|
With 12 volt power switch ON, high beam headlights on vehicle come ON. As on coming lights approach, circuit relay goes to low beams until cars pass then goes back on high beam. Power switch should be mounted on dash, and of course, parts and wiring for automotive headlamps of proper ratings. Daylight hours keep power switch OFF.
The added 5 volt battery and switch is to simulate on coming car light that would strike photocell represented by NPN transistor at upper left. Select photocell that can switch 2N3906 transistor on, I do not have part number.
How to set system: power off, set all variable resistor to maximum resistance. Now short 2N3906 PNP transistor collector to emitter and turn power switch on with light sensor covered. Adjust horizontal 5 k variable resistor ( the horizontal one closest to power switch) until first upper left relay trips and slightly more. Next, remove short on 3906, adjust other two 5 K ohm variable resistors for zero bias on base of 2N3906 with no light on photo resistor. Now, cover photo cell and adjust first horizontal variable resistor closest to power switch to firmly trip when proper amount of light is present. Remove photo cell cover and fine tune for driving conditions.
|
