There are zillions of LED chaser circuits and most of them use 1 integrated circuit for the sequence (e.g. CD4017) and another for the clock (e.g. 555). Some go even further and use a microcontroller (overkill). This simple circuit uses only a CD4060 cmos I.C. for both functions. and can drive up to 800mA worth of LEDs (around 35 in parallel) for each of the 3 channels. CD4060 is a ripple binary counter and does not have decoded outputs as the CD4017, but we can easily decode decimal 0 with diodes (DTL diode-transistor logic gates). Decimal 1 and 2 are taken directly from the 2 least significant digits (LSD). We will also decode decimal 3 to reset the counter back to 0.
Circuit Diagram & Details- IC1: CD4060 cmos 14 stage ripple binary counter plus oscillator
- Q1: BC327 PNP transistor (800mA)
- Q2-Q3: BC337 NPN transistor (800mA)
- D1-D4: 1N4148 diodes
- R1-R3: 100ohm for 5 parallel LEDs. (recalculate for more parallel LEDs) - Even more LEDs with higher voltage supply voltage (parallel-series connected LEDs).
CD4060 Decoding of 0 - 1 - 2 - 3 (truth table):
CD4060 - Ripple Binary Counter & Oscillator:
Decoding of Binary 00 (Decimal 0):
Decimal 1 and 2 , Directly From Binary Digits 0 and 1:
Decoding of Decimal 3 From Binary (11) - Resets Counter to 0:
R5 and C1 Determine Clock Frequency (chaser Speed):
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