We kick off June with an excerpt from Syuzi Pakhchyan’s excellent resource for wearable tech, Fashioning Technology. Want to learn more about LEDs and diodes? We’ll be covering them all this month.
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Scott Harden’s DIY electrocardiogram (ECG) uses a LED shining light through his finger into a photo transistor, with the resulting signal amplified with a LM324 quad op amp. The goal of this project is to generate an extremely cheap, functional ECG machine made from common parts, most of which can be found around your house. […]
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On Make: Projects, Jason Poel Smith uses a pair of LM741 op amps to build an self-dimming night light that turns itself off after a period of time so you don’t waste electricity. The timer is made from a 741 op amp (operational amplifier) wired as a comparator. It compares the voltage across a capacitor […]
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Robot Room’s David Cook shows how an LED and op amp, along with a resistor and cap, can be built into an amplified color sensor. Unfortunately, even under the best conditions, photodiodes (and reversed LEDs) don’t provide a lot of current flow. The output of the photodiode needs to be amplified for the light-detection signal […]
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Instructables user laserjocky built this function generator for a term project in school. It’s capable of producing a square, triangle, and approximate sine wave up to a frequency of around 300kHz. Op-amps are designed with negative feedback in mind and are typically slower, but they can be used for making voltage comparisons. I chose to […]
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Instructables user diy_bloke built this op-amp controlled pump for his garden, using the classic 741 operational amplifier. He wrote a very detailed how-to including showing how to etch a PCB, as well as how to make a humidity sensor out of gypsum: The simplest form of a soil humidity sensor is made from two galvanized […]
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Each month this year, we’re exploring a different electronic component, delving into what it is, how it works, and how you use it in projects. Last month we covered resistors, and before that we looked at batteries. This month we examine operational amplifiers, often called op amps. An op amp is an electronic component used […]
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