SJR Looper – Schematic, tests + new circuitboard
A set of tests for my ‘any coil’ version of Lasersaber’s SJR Looper. Includes observations, different coils, built up circuitboard, microwave run, coil winding pictures, circuit diagram.
The middle coil may not be acting as the resistance in the circuit, but appears to function as such. I refer to ‘back collapse’ and that is simply my understanding of an LED lighting in both directions when a large turns/resistance coil is in a transistor circuit.
Measured ohms of the 2 middle coils shown –
Scruffy one 17ohms
Better made 15 ohms
Several transistors have been tried and 2N2222A are on their way.
C1815, C3332, S9014, S8050, all have shown a similar performance, with C1815 performing best by approx 10% so far. Light output and duration are very similar, no matter the small signal transistor type tried as yet.
A note to Stefan (OU.com)…the LED’s remain lit for up to 10 minutes on both circuits, but from around 3 minutes the camera isn’t sensitive enough to pick up the low lighting. Also, the battery in this old Kodak camera is past its prime. As such, a run is considered only until lthe brightness fades off and shows no signs of stabilising or indeed increasing.
My alterations to the circuit merely allow some explorations of different core materials and windings, they don’t represent the running performance of Lasersaber’s actual circuit…at least not yet 🙂