Fig. 7

Preamplifier design a regulators to drop +18 V to 15 V. b Zener diodes used to drop 15 V to 3.3 V, which provides the reference voltage for voltage clipping circuit. c Voltage-to-current converter interfaced with a computer-controlled reed relay switching hardware. The current source signal could be routed to any of the up to 96 channels. d Voltage protection/clipping circuit. e Instrumentation amplifier, amplification, and filtration stages