This is my first circuit designed from scratch (that actually does something interesting), so please be patient with the beginner's mistakes (and maybe point them to me).
My circuit is the following:
What the circuit does is:
- When switch SW1 is open, the D2 LED turns ON and the D1 led turns OFF
- When switch SW1 is closed, the D2 LED turns OFF and the D1 led turns ON (they switch state)
Most probably this circuit has a common name (astable ?) but I don't know it.
I've tested the circuit at 9V (with R1 & R2 at 470 ohms) and it workes like a charm.
This circuit will be used with Raspberry-Pi's GPIO. Basically, the SW1 will be replaced by a GPIO pin.
My questions are:
- Is it ok what I did there with Q2 by not using any resistor for the base ?
- Considering that the GPIO pin will create a -3.3V drop when ON and the GPIO on Rasperry-Pi has no protection (AFAIK) and the 3.3V is supplied by the Raspbery-Pi itself: is this circuit safe for my Raspberry-Pi ? I've read in some place that by drawing to much current from GPIO may brake the device, but I still didn't wrap my head around how a circuit may draw more current than what it's given :(