711 Leading Edge Discriminator



The Model 711 is a high-performance, six channel, leading edge discriminator packaged in a single width NIM module. It features independent threshold and width controls, updating or burst guard operation, a fast veto for inhibiting, a prompt linear summed output, and a versatile output configuration with five outputs per channel.

The 711 has high input sensitivity of -10mV variable to -1Volt via a 15-turn front panel control. A front panel test point on each channel provides a DC voltage equal to ten times the actual threshold to insure accurate settings.

A two position switch permits the 711 to be used as either a conventional updating discriminator or, when in the Burst Guard position, an updating discriminator with the time-over-threshold feature. As an updating discriminator the output width is variable from 4nSec to 1mSec via a front panel screwdriver adjustment. Should inputs occur at time intervals less than the double-pulse resolution (typically 6nSec), the unit will not respond. In the Burst Guard mode when inputs occur that are less than the discriminator resolving time, the output will be extended until the trailing edge of the last pulse within the burst.

Inhibiting of the discriminator can be accomplished in two ways. A front panel LEMO input accepts a NIM level pulse for fast simultaneous inhibiting of all six channels. Secondly, a slow bin gate via the rear panel connector inhibits the module and is enabled or disabled from a rear panel slide switch.

A unique summed output common to all six channels delivers -1mA of current for each activated channel, thus allowing a fast decision to be made on the number of channels simultaneously hit. Up to 18 channels can be "OR'D" directly by cable to other summed outputs providing a versatile scheme to form a trigger.

The 711 has five high-impedance current switching outputs per channel. They are configured as two pairs of double-amplitude bridged outputs and one complemented NIM output. When only one output from a bridged pair is used, a double-amplitude NIM pulse (-32mA) is generated for driving long cables. Two normal NIM levels are produced when both of the bridged pairs operate into 50 ohm loads. The output risetimes and falltimes are typically 1nSec, and their shapes are virtually unaffected by the loading conditions of the other outputs.

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