I am new to electronics and this forum, and am in the process of building a Raspberry Pi based homebrew controller.
Following the article in the eLinux wiki, here is the relevant part of my circuit:
I have breadboarded this and it appears to function fine, however I notced that the spec sheet for the SSR calls for and extra transistor, between Q1's collector and the positive source:
Is this extra resistor necessary and what does it do in this circuit? If I need to add it, then how do I size it properly?
Thanks in advance.