Because a Photo-Detector
Produces a current proportional to it's incident light, it is necessary
to convert that current to a usable voltage. Since our nominal currents
will range from -50pA to -50uA, a gain is added as well.
low currents are 'sensed' from the photo-detector, it is necessary to
stray noises to a minimum. A molded aluminum housing was used to
additional shielding and handling capability. It is approximately 1" x
3" with the following external connections: IN, OUT, NULL, +/- NULL
+Vcc, -Vee. Gain of the trans-impedance amp is 200,000, giving an
voltage range of 10uV to 10V.
- Specifications for the MAX420 op-amp can be seen at MAXIM.
- The following is the completed schematic:
- Below is a plot of I-V converter performance for the Units #1 and #2, denoted V1 and V2:
This page/project based on previous work from John Becker.
Last Modified September 28, 1999.
© Rob Point 1999
All rights are reserved. Reproduction in whole or in part is prohibited without the written consent of the copyright owner. for more information contact Rob Point