Hi all, I'm making a circuit based on this schematic:
http://www.qsl.net/yo5ofh/hobby circuits/circuit pictures/555leds.gif
It works, but I don't really understand the lower transistor functions.
What really confuses me is why the LED attached to the pnp transistor base is needed, and more to the point why is it when I replace the LED with a diode it doesn't work.
Many thanks,
Ewan
http://www.qsl.net/yo5ofh/hobby circuits/circuit pictures/555leds.gif
It works, but I don't really understand the lower transistor functions.
What really confuses me is why the LED attached to the pnp transistor base is needed, and more to the point why is it when I replace the LED with a diode it doesn't work.
Many thanks,
Ewan