Michał Słomkowski developed a pyrotechnic firing circuit using the dial bell generator from an old military field telephone. The generator charges a capacitor bank through a bridge rectifier, while the thyristor transfers the stored energy to the filament, enabling ignition.
The circuit also includes a charging indicator consisting of Zener diodes and an LED, as well as a test setup powered by a 9-volt battery that checks the filament without triggering ignition. The old project was recently republished on Słomkowski’s website.
Why it matters
This project shows that a piece of military communications equipment no longer used for its original function can be adapted to another setup requiring energy generation and controlled discharge. The separate roles of the bridge rectifier, capacitor bank and thyristor are based on storing mechanically generated electricity first and then transferring it, rather than sending it directly to the firing circuit. The charging indicator and the 9-volt test line, which checks the filament without igniting it, show that the design focuses not only on operation but also on preliminary testing. The project’s republication makes its technical details accessible again to those interested in evaluating old hardware for different purposes; however, it remains unclear whether the circuit was later updated or put through a new test.