Simple VU-meter circuit

VU-meter circuit built on a breadboard using transistors, diodes, resistors, and LEDs @ Build Electronic Circuits: It’s basically a simple display for showing a value. It’s originally for showing signal level in audio circuits, but there’s no reason you can’t use it to show temperature, rain intensity, light level, or whatever other value you are […]

Push button toggle switch, old style

Bertho of Vagrearg writes: I recently answered a question about how a specific circuit worked and I was so intrigued that I just needed to write down my findings and share it. The circuit uses a single (cheap) push-button to make the output toggle with debouncing and no-delay switching. The circuit used originally two NOR-gates and […]

Simple circuit to turn your oscilloscope into a TDR

Simple circuit to turn your oscilloscope into a TDR: This simple circuit allows you to use your oscilloscope as a Time Domain Reflectometer (TDR). This is how it works. Send a pulse down a cable and watch for the reflection. Most people think a TDR is more complicated than this. Your oscilloscope is used to […]

App note: Current sense circuit collection

Here’s a current sense circuit collection from Linear Technology. The collection is organized by application type and for each one there are a few example circuits. High side, low side, level shifting, high and low voltage, fault sensing, etc: Sensing and/or controlling current flow is a fundamental requirement in many electronics systems, and the techniques […]

Digitally adjustable precision reference driven via PWM

This simple circuit that converts a 5V PWM signal into a variable precision reference voltage with a rang of -2.5V to +2.5V.  Many designs, like a digitally controlled power supply, programmable dummy load, etc, require a Digital to Analog Converter to supply a stable reference votlage. This circuit is cheaper and requires less pins from […]

App note: Overvoltage protection for amplifier outputs

rsdio writes:   this circuit includes one of my favorites: a dual, common-cathode diode package To protect audio amplifiers and other automotive electronic circuits in the event of an accidental direct connection to the car battery voltage, add the circuitry shown (a shunt regulator, diodes, and an n-channel MOSFET in series with each audio path).

App note: Automotive power circuit handles interruptions and 72volt spikes

rsdio writes:  More good ideas to steal and repurpose This circuit maintains power to the load regardless of momentary shorts or opens in the supply voltage, and includes a low-current overvoltage-protection IC (MAX6495) that protects the load against transient voltages up to 72V.

App note: Low-cost circuit converts clock to low-distortion sinewave

rsdio writes:  nothing beats a pure sine wave oscillator, except another pure sine wave oscillator at a similar frequency: This circuit derives a pure sinewave from a crystal-controlled clock source by using a ring counter to remove the highest-amplitude unwanted harmonics, and filtering the result with an 8th-order lowpass, switched-capacitor elliptic filter (MAX7400).

Jameco Puzzler: a non-electronic voice transmitter?

The legendary Forrest M. Mims, III, created the above puzzler for Jameco. If the radio DJ performing a show while perched on the construction boom drops his cellphone, how can be proceed with his radio show if he is prohibited from touching the ground? Visit the Jameco site for more details, hints and the solution […]

App note: Monitor negative power supplies

Precision circuit monitors  negative-supply threshold: Using an IC (MAX971) that includes an open-drain comparator and a precision 1% voltage reference, this circuit monitors the magnitude of a negative supply voltage and provides a digital warning of fault conditions. To monitor multiple negative voltages, use the MAX974, which includes four comparators. Thanks for the tip rsdio!

Simple current limiter is programmable

rsdio tipped us to an app note on a simple current limiter. This circuit lets you program a current limit without using microcontrollers or data converters. It consists of a charge-pump voltage doubler (U1), a current-sense amplifier (U2), and two n-channel MOSFETs. The sense-resistor value determines the maximum current limit. Thanks rsdio!