Now and again modelers looking to add something special and individual to their layout will want a miniature arc welding simulator. This project demonstrates that you need barely anything more than a microcontroller and the right software.
The circuit shown here uses a PIC10F200 microcontroller to illuminate LEDs D1 and D2 with differing frequencies and time lags. To ensure the effect produces the characteristic flashes of arc welding the two LEDs should be fixed as close together as possible. The insertion and removal of the welding electrode are represented by short breaks in the flickering. To cut off the welding light the circuit we must either remove the supply voltage or else ground pin 8 (GP3). J1 provides an elegant approach to the latter solution. The welding effect is active with the jumper removed.
The software for the microcontroller can be downloaded free from the web at [1]. The configuration of the PIC is included in the ASM file but can also be carried out by setting all configuration bits to zero manually.
[1] www.elektor.com/110085
