Did you know that The human heart can be measured optically. The heart beat with the varying blood pressure leads to a measurable change in the visual content of peripheral blood vessels. This is as good at the finger detect. There are two project work available, which were so far advanced that the optical signal pulse seized on a liquid crystal display graphically. Both works have been with a microcontroller PIC16C74 to collect and visualization of the signals.
Pulse measurement in a light
The light source was a red LED superhelle. The finger penetrating light was a light-frequency converter TSL230 detected. The period of the signal from the TSL230 was using the capture of the micro-controller unit with an accuracy of about 15-bit recorded. Through digital filtering 50Hz interfering signals were suppressed and the pulse signal extracted.
Pulse measurement in reflection
For the lighting of the skin's surface, an infrared LED used. the censor use PIN photodiode. With an analog circuit filters were equal light and high frequency interference signals eliminated. The signal was pulse by the A / D converter of the microcontroller with 8-bit digitized.
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