This simple transistorized running light circuit can be used to produce sequential LED light chasing effect without using an IC.
The drawing underneath represents a multistage light chaser utilizing just 3 BJTs and other passive parts and no coordinated circuits.
The thought is to interface the lights so that as one turns off it causes the by turn on, etc.
How the Circuit Functions
This is implemented with a subsequent capacitors between every stage that charges when a stage turns off and supplies base current to the following transistor, subsequently turning it on.
Any number of stages can be utilized and the drawing underneath shows 3 little christmas lights running at around 5 volts and 200mA.
The circuit may need to be physically begun when force is connected.
To begin it, unite a passing short over any of the capacitors and afterward evacuate the short. You could utilize a manual push catch to do this.
Point by point operation:
Assume this simple transistor running light circuit doesn't switch ON when supply is connected and all lights are off, and every one of the three capacitors are charged to around 5 volts.
We join a jumper over the 220uF capacitor on the left which releases the capacitor and turns on the 2nd stage transistor and comparing light.
At the point when the jumper is removed, the capacitor will begin charging through the base of the stage 2 transistor and stage 1 light.
This causes the stage 2 transistor to stay on while the capacitor keeps on charging.
In the meantime, the capacitor joining stage 2 and 3 will release through the 100 ohm resistor and diode and stage 2 transistor.
At the point when the capacitor charging current falls underneath what is expected to keep stage 2 turned on, the transistor and light will kill bringing on the voltage at the collector of the stage 2 transistor to ascend to 5 volts.
Since the capacitor associating stage 2 and 3 has released and the voltage ascends at the collector of stage 2, the capacitor from stage 2 and 3 will charge bringing on the 3rd stage to turn on and the cycle rehashes for progressive stages 4,5,6,7.... furthermore, back to 1.
The arrangement rate is controlled by the capacitor and resistor values (220 uF and 100 ohms for this situation), load current (200 mA for this situation), and current increase of the specific transistor utilized.
This LEDs keeps running at around 120 complete cycles for each moment for 3 lights, or around 167 mS.