I looked at the standard LM317 setup at http://www.learningaboutelectronics.com/Articles/LM317-voltage-regulator (where the center of a voltage divider is connected to the adj pin and the inputs and outputs each have their own ripple filter capacitors).
What fooled me was when I used a 12VDC adapter to power my charger circuit, the voltage reading from the voltmeter was 18VDC even though the label on the adapter is 12VDC.
I used the same LM317 setup to try to achieve roughly 7.5V (but my R1 is 330 ohms and R2 is 1800 ohms and both are 1W) but when I used my 12V adapter, the measured output voltage was 10.5V which makes me think I'll explode my batteries since I'm charging two at a time and each one is 3.6V nicd.
I then proceed to read http://www.apogeekits.com/power_adapter_selection.htm and it states that my circuit must use the same current the adapter must provide (800mA) in order for the true voltage to be read from the adapter.
It also states that the adapter I have is unregulated. Rather than me trying to find (expensive) regulated adapters, is there a way I can alter the simple LM317 circuit or even change from one adapter to another so I can see 7.5V at the regulator output? or can I keep my existing setup and increase some resistors?
Eventually I'll have a complex circuit and for the most part, the maximum current consumption for the output elements will be in the order of milliamps.
This is the initial question to the charger I made:
but I made a new post because my problem now is directed to the power supply.