Hi everybody,

And perhaps the speed of the train is also controlled by PWM 😛

The circuit proposed now is probably the best we can achieve with the Lectron basic set. At minimum settings of the potentiometer, we have about 5% duty cycle. At maximum, it’s about 95%.

The meter after the low pass filter shows a DC voltage ranging from 0 Volts to a 5 Volts.

From the diagram, we see that the two 100K resistors are lowered to 10K. This change of value causes the capacitors to charge and discharge faster, resulting in (almost) perfect PWM.

I’ve also added a 47 Ohm resistor to protect the lamp.

The meter indicates voltages from 0 Volts to 5 Volts (2 x 100K resistors in parallel).

The lamp smoothly lights from dark to very bright 💡

And here’s the circuit, build in only 2 minutes !

PWM to anaV2

Here’s also a small video of the circuit in action : Lectron PWM

Many greetings