Measure your blowing power

thingiverse

This is not a medical instrument, that is why it is listed under toys. It is fun to compare the blowing power of different people. The airstream will rotate a fanblade linked to the shaft of a small DC motor, which acts as a generator. The current charges a capacitor. To prevent dischargeing over the DC motor, a diode is inserted. In this way, if you have a capacitor with low leak, the value can be measured more easily. The output voltage is in the order of 5 volts. Instead of using a multimeter, a led scale can be applied as well. A push button over the capacitor discharges the capacitor and the circuit is than ready for a new measurement. By replacing the two resistors by a 5K trimpotentiometer, the sensitivity can be changed. A box design is up to you. https://youtu.be/VyUaCc8frQk