—THE DETAILS—
The transmitter needs 3-5 volts.
The receiver needs 5 volts.
I want to use a 9 Volt battery for each since it is not a very large battery.
That means I’ll need a resistor for each.
—THE PROBLEM—
I am confused on how to get the correct resistor. I’ve read online all over the place. I already understand Ohms law V=IR.
When I measure the volts with a multimeter ‘before and after adding a resistor to a circuit’, I get the exact same voltage reading.
Can someone please help?
A resistor by its self will not provide any potential difference over the terminals. Ohms law will only apply to tell you the current through the resistor.
The simplest approach is to use a linear regulator integrated circuit, such as the classic 7805. You can also use a zener regulator for low current situations. Lastly, you can use a resistor divider, but it is incredibly inefficient if the device consumes any amount of current.
A 9V battery isn’t suitable for that application, unless you want to replace them frequently.
Leon
What kind of suitable battery would you recommend? Something that’s not very large and would last awhile…like[/quote]