LEDs or Lamps Sequencer

  
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The purpose of this circuit was to create a ring in which LEDs or Lamps illuminate sequentially. Its main feature is a high versatility: you can build a loop containing any number of LEDs or Lamps, as each illuminating device has its own small circuit. The diagrams show three-stage circuits for simplicity: you can add an unlimited number of stages
LEDs or Lamps Sequencer - schematic

(shown in dashed boxes), provided the last stage output was returned to the first stage input, as shown. P1 pushbutton purpose is to allow a sure start of the sequence at power-on but, when a high number of stages is used, it also allows illumination of more than one LED or Lamp at a time, e. g. one device illuminated and three out and so on. After power-on, P1 should be held closed until only the LED or Lamp related to the module to which the pushbutton is connected remains steady illuminated. When P1 is released the sequencer starts: if P1 is pushed briefly after the sequence is started, several types of sequence can be obtained, depending from the total number of stages. * Using 24V supply (the maximum permitted voltage), about 10 LEDs wired in series can be connected to each module, about 7 at 15V and no more than 5 at 12V. * If you intend to use lamps drawing more than 400mA current, BC337 transistors should be substituted by Darlington types like BD677, BD679, BD681, 2N6037, 2N6038, 2N6039 etc. * A similar design appeared in print about forty years ago. It used germanium transistors and low voltage lamps. I think the use of LEDs, silicon transistors, Darlington transistors and 24V supply an interesting improvement.



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