This package includes the parts to build a Schmitt trigger photogate (either SPG1 or SPG2) and an electronic delay unit.  There is a $1.00 discount from the price of both kits purchased separately. There is an additional $1.00 discount for purchasing the combination with a breadboard.

When built on a breadboard, the completed circuit will look similar to that shown. Click on the photo for a larger view.

For descriptions of the photogate and delay unit kits, go to these links: 

SPG photogate kits                DU electronic delay kit

*Customers have reported that when using the delay unit outputs to trigger Canon 430ex and 580ex flash units, the flash unit is disabled after each discharge until the unit is turned off and on again. In order to correct this problem, two 1-kW replacement resistors are included with each delay unit and combination kit. These resistors may be used in place of the 22-kW resistors that lead from outputs 5 and 9 of the 556 timer.