  A light emitting diode (LED) pulser has been developed that can be used for
tests or calibration of timing and amplitude sensitivity of particle physics
detectors. A comparative study is performed on the components and pulser output
characteristics before and after application of 800 MeV protons and cobalt-60
gammas. This device is demonstrated to be tolerant to fluences up to 6.7
$\times$ 10$^{13}$ 800-MeV-p/cm2 and gamma doses up to 5 Mrad.
