Category Archives: Projects

Dead Battery

One of the Batteries from my Bosch cordless drill machine had died. I could buy a new one but that is rather expensive. So I opted to take the batteries out and put a cable on it. The cable plugs into my 12V power supply that powers my lights etc.

The cells inside (5 cells at 0V):

I have mounted a cable gland in the plastic enclosure from the old battery so I have a strain releave for the cable.

Plugged in the drill:

I added a diode to the power supply to protect my power supply against voltage spikes from the motor.

The downside of this is of course that I have a cable connected to it now. But I still have 1 battery that functions so I can still work wireless :p. But if I’m working at the workbench and the battery is flat, then I can use the cable to avoid waiting for the charger. Another downside is that my LED lights dim as I start the drill, this is because it draws too much current. The power of the drill isn’t as big as on the battery. My power supply delivers 12V while the battery does 14.4V.

555 Contest Entry

This is my entry for the 555 contest. I didn’t have much time to make something so the entry isn’t much.

This design is a fan controller. The base of it is a simple pwm circuit with the 555 timer. The problem with fan’s is that they don’t start at low voltages. So I added a capacitor (C2) to give it a little voltage boost at the startup.


The circuit can also be easily adjusted to have a soft start. This can be useful when driving led’s etc. This way the light is not instantly bright.