Breadboard Tip: Simple LED Substitute for a Logic Probe

P.S. LEDs are available with integral resistors. This list contains a selection of 5.0 VDC devices for your consideration. In the picture below you can see the internal resistor inside the LED body of the Lumex LED.

Note that this option is not popular as the internal resistor limits flexibility. It locks in a particular current and resulting brightness. Based on device availability, it is apparent that the majority of circuit designers prefer to use an external resistor. Still, there are specialized application where minimizing the number of BOM (Bill Of Material) line items is important.

As counter example, a LED with an internal resistor would not be usable for application such as multiplexing where increased but pulsed current are important.

Best Wishes,


The internal resistor can be seen inside the LED body.