Greetings Moparians!
Having read The Oracle of the Honorable Mountain (Ehrenberg) on using the venerable 7805 IC regulator to replace the Victorian antique behind the gas gauge, I went in search of some 7805s to make up a few of these for folks.
New Egg carries stuff already done. I recommend these, as the 1.5 amp maximum from a single LM 7805 doesn't go far in our old dashboards, as "R.E." should know! I advise you to get a 10 amp supply, which will easily power any USB items you may...
Half-decent source for 5V regulated DC-DC converters!
