Projects with Ryan Slaugh: Active Filters & Tool Suggestions


Over the last few videos I have highlighted helpful circuits. In this video, I highlight an active filter setup utilizing an operational amplifier. Filters are very helpful when working with analog signals.  Often the range of frequencies needed are not across the entire band, therefore you need to filter out... Read more »

Projects with Ryan Slaugh: Simple Amplifier

Screen Shot 2014-01-08 at 3.48.56 PM

Building upon my last video, I’ve decided to make a simple circuit using some op-amps.  One is the general op-amp LM741. The other is a specific op-amp, LM386, that is designed for audio amplification. This circuit can be used to amplify microphones or be used as a circuit sniffer depending... Read more »

Visualize Your Heartbeat With This Homemade Pulse Sensor


Infrared Pulse Sensor is the latest addition to our beginner-friendly series of Weekend Projects. Inspired by a photoresistor pulse sensor, MAKE's Technical Editor Sean Michael Ragan built this IR-based pulse sensor using emitter and detector diodes, combined with an LM384 op-amp IC and an Arduino. Read more »

Infrared Pulse Sensor


Taking your pulse is as simple as holding a finger to your neck or wrist and timing the beats with your watch. But if you want to record the data or use it to trigger events, you need to turn that mechanical pulsing action into an electrical signal. This pulse... Read more »

Make a Heartbeat Detector With an Op Amp


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... Read more »

Use an Op Amp to Make a Self-Dimming Night Light


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... Read more »