Hi,
I have connected a geophone to Arduino previously using the Ole Wolf amplifier circuit and an R4 minima which works fine. I now want to make another one but had to get a different geophone. The new Geophone has a 20k resistor across the terminals which seems to be in the equivalent position as R2 in the Ole Wolf circuit. What should I do? R2 is only 1k.
The best choice of damping resistor value depends on the geophone characteristics.
I can't be sure from the product photo what value of resistance is mounted, but 20K seems unlikely.
I worked it out from a resistor code calculator either 20k or 220 ohm if those stripes are red or 1k or 110 ohm if they are brown.
But measuring across the terminals (would have taken the lower value) came out as 272 ohm. Whilst the coil resistance is stated as 375 ohm.
So thanks for your comment I will take the resistor off and measure it. If it is 1k I am all set.
Yes 1k, thanks problem solved.
