Home › Forum › Ask A Member › How do Atom Computer Ignition modules work? › Re: How do Atom Computer Ignition modules work?
Dangit.
Well OK, I figured out why none of my circuits are working. The 2SD1071 I purchased from this eBay listing (item #181052048392) are F*A*K*E! I’ve built three so far, and (as with any good experimenter) in each case I chalked up the failures to my own errors, despite being unable to find any wiring errors in the modules. Solid-state isn’t my world, but even so, they +are+ pretty darned simple!
Recall my asking some time back, why they measured with an hfe of 20-25? Well, that’s because they do have an hfe of 20-25, as opposed to the (min.) 500 of a real 1071. These fakes also lack the internal diode, from E to C.
Be advised.. I’m now taking this up with the seller. I already left them a nice FB – in good faith, as they shipped promptly – so we’ll see how they act. In the meantime, I’d avoid that seller’s offerings.
FYI – Here is how I confirmed it.
15V variable supply. C tied to B+ / E tied to Gnd / B tied to B+ via 1K3 resistor. With the supply cranked full-on, Ib = 10mA and Ie = 200mA.. that’s a 20:1 ratio, which fits nicely with the measured hfe of ~20 for this particular device. I didn’t trust the component tester, but I sure do trust my own separate instruments. And I really doubt the whole batch is defective in exactly the same way.. the missing diode is the final nail.