Geophone Dual Axis Sensor with Amplifier Vibration Detector

Description

This is a dual axis geophone, which senses vertical and horizonal movement, I built an amplifier with a variable brightness 10 led display indicating relative movement/vibration. It includes a beeper that follows a user selected led and a relay which also follows a selected led but the relay has a minimum 1/2 second output.
Really sensitive, at high sensitivity it will detect a dime falling on carpet 10' away. However, at high sensitivity it also detects nearby traffic, hvac, motors, and especially wind. Wind moves structures and the geophone detects that motion. Drove me nuts during initial testing, I didn't make the association.
What seems to work best is to set the sensitivity so the first two leds flicker with background "noise" and set the beeper and relay to the fourth or higher led.
While placement of the geophone matters, it seems to work well on any surface. Wood, concrete, even carpet. It must be within 30 degrees of vertical, the cord at the top.
It detects normal footsteps at 30' or more on wood or concrete, maybe 15' on earth, but that will vary a lot, depending on soil type. Slow movement isn't detected, though it's difficult to move undetected within 5'. Try standing on one leg, see how steady you are.
The geophone has a 12' cable with a 3.5mm stereo plug. You can use an extension, but keep in mind the longer the cable the more 60Hz it will pick up, effectively lowering sensitivity. It's encased in pvc, should be good for outdoor use. If buried you need to protect the cable. If you don't want the pvc case send me a message. The amplifier is not weather resistant. Keep it dry.
It runs on a name brand 3000mah Li-ion 18650 battery which will power it for days with light use. Lots of activity with leds at high brightness and relay use will decrease that to hours. It draws about 30 ma with no activity, up to 500 ma at maximum. A 5V power supply/charger is included.
On the rear panel;
Matrix to select beeper and relay leds.
1.3mm x 3.5mm power jack for a 5V supply, pin - (pin + can be selected internally).
3.5mm stereo jack for geophone.
Volume adjust for internal beeper.
20 turn gain control that adjusts gain about + or - 50%. CW increases gain. Use only if you can't adjust the          front sensitivity so the first 2 leds flicker.
Small screwdriver for adjusting gain, beeper volume.
Removable terminal block;
1 +12V @.2A output.
2 Relay contact common.
3 Relay contact normally open.
4 External beeper +
5 Ground
6 Amplifier out. For an oscilloscope or other analyzer. 100K impedance, 0-2.5VAC. About 6-200 Hz, mostly
below 40 Hz. AC coupled, you can internally select DC coupled with a 2.5V reference.
Schematic included.