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The last time you were in the emergency room after a horrible accident involving a PVC pressure vessel, a nurse probably clipped a device called a pulse oximeter onto one of your remaining fingers. These small electronic devices detect both your pulse and blood oxygen level with a pair of LEDs and a photosensor. [Anders] sent in a great tutorial for building your own pulse oximeter using a fancy … [Read more...]
The next time you're unfortunate enough to make your way to a hospital, emergency room, or urgent care clinic, you'll be asked to attach a small pulse monitor to your finger. The device the nurses clip on to one of your remaining digits is called a photoplethysmographic sensor, and basically it is able to read your pulse through reflected light. In the search to find out how these devices … [Read more...]
After seeing some heart rate monitor apps for Android which use the camera and flashlight features of the phones, [Tyson] took on the challenge of coding this for himself. But he's not using a smart phone, instead he grabbed a headlamp and webcam for his heat rate monitor. To start out he recorded a test video with his smart phone to see what it looks like to cover both the flash LED and … [Read more...]
[Shane Burrell] decided to spend some time learning how the keypad on the his Kenwood TM-710A APRS radio mic works. It uses a different technique than you might think. Normally a grid of buttons is scanned as a matrix to detect keypresses, but this hardware actually counts pulses on a serial wire to take each reading. The stock radio sends a steady digital pulse to the handset and with each … [Read more...]
At roughly $20 to build, this 9 digit pulse counter is an excellent example of home built tools. The builder, [Josh] found himself repairing a device and in need of a pulse counter. With the components cheaply available, he just built his own. He says that it has a few limitations, like display brightness, but overall it seems to do the job well. You can download the PCB from his site. [via … [Read more...]
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