The following is a simple schematic circuit diagram for an LEDs or Lamps Sequencer with a versatile modular design that allows for an unlimited number of modules to be used in a ring. This circuit can be used to sequentially light up LEDs or lamps in a ring configuration.
Circuit diagram using LEDs:
Circuit diagram using Lamps:
R1 1K5 1/4W Resistor
R2 680R 1/4W Resistor
C1 47F 25V Electrolytic Capacitor
D1 LED any type
Q1 BC337 45V 800mA NPN Transistor
P1 SPST Pushbutton
LP1 Filament Lamp 12 or 24V
The objective of this circuit is to create a sequential lighting pattern in which LEDs or lamps illuminate one after the other. Its key feature is its high versatility, allowing you to construct a loop with any number of LEDs or lamps, with each illuminating device having its own individual circuit.
The diagrams depict three-stage circuits for the sake of simplicity, but you can expand the number of stages indefinitely (as indicated by the dashed boxes), provided that the output of the last stage is connected back to the input of the first stage, as illustrated.
The purpose of pushbutton P1 is twofold: It ensures a reliable initiation of the sequence during power-on, and when a large number of stages is used, it also enables the illumination of multiple LEDs or lamps simultaneously, such as having one device illuminated and three others turned off, and so forth.
Upon power-up, P1 should be kept depressed until only the LED or lamp associated with the module to which the pushbutton is connected remains steadily illuminated. Once P1 is released, the sequencer commences its operation. If P1 is briefly pressed after the sequence has started, you can achieve various sequence patterns, depending on the total number of stages in use.
If you opt for a single LED per module, the voltage supply can be in the range of 6 to 15V. However, if you plan to use multiple LEDs per module, they must be connected in series, and the supply voltage should correspond to the number of LEDs.
For instance, when using a 24V supply (which is the maximum allowable voltage), you can connect approximately 10 LEDs in series for each module. At 15V, around 7 LEDs can be used, and at 12V, it’s advisable not to exceed 5 LEDs per module.
The exact number of LEDs required may vary based on their color and the desired level of brightness. When employing lamps instead of LEDs, the voltage supply can range from 9 to 24V. Naturally, the voltage rating of the lamps should match the supply voltage.
In any scenario, lamps can also be connected in series. For example, four 6V lamps wired in series can be connected to each module and powered by a 24V supply. If you intend to utilize lamps that draw more than 400mA of current, you should replace the BC337 transistors with Darlington types like BD677, BD679, BD681, 2N6037, 2N6038, 2N6039, and so on. Darlington transistors typically include a built-in Base-Emitter resistor, allowing you to omit R1 and reduce the overall component count.
To adjust the speed of the sequencer, you can vary the value of C1. A similar design was published approximately four decades ago, utilizing germanium transistors and low-voltage lamps. The modern version, which employs LEDs, silicon transistors, Darlington transistors, and a 24V supply, represents an interesting improvement.