µ[micro]electronics info

A weblog focused on interesting circuits, ideas, schematics and other information about microelectronics and microcontrollers.




Because I have not tested all electronic circuits mentioned on this pages, I cannot attest to their accuracy; therefore, I do not provide a warranty of any kind and cannot be held responsible in any manner.

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Measuring Heart Rate

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 superbright red LED. The finger penetrating light was detected by a light-frequency converter TSL230. The period of the signal from the TSL230 was using the capture of the micro-controller unit with an accuracy of about 15-bit. Signals were suppressed through digital filtering and the pulse signal was extracted.

Pulse measurement in reflection

For the lighting of the skin's surface, an infrared LED was used. The sensor use PIN photodiode. Ambient light and high frequency interference signals were eliminated with an analog circuit filters.

Optische Messung der Herzfrequenz (German)

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