This circuit can be used to test up to three LEDs at once, connected in series. You can easily increase that number by using a higher supply voltage. If you do so, you should allow 2.7 V for each ...

A blast from the Elektor archives: this 1998 battery tester uses a simple LED display to reveal a battery’s true condition ...

Some 1.5 v LED flasher circuits are available on the internet and we like to present you four of them. The flasher circuits below operate on a single 1.5 volt battery. The circuit on the upper uses ...