Hi guys, been waiting or some components (mosfets) to make this work as well as a darlington array as an alternative.
I came a cross the schematic below and did some reading and watched some videos on the zeener diode below. I understand that R1 is limiting the current for the LED inside the opto, and I also understand that R2 sets to voltage drop for the Zenner to work and let only 4.7v pass to the opto. However I have not been able to find information on how to "size" that resistor or how it related to the zeener (other than what I mentioned).
In this circuit Vcc is 12V.
1- I need some guidance with respect to a schematics drafting software with simulation. The past week and I have been using LTspice which is free, but does not have many components and seems very "manual" to use. Is there an industry standard or something a little bit more advance even if its a paid version?
2- I noticed that many times when using a transistor to turn on another transistor, depending on what type of transistor the 2nd transistor is (NPN, or PNP) it needs to be either placed at the collector or emitter of the first transistor. Is this a correct statement?