A routine requirement in experiments on synchrotron light sources is the measurement of the currents generated by photoemission. Accurate recording of such low level signals is often problematic due to electronically noisy environments and the distance between the data acquisition computer and the experiment. We present the design of a low current amplifier whose small size enables it to be mounted directly onto the experimental chamber. The device generates a frequency output proportional to its input signal. This method of frequency transmission ensures a high level of noise immunity and permits the use of standard counting electronics. Multiple devices may be driven from a common clock, derived from the counter clock, thus eliminating errors due to clock frequency drift.

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