Abstract: A voltage sharing circuit which allows use of low voltage semiconductor devices to obtain higher output voltages is made up of a series stack of the low voltage devices with diode limiters provided to bias the low voltage devices such that the maximum voltage across any one of the low voltage devices is limited to a predetermined value.

Abstract: A test patch generator for electrophotographic machines automatically adjusts test patch exposure to predetermined values regardless of operator-initiated changes in exposure settings. A main illumination source exposes an original document. Integrating the main illumination source produces an electrical signal representative of the amount of such exposure. The signal is modified by a factor selected in accordance with the exposure setting, and the modified signal is used to produce a latent image test patch on a photoconductor member, the patch having an exposure value corresponding to the modified signal. Once the patch is toned, a sensor can be used to measure the patch density and any necessary adjustments to the process parameters made.