Specifications:

Number of channels:        3 max.
Gain:                      2,000 to over 12,000 - Set by a trim pot.
Frequency response:        .015Hz to 10Hz 7 pole low-pass filter.
Input/Output Connectors:   RCA jacks (stereo equipment type).
Input Impedance:           ~10K
Output:                    +- 10 volts max. Can drive around 100 feet 
                           of 75 ohm coax into a 600 ohm load at the
                           A/D card or chart recoder end.
Input Power:               24 to 28 VAC ~400MA Center Tapped Transformer.
Board Dimensions:          5 3/4 x 7 3/4 inches or 14.5 x 19.7 cm.

Description:
Each channel has a very low noise front end op-amp, 10 Hz 7 pole low-pass
filter and an output op-amp that can drive around 100 feet of coax cable. 

Cost:

$100.00 for one channel, $145.00 for two channels and $190.00 for all three 
channels. I'm selling the board built and tested without a box to keep the 
cost down. A wall mounted power supply that will work with this board costs 
$15.00.

Additional Information:

• New - Pickup Coil and Magnet for Lehman (and other) type sensors.
• Schematic (23k gif) of one channel on the Amp / Filter board.
• Schematic (11k gif) of the Power Supply on the Amp / Filter board.