Circuit delivers constant power to a load

If you have a load with a variable or poorly specified resistance and want to regulate the power applied to it (a heater for example), merely controlling the voltage or current will not work, as in both cases the power P = I2R = V2/R depends on R. Instead, let us generate pulses with constant energy Epulse, independent of the resistance of the load RL. Then by changing the frequency f of the pulses we can c ...

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Inverter crystal oscillator

In numerous RF synthesizer chips lies an inverter with input and output pins for making a reference crystal oscillator clock. I built some discrete chip inverter xtal oscillators with 74HC series logic gates to better examine them. You'll quickly recognize the oft-used Pierce oscillator topology with 1 trimmer capacitor to tweak the fundamental frequency which might vary from factors like crystal aging and ...

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Reverse engineering the popular 555 timer chip (CMOS version)

Reverse engineering the popular 555 timer chip (CMOS version) This article explains how the LMC555 timer chip works, from the tiny transistors and resistors on the silicon chip, to the functional units such as comparators and current mirrors that make it work. The popular 555 timer integrated circuit is said to be the world's best-selling integrated circuit with billions sold since it was designed in 1970 b ...

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IoT Santa Tracker on Colorful World Map

Use MKR1000 to show the Santa location in real-time on a colorful world map made of neopixels. Story Hohoho... Santa is here! Every year the Christmas Eve Santa Claus sets out on a journey travels around the globe and sends out presents to all the children around the world. But would it be cool to know where the Santa Claus is at that day? MKR1000 Santa Tracker to the rescue! You may already know there are ...

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How To Select a Capacitor

When I was working on the capacitors section for the next version of Common Parts Library, I realized that it would be helpful to explain why one might pick one capacitor type over another. This information is important because there are a lot of factors (temperature characteristics, package, etc.) which might make a type of capacitor (electrolytic or ceramic) better than others for your project. In this bl ...

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555 Timer Teardown

If you've played around with electronic circuits, you probably know[1] the 555 timer integrated circuit, said to be the world's best-selling integrated circuit with billions sold. Designed by analog IC wizard Hans Camenzind[2] in 1970, the 555 has been called one of the greatest chips of all time with whole books devoted to 555 timer circuits. Given the popularity of the 555 timer, I thought it would be int ...

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