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Originally Posted by 142 Guy
2N 3055 - that is an ancient (mid '60s design); but, historically significant transistor (check Wikipedia for gory details). It is still in production; but, likely as a replacement only, not for new designs. You would probably want to adopt a newer design anyway because with its limited production it comes with a very high price considering its rather middling performance by modern standards.
It is not a darlington pair; but, it does have a rather disappointing Vce sat. At a collector current of 4 amps its not bad at 1 volt; but, it rises quickly to 3 volts at 10 amps. You could definitely do better with a more modern design.
You made the comment about reliability. I think the modules like the Pertronix provide a service reliability (defined as not failing) that is probably just fine. That is a separate issue from the performance degradation that you may suffer under starting conditions. That loss of performance may never be a material issue if the engine is kept in good tune, the battery is in good condition and you are not trying a start when it is -30C.
The Pertronix and similar modules will address the issue of timing drift and detrioration of performance as the ignition points wear. However, on old car like ours that completely misses the issue of wear in the distributor mechanicals. Sticky advance mechanisms and worn distributor shafts are a real issue. I ran with a Pertronix module on my B20E for a couple of years. The module worked just fine; however, when using a timing light to check the operation of the advance mechanism I found that above about 2700 RPM the timing was bouncing around about 6 degrees - it was hard to be accurate because the timing marks just became a blur. I removed the advance mechanism, cleaned, relubed and bench checked its operation. That didn't resolve the problem so I purchased a re bush kit for the distributor; however, I was never able to get the retaining pin on the end of the distributor out so I never re bushed it. I ended up adopting the nuclear option of implementing ignition control in Megasquirt with coil on plug and timing by slotted wheel and optical pick ups. An extreme option; but, my timing marks are now nice and steady.
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I only mentioned it because I have a stock of old parts including old PICs etc. Too tight to throw stuff that will 'do' in my projects away
Recently used some along with LM317s (also have shed loads in stock) to increase the current capacity of the variable supply I needed. Hey, I know there are 'better' products out there but to my tiny mind it helps to use what we have rather than throw it away simply because it's no longer vogue. I'm too tight & too old to do so
Now someone has mentioned it, it might have been the Elektor kit was used in my Morris Minor. I now seem to recall a slotted disc (as you used to find in computer mice) used for switching...