These circuits are 'First In' type alarms circuit. The first photosensor covered will give an output and disable the other sensor.
The circuits are designed to be used to score Cub Car races but could be used for other events that are completed in a narrow time window.
The next circuit will score 4 lanes and has automatic reset. The schematic shows four lanes but two, three of two sets of two lanes could be scored.
The variable 500K resistors shown in the first two circuits could be replaced by a fixed 470K resistor.
A circuit board that can be used for this circuit is on this 4 Photo-Detector With Delayed Release And Bipolar Output page.
The explanations for the circuits on these pages cannot hope to cover every situation on every layout. For this reason be prepared to do some experimenting to get the results you want. This is especially true of circuits such as the "Across Track Infrared Detection" circuits and any other circuit that relies on other than direct electronic inputs, such as switches.
If you use any of these circuit ideas, ask your parts supplier for a copy of the manufacturers data sheets for any components that you have not used before. These sheets contain a wealth of data and circuit design information that no electronic or print article could approach and will save time and perhaps damage to the components themselves. These data sheets can often be found on the web site of the device manufacturers.
Although the circuits are functional the pages are not meant to be full descriptions of each circuit but rather as guides for adapting them for use by others. If you have any questions or comments please send them to the email address on the Circuit Index page.
05 April, 2012