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exHomunculus

Member Since: September 14, 2011

Country: United States

  • Who said hackers couldn't fabricate?

  • Yes. I just noticed this as well. I hope you guys are around forever. This is just the kind of geeky touch that has made me a customer for life!

  • Seriously... who slept in my dog's bed?

  • I agree and apologize for any possible disinformation. You can however hook these up directly to any ADC with differential inputs.

  • I may have been a little too quick to type that.

    Since the arduino doesn't have differential inputs, you'd have to inject a voltage 1/2 of your ADC reference voltage.

    I'd like to see a schematic too. I do have a few of my own personal schematics to interface these types of sensors to ADCs. Can I give my email address on here?

  • Sure, you can hook it up directly if you want. It will work.

    What you suggest about precision op amps and an LPF is exactly how high-end seismic equipment is created.

  • It is a good quality magnet suspended by springs, surrounded by a coil. So, very similar to a microphone. Also these are similar to an accelerometer as well, just made for lower frequencies. I work with these all the time at my job.

    All you need to know is a few things to get started:

    Orientation... there are vertical and horizontal orientated versions which allow you to create a true tri-axial configuration using 3 geophones (1 vertical, 2 horizontal).

    Sensitivity. Volt/inch per sec.

    Frequency response. Most geophones are very linear from about 2-500hz. There will be a higher sensitivity in the geo's sweet spot or natural frequency. You can also use a dampening resistor to make it much more linear in response but at the cost of sensitivity.

  • I've used the LM3916 with these in the past. It's very similar to the LM3914/15. They all drive 10 LEDs which is a perfect fit. Plus, no need for a uC interface, they can be completely stand-alone.

    Hook up the RSSI PWM output from an xbee module through a low-pass filter, into one of these LM3916 and you have something pretty cool...

  • Looks as if it would be possible to solder your own wires to the 6 pads next to the connector...

  • I had the same problem and did what you said, used 0021 and it works fine now.
    Although, the original sketch worked for me. I had problems when changing the numbers sent with the SetTimeDate function. Sometimes it would output the ReadTimeDate correctly until it got to a certain time and would lock up.

No public wish lists :(