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 […]
Craig writes, “RF filter design is a piece of cake these days thanks to computer design and simulation tools. But actually realizing the simulated filter response in the real world can be a completely different matter! This video provides an introduction to practical RF filter design by building, testing, and tweaking a 137MHz bandpass filter […]
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 […]
Solar panel charging circuit: A special circuit is needed when charging a battery from a Solar Panel. When the solar panel is not providing any power the battery might start draining current into the panel. One common solution is to have a diode in series with the charging circuit to keep the current from going […]
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 […]
This video discusses the total noise of a non-inverting Operational Amplifier (Op Amp) circuit by Analog Devices’ Matt Duff.
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 […]
Boris shared a link to this article Embedded MP3 module: This embedded MP3 module is an universal and compact circuit (37 mm x 27 mm) for playing MP3 audio files. The MP3 module can be used in embedded systems. The MP3 files (up 65,536) are stored in a micro SDcard. Controlling the module could be […]
Rhys Jones has been working on 3D printing circuits using a RepRap printer. He has recently made enough progress to have a working circuit. One of the main problems I previously had was solubility. Running molten metals were acting as solvents for my heated nozzle – resulting in the nozzle slowly dissolving during a print. […]
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 […]
This is a simple voltage booster based on discrete components: The circuit is excellent and works down to 0.6V. It requires about 0.9V to start. I’ve got efficiencies of 80% using high gain transistors. Thanks Rohit! Via the forum.
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).
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.
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).
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 […]
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!
If you need a 5 to 10 volt DC power source and only have a couple AA batteries, here’s a simple solution from CoolCircuits. It uses four transistors and a handful of passive components to produce an adjustable 5 to 10 volt output from 1.5 to 4.5 volt input.
rsdio sends an app note: Locked-sync sine generator This circuit synchronizes a sinewave output through three decades of frequency (20Hz to 20kHz) while maintaining low THD and constant amplitude. Thanks for the tip!
In the above figure, what is the simplest way to light the LED when a ball strikes the bull’s eye? The catch: The game should not use a battery or external source of power. Check the Jameco site for the solution to this electronics puzzle.
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!