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erellaz / seisberry

Code for Raspberry Pi seismograph, 3 components
MIT License
8 stars 3 forks source link

A couple of questions as I build this with my daughter #5

Open astrotater opened 1 week ago

astrotater commented 1 week ago

My daughter was learning about earthquakes and seismographs in school, which inspired me to build this with her. I have never worked with a geophone before. You mention a 395-ohm geophone resistor with a 1000-ohm shunt. Could you explain that in a little more detail? I have 2 horizontal and 1 vertical 10Hz GD-10J geophones I ordered off Aliexpress. Now that I have them, I'm not sure what to do next in regards to the resistor and shunt before I hook them up to the A/D board.

I attached a photo of how the geophone is supplied from Aliexpress.

IMG_6318

erellaz commented 1 week ago

Resistor is optional, to change the resonance frequency or sensitivity of the phone. The manufacturer provides curves with the frequency in x and the sensitivity of the phone in y. Usually you have a couple of curves, one in "open circuit", ie no resitor, and a few with various resistors. The resistor is the shunt. You do not want to connect the 2 pads of the phone together. Here is how it should look once the shunt resistor is installed: image

erellaz commented 1 week ago

And here is an example of response, without the resistor (red curve) and with a resistor (green curve). image

erellaz commented 1 week ago

Then, whether or not you use a resistor, connect a wire to each pad, and connect them to the ADC board..