Good info, Richard! I'm glad to see that an aftermarket device has been developed that includes a current limiter- - - -GM used to insist that nothing but OEM modules be used for service parts because of overcurrent problems with aftermarket replacement modules. One economy measure the replacement parts people took was to eliminate the current limiter in their designs.
Here's another bit of trivia about dwell meters- - - -they're really nothing but voltmeters! When the points are open, the voltage at the distributor side of the coil, where a dwell meter is attached, and ground (where the other lead goes) is always going to be applied voltage because there's no current flowing. With the points closed, the voltage will be zero, because the points provide a ground for the coil primary. The dwell meter is reading an average of the voltage between points open and points closed, and the longer the points remain closed, the lower the indicated voltage will be. The "voltmeter" scale is simply calibrated in degrees of dwell, rather than volts. That's why some dwell meters need to have a selector for 4,6,or 8 cylinder measurement- - - -the meter has to discriminate between the number of times the points open and close for a particular engine. Other meters are self-calibrating.
"point resistance" is also important for good dwell adjustment. If the points are dirty or burned, the meter will not see a true "zero volts" reading at the points closed position, because a little voltage is consumed pushing the primary current through the points and the dwell indication will be inaccurate. Always be sure the points are new, or at least clean, before setting the dwell. Some meters include a "primary resistance" feature which involves checking the meter reading with the points closed and the ignition turned on before doing an adjustment.
Jerry
