software control
Charger extends lead-acid-battery life
Circuit provides more accurate multiplication 12/15/2011
A few added components make a self-contained controller for 100A load
Simple night-light uses a photoresistor to detect dusk
Simple tester checks Christmas-tree lights