Between the period of 1969-74, I attempted to construct a seismograph. The seismograph sensor was made of 2x4 and 2x6 wood. The pendulum was made from the casing of an aluminum VW generator. I filled it with lead. The pen was linked to a five gallon smoked drum turned by a clock motor. I noted some interesting traces but do not know for sure if any of them was the result of a far-away earthquake. In those days the only way (that I knew of) was to check the newspaper to see if an earthquake had occurred.
In March of 1972 I read about how to make your own chart recorder in the Amateur Scientist column of Scientific American. I purchased several surplus seismic recording drums and attempted to adapt the largest one to my chart recorder. I made my home made pen recorder move across the drum from left to right in about five days. The drum turned at the rate of 12-inches per hour. I wound a 20,000 turn coil and attached it to the end of the VW pendulum. The coil was placed in the gap of a war surplus magnet (the one I currently use). The pen recorder would work only for a short period until one or both the HEP 245 amp chips failed and had to be replaced. In 1974 I moved from north Houston before having a chance to correct the problem. I sold the drum to a scrap dealer and have been sorry ever since. In January, 1997, I finally realized my dream of completing a for-sure working seismograph.
My 1969 seismograph sensor.
My 14 year old son, Stan, seated in front of the under construction drum recorder in 1972. He is 42 years old now.
The completed drum recorder. The home-made electronics are under the table.
The home-made drum recorder as shown in the 1972 Scientific American article.
The home-made servomotor pen recorder as illustrated in the 1972 article.