Thread: Victor 884
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Unread 26-01-2003, 22:52
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transorbers and emc?

I can think of 2 more reasons to get rid of the 883's

The 883's came in 2 flavors "red" and "blue" The older ones (can't recall which was which) required an external transorber to suppress transients to the rest of the wiring harness. Perhaps they just got tired of having to explain to inspectors when to look for external transorbers and when not to?

A more serious issue may involve electro-magnetic compatibility.
The 883's had a PWM frequency of something like 1000 Hz (perhaps more, again, memory fades...). Victors use something more like 100 Hz.

I am only a mechanical engineer, but I think that the following two things are true about this change in frequency:

#1, Your motors will start to move at lower duty cycles at 100Hz than and 1000Hz (in effect, the motor's time constant acts like a filter that filters 1000 Hz more effectively than 100 Hz)

#2 1000 Hz will act more like a radio station than 100 Hz

It is my understanding that Innovation First is working on new radio system for their EduRobotics that they are looking to migrate to their FIRST product.

Lower EMC problems may be an important factor in making the switch.

Finally, Innovation First may just be tired of supporting the older product. If this is the price of keeping Innovation First in the business of making control systems for FIRST, it is well worth it. As an 8 year veteran, I can say without hesitation that we are much better off with Innovation First than without them.

In any case, it is a hardship, but it is not an undue one (imho) especially since we have the K3 rule limiting how crazy we can get with extra Victors anyway.

Just my 2 cents.

Joe J.
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