When I build a solderless breadboard, I like to have an indication of when power is applied, and even better, what the voltage is when the supply is connected.
This simple, low cost panel meter costs less than $0.60 and comes in different colors. It is available from aliexpress. It is rated for up to 30 V DC.
I find it useful to make a few small modifications to it so it can be inserted into a solderless breadboard. Watch the video to see all the details.
