Thinking about dyno's for brushed motors

[Frankentruck]

The laser on my DT-2234C+ photo tachometer had gotten too weak to reflect a readable beam back. I discovered that I could hold a separate laser pointer and use that for a signal beam. In the process of tinkering, I applied reverse voltage. That almost immediately let the magic smoke out. Wow that smelled bad. Now back to proper polarity, the laser is nice and bright again but the display readout is dead. Oops.
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[Dadio]

Looks like just one component , do you want me to identify the part number on mine so you can repair it ?

[Frankentruck]

Hmmm... that's tempting. I did buy it from the cheapest source I could, but it's a shame to throw things away. If you could ID the part, that would be great.

[brown91]

Hey guys, complete newbie here. Can someone enlighten me on the process of dyno-ing a motor? I understand you are trying to develope as many rpms as possible at a certain test voltage, but why does the amp draw matter? Obviously the more amp draw you have, the more it will drain the battery, but is there some sort of relationship or proportion to voltage that is ideal? I guess what I am asking is what is the ultimate goal of adjusting the timing? Is it to get maximum rpms at a certain voltage with a certain amp draw?

[Dadio]

The amp draw goes hand in hand with temperature increase , its easy to wind on a lot of timing to make a motor run faster but it gets very hot therefore inefficient and the motor cooks and dies , there's a sweet spot with timing where it increases rpm without drastically increasing amp draw , the trick is to find that sweet spot just before the amps go up exponentially . For this you need an amp meter , RPM meter , good consistent power supply and ideally a load .