Learn How to Make an LED “Chaser” Circuit Without Using Any ICs

Integrated circuit (IC) chips are dirt cheap these days, which means we makers have a tendency to rely on them even when they aren’t completely necessary. With affordable development tools like Arduino boards available, it is often easier to simply program a microcontroller to handle a basic function than it is to learn how more fundamental components can do the same job. Aside from being cheaper, discrete components also consume far less power than microcontrollers and other IC chips. It is absolutely worth learning how to take advantage of them. To that end, NEW PEW has put together a tutorial that will walk you through out to make an LED “chaser” circuit with using any ICs.

This circuit’s function is to blink LEDs consecutively. Specifically, it blinks three sets of three LEDs one after the other. This would be easy to achieve with a microcontroller development board like an Arduino. You could just connect each group of LEDs to its own pin and then cycle through which pin is active with each loop. But you can do the exact same thing using just a few discrete components that cost a nickel each. The only downsides to this approach are that you can’t adjust the timing without swapping out components and you can’t have any kind of irregular timing without dramatically altering this basic circuit. Those caveats aside, this is a fantastic illustration of how lowly discrete components can do a lot more than many makers today realize.

This is a type of circuit that used to be very common, but which has become something of a lost art as microcontrollers have taken over. It uses transistors with capacitors to handle the timing. Each transistor is triggered by the discharge of the capacitor, which results in very regular modulation. When a transistor is active, it allows current to pass to one group of LEDs. As each transistor is activated it charges its neighbor’s capacitor, so one LED group is lit after the other. This circuit only contains three LED groups, but you could theoretically add as many as you like. The timing intervals are dependent on the values of the resistors and capacitors used. Power comes from a regular ol’ 9V battery. NEW PEW freeformed the circuit, which looks very cool. But you can do the exact same thing on a breadboard if you just want to experiment with how a circuit like this works. We recommend that you do, because it is a great way to start becoming less dependent on ICs.