LOL! That sounds like
LOL! That sounds like something I could have done too! I really like the whole assembly - reminds me of my first line sensor where 10 LDRs where mounted on a piece of cardboard from a cpu box and the connections were a mess of unisolated wires :-)… why the hell did they invent boards to solder onto? Who needs them?! 
Thanks for clearing up the problem for us.
Hehehe, yup, I figured there
Hehehe, yup, I figured there must be something not shown in the circuit. I’ve just recently been messing around with some of those TO220-packaged darlingtons too (TIP120/122’s) , and it surprised me that the tab is connected to the collector, and not the emitter. I know transistors are often used in all different kinds of configurations, but it seemed like the most common arrangement would be with the emitter tied to ground, so if the tab were connected to the emitter, thena common heat sink like you have would work just fine. That’s how they did it on 7805 voltage regulators – the tab is ground, and that seemed to make sense. With the tab being the collector, I have to provide more space between my transistors to keep them from touching. Kind of a pain. Anyway, glad you got it working
Dan
