5 Awesome 555 Circuits!

With today’s proliferation of inexpensive microcontrollers and dev boards, it’s rather easy to program an Arduino et al. to do a simple task like blinking an LED. At the same time, one can understand the “just use a 555” sentiment that often arises when microcontrollers – capable of so much more – are used for such mundane applications. Rather than simply complaining about the state of hacking and/or overuse of microcontrollers, in the video below, Doctor Volt shows us how to use the 555 in five implementations that may be new to you

The first four 555 circuits/applications in the video include button debouncing, using a button as a toggle switch, undervoltage protection, and 555 use as a resettable fuse. At around the 4:30 mark, Doctor Volt uses two 555 timers, along with an IRF9540N MOSFET as an undervoltage protection plus fuse circuit on a custom PCB. Three trim pots enable him to set the discharge cutoff level, the battery full level, and the current level at which the fuse will blow, e.g. when the 555 circuit cuts off current flow. The fuse circuit is easily reset with a pushbutton, allowing the light that it is powering to turn on again.

The fifth 555 application is a simple amplifier circuit, which Doctor Volt illustrates with an oscilloscope and a speaker. The difference between the input signal and its output is demonstrated audibly at around the 8:20 mark, with the output sounding much louder – as it should. While any/all of these applications may or may not be immediately useful for you, it’s always good to have new options available as you never know when they will come in handy!