Randy Hunt wrote:

> In article <usekh114fbrkbecrjq0fm3v766hoim5gfc@4ax.com>,
> xmrichmond@xaustin.xrr.xcom says...
>
>>On Sat, 3 Sep 2005 17:01:35 -0700, Randy Hunt <rhunt960@tco.net>
>>wrote:
>>
>>
>>>The 'Old' Dwell meters were usually based on continuity testers. I
>>>suppose you could measure continuity with it. I have seen articles in
>>>the electronic trade magazines about using Volt-Ohm (V.O.M.)meters for
>>>measuring point dwell. This was back in the late sixties and early
>>>seventies. I know I'm showing my age here.
>>
>>Young whippersnapper!
>>
>>My dwell meter scale read in degrees. I never took it apart but my
>>guess was that it was some sort of RC circuit (or maybe IRC) with a
>>voltmeter reading the potential across the capacitor. The longer the
>>dwell, the more charge the capacitor would accumulate, and the higher
>>the voltage, which would then read as a larger dwell angle.
>>
>>
>>Elliot Richmond
>>Freelance Science Writer and Editor
>>
>
> Some of them would simply let the longer the dwell be indicated by the
> lower resistance read.

There should be no change in resistance - either it's infinite (points
open) or near-zero (points closed).

> Letting the mechanical inertia of the meter integrating the pulses
> into a smooth reading.

That's how almost all tachometers work.

>
> Randy


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