A potted timer and circuit board assembly for use in a regenerative desiccant air dryer. The potted timer and circuit board assembly comprise a support member of a predetermined size and shape having a first surface and a second surface. A conductive pattern of a predetermined material and thickness is disposed on at least one of the first surface and the second surface of the support member. A predetermined quantity and arrangement of electronic components of a predetermined voltage is disposed on at least one of the first surface and the second surface of the support member for providing a timed electronic signal to a solenoid valve that pneumatically operates an air dryer. A non-conductive material of a predetermined composition encases the electronic components on the support member for insulating the electronic components from environmental elements. The support member has at least one exposed member on a side of the support member for engagement with at least one receptacle on such air dryer for creating an electrical current in the potted timer and circuit board assembly. An alignment means is disposed on at least one of opposing sides of the support member for engagement with at least one slot in such air dryer for aligning and holding the potted timer and circuit board assembly in a predetermined position in such air dryer.