This external temperature controller allows the user to adjust the temperature of a thermoelectric cooling device or Peltier cooler through its front control panel or through a computer by connecting it to an RS-232 serial port. There are two software programs available for computer control (a full featured Windows based application and Labview modules for incorporation into other software applications). There is also a manual of the RS-232 command set for customer who need to write their own software for non-Windows based computers. This external temperature controller supports the Sciencetech PMH-04 Cooled PMT housing and others in Sciencetech's cooled sample chamber line.