Introduction: "police" Light Flasher
How it works: the switching transistors (PNP) cant decide between each other and in doing so, it charges and discharges the caps and switches the leds on and off. resitors are for current limiting.
(originally called "two-transistor dual- led flasher.") This is a circuit that's used in RC cars, radio controlled things (if it fits), ETC.......,
it basically is a police light flasher. for some reason i had to re-do this circuit like 3 time or something, but it worked out GREAT!!!!!!!!!
This circuit will work off of a 3v or 6 v battery ONLY! 4.5 or 9.0 volts cannot be used because 9 volts changes the led "flippige", and 4.5 volts speeds it up at a really fast rate.
*NOTE*- this is not my circuit, i got it from Radioshack's electronics learning lab, i do not take any credit for this circuit.-*NOTE*
(but it was fun to build!!!!!)
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Step 1: Parts List........
2) 9015 Switching PNP Transistors ($0.75)
2) 470 OHM Resistors ($1)
2) 100 KOHMS Resistors ($1)
2) 10 uF Capacitors ($1.19)
2) Leds (of any color) ($1.59)
This circuit won't work if either of the PNP transistors are backwards
*NOTE* to change the speed of the flashing, change the capacitor values and the 2 resistor values, not the led resistors though!
Step 2: Schematic-assembaly
Here is the schematic for the flasher.
I made this on smart draw 2009, sorry for the bad quality.
Step 3: Turn Out.
the turn out was great for me but if you have problems, email me at firstname.lastname@example.org or comment.
(if anyone knows a circuit that allows you to time someone?, or a police siren! THANKS!!!!!!!!!!)