Saturday, December 18, 2010

Bob Update: Number 2

I believe I have enough side issues corrected to do some driving. The turn signals work. The ignition key is installed. That took several days because it required modifying the column. The 914 has early versions and late versions, and they do not interchange. I bought a late column on ebay and the mounting holes don't match. The late switch and lock won't go in an early column without severe modification, which mine now has. The tach is working. I made an optical pickup and mounted it on the back face of the motor. there was only one hole available so I hope that is enough. I pre tested the output and got a perfect square wave going to the tach, but the tach still didn't work. I took the tach apart and modified it and now the tach works. I got lucky here because I had no schematic and was working blind. I wish I did have a schematic of a VDO tach. I'm not done with this because I want to make an adaptor which works without having to modify the tach itself. The next big hurdle before I order lithium is the charger. It has the wrong profile for lithium and I don't even like it for lead. My approach is current limit in initial phase, voltage limit, then stop when the current reduces to 10 percent of it's initial value. This for lead and lithium. This approach is even good for nicd and nimh although it is seldom used this way. Next, the low voltage schematic that was furnished with the kit is unreadable in it's present form, so I redrew it. I discovered what i think is an error and after I make some changes, I'll comment further.