Scratch seismometer

Homemade Seismometer

Seismometer with Accelerometer

Accelerometer

This page shows you how to program a seismometer using Scratch with a simple Python script. I advise you use a Raspberry Pi and a PC, as some of the scratch projects run very slowly on a Raspberry Pi.

Instructions

  1. Once your Raspberry Pi is running with the ADC plugged in, and connected to Wi-Fi (note if you are at school, this may be blocked, in which case you may need to use a mobile phone to connect to a personal hotspot).
  2. Next download the Python script, which is also on the Github page. And if you will use the accelerometer also download the two 'adxl345...' files into the same folder. To use the accelerometer you will need to make a I2C connection, just like for the ADC in the first page, except for the positive power, what was Vdd, connect it to 3V3, not VIN, as that is for 5V.
  3. Next open Scratch on your computer, connected to the same Wi-Fi. Then go to the 'sensing' tab and place the sensor value block. Then right-click on this block and select 'enable remote sensor connections'. This allows communication between Scratch and the Raspberry Pi script.
  4. Type 'cmd' into the start menu, a command line will open. Type 'ipconfig' into it, and look for a line starting with 'IP address', and write down the number that follows.
    Now, on the Raspberry Pi type the following command in the terminal: 'ls /dev/' Look for a file named ttyACM0, where 0 could be any number, and if it is not 0, then write this down.
  5. If you want to only use either the ADC or the accelerometer, comment out in the python the lines corresponding to either sensor. Run the python script 'scratch.py' you downloaded earlier, and enter the IP address.
    NB if you want to run scratch on the Raspberry Pi, enter 'localhost' here. Then enter the ADC location (typing nothing sets it as the default ttyACM0).
  6. Now you can either make your own Scratch programs using the sensor values, or run the ones in the download, and alter and improve them as you like.

Making a simple 'seismometer'

Raspberry Pi and a coil

You can make a simple 'seismometer' if you make a coil by wrapping wire around a small tube or use a pre-made one as in the photo. Position a ruler with a magnet above it fixed between two books. The paperweight below is just to get it to the right height.

Then connect the coil to the analogue to digital converter (ADC) and to your Raspberry Pi and PC.

Raspberry Pi and an accelerometer

Using an accelerometer as your sensor, you can attach it to the end of a pole, with the pole hanging from a retort stand. Use a spring, as a hinge, to join the clamp stand to the pole. This allows some vertical and side-to-side movement.

Then connect the accelerometer directly to your Raspberry Pi and PC.