Day 16: Seismograph
seismograph seems to be working well apart from the fact that the pendulum
can easily fall off the base, especially if the base is slightly off from
the flat. We put the device onto the bridge and it seems to log the cars
quite well. Unfortunately the bridge tends to move a lot vertically but
there is little horizontal movement which is really where our seismograph
has greatest sensitivity!! - it shows the Rough Science principles though.
build an electronic addition which consists of a magnet attached to the
weight and a coil of wire mounted below it on the base. The wire ends
from the coil go to a simple 1-transistor amp and this boosts the signal
so that the output is easy to see on a meter. Even quite small motions
can be detected by this modification. Because the coil and magnet records
the change of movement then this device make the position sensitive seismograph
(distance) into a motion (velocity) detector. Steve Evanson asked me if
we can drop the electronics however as they think it would be too complex
(“a mystery”) to explain on TV.