Stable pulse generator uses matched transistors in a current mirror 02/ 2/2012

Inexpensive dual transistors work as well as do legacy matched pairs.

Implement an audio-frequency tilt-equalizer filter 02/ 2/2012

Developing the transfer functions lets you customize the filter.

Circuit provides 70 dB of AGC 02/ 2/2012

A comparator autoranges to ensure that the automatic-gain-control section sees a signal between −60 and −25 dBm, keeping the FET in its linear region.

Wireless temperature monitor has data-logging capabilities 01/19/2012

You can make a wireless temps system with two ICs.

Make an asynchronous clock for VPX-based PCIe systems 01/19/2012

Careful crystal selection and an FPGA are key to success.

Use a photoelectric-FET optocoupler as a linear voltage-controlled potentiometer 01/19/2012

The circuit takes advantage of an identical photo-FET as a feedback element.

Simple circuit tests twisted-pair cables 01/19/2012

Quickly test a cable containing twisted-wire pairs and detect open or reversed pairs, shorted pairs, and shorts between unrelated pairs.

Use a boost regulator beyond its rated voltage 01/ 5/2012

Use an external FET in a common-gate cascode configuration.

Measure an amplifier's THD without external filters 01/ 5/2012

Adding a secondary amplifier boosts the THD to measurable levels.

Use air-core-coil resistance to estimate inductance 01/ 5/2012

If the coil is tightly wound you do not need the number of turns to calculate inductance.

Current monitor uses Hall sensor 01/ 5/2012

Use a Hall-effect sensor to measure dc current in the range of 0 to 40A.

Control your holiday lights with a magic wand 12/16/2011

A magnet waved past a Hall-effect sensor does the trick.

Circuit provides more accurate multiplication 12/15/2011

Convert into and out of the sampled-data domain to get an accurate multiplication.

A few added components make a self-contained controller for 100A load 12/15/2011

Add a few components and you have a stand-alone piece of test gear.

Simple night-light uses a photoresistor to detect dusk 12/15/2011

You can adjust this battery-powered circuit for different levels.

Inexpensive VFC features good linearity and dynamic range 12/ 1/2011

A voltage to frequency converter circuit builds on the work of two analog greats.

Mains-driven zero-crossing detector uses only a few high-voltage parts 12/ 1/2011

You can get isolation with low power consumption using this simple circuit.

Build an op amp with three discrete transistors 12/ 1/2011

This simple ac-coupled design inverts, runs off a single supply and is self-biasing.

A diode ladder multiplies voltage under software control 12/ 1/2011

An eight-pin micro multiplies, monitors, and delivers a boosted voltage to a load.

Charger extends lead-acid-battery life 12/ 1/2011

A circuit that properly charges sealed lead-acid batteries ensures long, trouble-free service.

Add extra output to a boost converter 11/17/2011

The added output has its own voltage regulation.

Fabricate a high-resolution sensor-to-USB interface 11/17/2011

A precision analog acquisition system fits in your pocket.

Converters yield droop-free S/H circuit 11/17/2011

Use an ADC and DAC back-to-back to process signals up to 1 kHz.

Circuit detects rapidly falling signals and rejects noise 11/ 3/2011

Combine an op-amp and a logic IC to determine signal peaks beyond a set threshold.

Hack into a stopwatch to make a phototimer 11/ 3/2011

Two transistors create a pulse train to operate a stopwatch.

Comparator directly controls power-MOSFET gate 11/ 3/2011

Circuit switching point is independent of unregulated FET voltage.

AGC circuit uses an analog multiplier 11/ 3/2011

This automatic gain control works over the audio-frequency range.

Use a self-powered op amp to create a low-leakage rectifier 10/20/2011

An amplifier that works at 0.8V is key.

Simple reverse-polarity-protection circuit has no voltage drop 10/20/2011

A relay does what semiconductors can’t do.

Series-LC-tank VCO breaks tuning-range records 10/20/2011

A series tank circuit allows you a 4-to-1 frequency range.

Circuit controls inrush current in ac-operated power supplies 10/ 6/2011

Inrush current control circuit for ac operated power supplies.

Save 3 dB of output power using feedback to set the output impedance 10/ 6/2011

You can use this with high-side or low-side output current sensing.

Optically isolated overcurrent detector works from ac mains 10/ 6/2011

The circuit uses two opto-transistors you arrange for bipolar sensing.

Simple circuit helps to protect a vehicle-reverse camera 10/ 6/2011

Add a delay to prevent short power pulses as you shift through reverse.

Eight LEDs make a 100-division voltmeter 09/22/2011

Use a counter IC to drive two sets of four LEDs.

Simple circuit controls the rate of voltage change across a capacitor or another load 09/22/2011

The output rate of change servos a pass FET.

LED bar-graph display represents two digits 09/22/2011

Novel circuit uses a reference ladder signal based on the most-significant-digit display.

Polynomial rotation accelerates CRC calculations 09/ 8/2011

This idea introduces a method of CRC calculation that rotates a polynomial instead of shifting data.

Simple circuit measures optocoupler's response time 09/ 8/2011

Measure the response speed of optocouplers in order to select matching devices.

Circuit provides visual verification of IR pulses 09/ 8/2011

Use a transimpedance amplifier to drive an LED.

An LED's intrinsic capacitance works in a 650-mV LRC circuit 09/ 8/2011

The LED and a discrete inductor form an LC tank circuit.

Circuit provides universal ac-input-voltage adapter 08/25/2011

Use a TRIAC and optocoupler to automatically change between doubler and bridge configurations.

Logic probe uses two comparators 08/25/2011

Build a logic probe whose voltage thresholds vary with your circuit's power supply voltage.

DAC fine-tunes reference output 08/25/2011

Adding a DAC and op amp makes a precision adjustable reference.

LEDs indicate sound level 08/25/2011

Build a battery-operated portable meter to measure sound-pressure levels.

Driver circuit lights architectural and interior LEDs 08/11/2011

Hold the current constant and within tolerance.

Use op amps to make automatic-ORing power selector 08/11/2011

Replace diodes with FETs to reduce power loss.

Charging time indicates capacitor value 08/11/2011

A comparator changes state when capacitor voltages are equal during rise and fall, which triggers a time measurement.

Positive edges trigger parabolic timebase generator 07/28/2011

Generate sawtooth, quadratic-parabolic, and cubic-parabolic signals.

Measure small currents without adding resistive insertion loss 07/28/2011

Floating current to voltage converter can be inserted in-line with no voltage drop and no need for a ground reference.

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