555 Astable SMD Trainer Instructions

555 Astable SMD Trainer Instructions

Table of Contents


What is the 555 Astable SMD Trainer?

The 555 Astable SMD Trainer kit is designed to test your skills at SMD soldering and provides you with a small circuit that blinks. The frequency of the blink is determined by the value of the electrolytic capacitor and the setting of the potentiometer such that the smaller the size of the capacitor or resistance value of the potentiometer, the 555 astable will flash quicker. To learn more about the 555 timer and how it works, you can check out the instructions for the 555 Astable kit from MitchElectronics which also includes the internal circuit diagram of the 555 itself.

Use this kit to test out your soldering skills!

What can you do with the 555 Astable SMD Trainer?

Besides the obvious use of improving your skills with soldering SMD parts, there are numerous uses for the kit. One potential application is to use the flashing LED as a night locator that can be attached to the back of a bag. Simply put, these kits can be ideal for quickly locating others at night during hikes in a similar fashion to tail and wing lights on planes. 

On that note, the 555 Astable SMD Trainer can also be used on model RC planes that want to replicate the blinking lights used to locate craft at night. The SMD LEDs, albeit small, are brighter than you’d think, and can thus be used as a visual aid at a great distance during the night. 

555 Astable circuits in general are also excellent for pulsing circuits that need to turn something on and off at regular intervals. One such example is a clock source for digital logic circuits that need a regular pulsing voltage (however, if using the 555 Astable with logic circuits, make sure the logic circuit operates at the same voltage as the 555 Astable otherwise you will likely damage the logic circuit).


Component List

ComponentPCB ReferenceQuantityLooks Like
555 Timer IC SOIC8IC11
0805 100R ResistorR21
0805 1K ResistorR1, R32
0805 100nF CapacitorC21
10uF CapacitorC11
100K PotentiometerRV11
0805 Red LEDD11
PP3 ConnectorJ11


Construction Tips

3D Printable Jig

To help keep the board stable when soldering, you can download a free STL model of a basic jig that can be 3D printed with all common 3D printers. Watch out for the mounting hole pins as they may be vulnerable to snapping if using a low infill density, low wall thickness, or thick layer heights. Additionally, do not use hot air to solder the PCB when using the jig as you will melt the jig.

SMD Construction Guide

To learn more about how to solder SMD components, read through the MitchElectronics SMD Soldering Guide found in our resources section

Component Order

When soldering the 555 Astable kit, you will need to pay attention to the following chapters in the SMD soldering guide (which can be seen here). You should also solder the components in the order shown below.

  • Integrated Circuits
  • Resistors
  • Capacitors (ceramic)
  • Capacitors (Electrolytic)
  • LEDs

Make sure that the LED, IC, and electrolytic capacitor are oriented correctly as they are polarised components. Inserting the LED in the wrong orientation will result in no light, and inserting the 555 IC the wrong way round will overheat and break. Components such as the resistors can be soldered in any orientation, and the potentiometer can only be inserted in one direction due to the use of 3 unevenly spaced feet.

Finally, ensure that you connect the battery connector correctly with the red wire connecting to the + terminal, and the black wire connecting to the – terminal.