Constant Current Power Supply

I wanted a constant current battery charger for the C-cells that I use with my FT290R and FT790R. This is by far the simplest that I could make. It requires a LM317 and 10 Ohm resistor to give a constant 125 mA, ideal for battery charging. The output has crocodile clips, so that I can connect to, say a PP3 or leisure battery. The input voltage needs to be 3-4 V higher than the output, so for charging a 12 V battery a 15 or 18 V PSU would be ideal.

Construction details: Connect the 10 Ohm between the output and adjust pins of the LM317 and take the constant current from the adjust pin.

Next steps: Add a jack plug so that the batteries can be charged in situ. I am a little nervous about charging them inside the rig and prefer to have them where I can see them!