Manufacturer of electronic instrumentation including signal conditioners, custom power supplies, computer controlled amplifiers and computer controlled signal conditioning instrumentation.




The Model 665 is a combination computer-controlled static/dynamic strain gage amplifier module.  Features include an adjustable gain, zero, external cal, filter, excitation and excitation monitor.  Each channel has its own isolated constant current excitation source.


Amplifier channels: Channel A is AC or DC coupled with variable gain and filter
Channel B is DC coupled with two gains and fixed filter
Channel A gain settings: Fixed log steps 1, 2, 5,10, 20, 50, 100, 200, 500, 1000, 2000, 5000
Channel B gain settings: 1 or 100
Gain accuracy: ±1%
AC/DC coupling: Selectable on Channel A only
DC offset: Rack control performs auto-zero at each gain or filter change; programmable offset from -100mVDC to +100mVDC; offset affects Channel A if DC coupled, else Channel B
Frequency response: AC channel: Six-pole Butterworth lowpass, selectable at 5kHz, 20kHz, 40kHz or bypassed; 5Hz highpass, single pole
DC channel: Four-pole Butterworth lowpass at 11Hz
Bridge mode: ¼ bridge, ¼ bridge three-wire, ½ bridge, or full bridge  with 120? and 350? internal completion resistors; EMF mode disconnects completion, balance, and excitation
Excitation: Excitation source isolated from amplifier output common; constant voltage, programmable from 1.0-15.0VDC; up to 100mA available; short-circuit current limited to under 40mA
Bridge balance: Autobalance cycle initiated from control webpage; dual 12-bit DACs apply balancing current to +S leg of bridge; balances on channel A if DC coupled, else channel B
Fault indication: One green LED per channel turns red if amplifier exceeds ±10V; both LEDs turn red if bridge autobalance cannot be completed
Offset: Less than 3mVDC at output
Shunt calibration: One of four precision cal resistors applied from -P to –S
11.88k, 19.88k, 49.00k, 99.00k
Noise: Less than 5µ VRMS RTI, filter in, input disconnected
Memory: On-board EEProm stores serial number, calibration date, etc.
Mechanical: 5.5” x 13.5” board, use with Model 5020-102 rack