I don't know how to get the voltages +5V and -5V from a 24V battery.
A DC converter is needed for the minus rail, isn't it?
I'm a newbie, Please help! what can be put instead of the '???' block?
Hello Bertus, my needed current is less than 20mA. so a 78L05 will be ok. I connected one to 24V battery, it heated up soon!
Another problem is that I'm planning on using an ICL7660 to get the -5V supply. but its maximum input voltage is 10V. How do I connect it to the battery?
For your heat problem you can take a LM7805 in a TO220 housing.
That has a metal plate to spread the heat.
( you can enlarge the plate for better heat spreading by mounting it to the a copper or aluminium plate).
For the ICL7660 : take the LM7805 output as input for the ICL7660 (this is the 5 Volts).