Does anyone know what the major difference is between the 883 and 884 Victor. We now have a box of “useless” 883’s and have to buy four more 884’s at $115 each. This recent revelation is really putting a damper on things and would be more palatable if the difference was truly necessary.
I thought i saw somewhere that the 883s had a deadspot where you had to apply a certain amount of power before they would actually kick in.
Here’s an ASCII of what I think the difference is in PWM width vs. requested counts:
883
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884
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Basically, I think both have a dead spot with the 884 having a smoother transition from the dead spot to an active state.
I think I read somewhere that you can only use 884s for this year’s competition, not sure but you might want to check the manual or something.
The Victor 884s are capable of up to 40 amps, rather than 30 amps, and they also have a power range of 3%-100% rather than 10%-100%.
According to Innovation First, this should mean better (more precise) arm control.
Kevin, is your team interested in selling your old 883’s?
No, we just think its unfair to not let us use them for the motors that dont require 40 amps, some of us are personally paying for parts out of pocket due to lack of funds, and just having these lay around and not be able to use them is bad. We dont like the idea that we are forced to buy more from innovationfirst even though they are not a safety hazard and will work just as well. I begin to wounder what the exact pourpose of that rule was trying to accomplish, as far as I can see - only to force us to buy new things we already have just so they can make more $$$
No, we just think its unfair to not let us use them for the motors that dont require 40 amps, some of us are personally paying for parts out of pocket due to lack of funds, and just having these lay around and not be able to use them is bad. We dont like the idea that we are forced to buy more from innovationfirst even though they are not a safety hazard and will work just as well. I begin to wounder what the exact pourpose of that rule was trying to accomplish, as far as I can see - only to force us to buy new things we already have just so they can make more $$$
I agree completly, we have about 6, 883’s just lying about and can’t use them. It’s rather frustraing:(
hooray for rookie teams who don’t have old parts 
i wish i could help you guys out. the best thing i can tell you is put 'em on ebay…battlebots people eat those things up. you’ll atleast make a little money back…
*jeremy
I can think if several reasons for the ruling.
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It makes it easier for judges. They con’t have to INSPECT to make sure you have a particular speed controller n a particular motor on a particular fuse.
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Its called leveling the playng field. It will keep older teams from having such an advantage over rookie teams.
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Then there is of course safety…probably the big reason. Another 30% current is not insignificant…(though safety also goes along with reason #1)
-Quentin
*Originally posted by RebAl *
**No, we just think its unfair to not let us use them for the motors that dont require 40 amps, some of us are personally paying for parts out of pocket due to lack of funds, and just having these lay around and not be able to use them is bad. We dont like the idea that we are forced to buy more from innovationfirst even though they are not a safety hazard and will work just as well. I begin to wounder what the exact pourpose of that rule was trying to accomplish, as far as I can see - only to force us to buy new things we already have just so they can make more $$$ **
What would it matter about inspecting it? The current limit on the 883s is lower. It would actually be safer. It wouldnt really matter about what breaker you put upstream from it. No need to inspect. There was no extra inspection when a team used 884s instead of 883s last year.
Allowing would level the playing field because teams with less money could afford to have more speed controllers or hold them as backups.
*Originally posted by bigqueue *
**I can think if several reasons for the ruling.
It makes it easier for judges. They con’t have to INSPECT to make sure you have a particular speed controller n a particular motor on a particular fuse.
Its called leveling the playng field. It will keep older teams from having such an advantage over rookie teams.
Then there is of course safety…probably the big reason. Another 30% current is not insignificant…(though safety also goes along with reason #1)
-Quentin **
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The electrical system should have all the wires traced anyway to make sure it is the proper gauage for the motor and fuse used, and the maxi breakers are hard wired anyway so finding their attatched victors shouldent pose a problem, just in the same way they must trace a relay to a motor to make sure it is legal
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It would be less of an advantage because it does not have the same current and it does not allow you to use all of the power as mentioned above, only advantage would be not having to pay $$ but at the same time having a old victor
3)If the victors are attatched to the correct fuses there is no safety hazard
Also what if a team bought 5 victors from years before, are they useless just because they dont have the same features that first feels we need? I guess our team will have to cut down spending in other places, like for the nats because of this extra 650+ expence.
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.
Put the 883’s on ebay. They should sell for at least 50 dollars a pop. Ive heard that there was a team once that did that and they got back 60-65% of the value of them from the auction. Have the winner pay shipping and you could make back a nice sum of money
[edit] On EBAY I found a set of Victor 883’s for $175 for a set of 2…they do sell. (The guy put BATTLEBOTS in the title, but whatever sells them) [/edit]
>>On EBAY I found a set of Victor 883’s for $175 for a set of >>2…they do sell. (The guy put BATTLEBOTS in the title, but >>whatever sells them)
Those were probably not the 883’s you guys have laying around.
Check out http://www.ifirobotics.com . That’s the non-FIRST (ie BattleBots) side of Innovation First. They have a 24V Victor 883 that is rated at 60A.
You’re right though, the BattleBots folks will buy the old 12V 883’s–the lower weight classes robots (30, 12, 2 and even 1 lb) are getting popular.
Dan
Try eBay in the RC car section. People pay way too much money for speed controls in there.
Thanks to all for your insightful responses. Although no ONE answer seems to be enough to justify forcing all teams to stop using the 883’s, collectively, the arguments make it easier to agree with their decision.
Now, just keep your fingers crossed that we won’t have 885’s next year!
All in all the 884 is such a big improvement over the 883 it warrants the change. But there is other factors to consider…
Innovation FIRST has always been very helpful in replacing suspect components, helping research problems and truly listening to their customers, US. The 884 is a direct response to those requests in that it is a higher current, less deadband, more fine control version of their previous products. If you were at a competition this year, had used an 883 with the expected deadband and ran into a problem you thought was a speed controller, would you want to just drop in an 884 and hope it would be OK or would you want to get an exact replacement device?
Joe Johnson hinted that the output signal was about 1000Hz, and I found a data sheet from a few years back that stated it was 2000Hz for the '00 883. Although I have not seen any discussion on this subject (and would welcome that from a knowledgeable source) I would expect an interaction between frequency of switching, brush/commutator length, motor speed and ultimately accuracy of control. The 884 is theoretically attempting to optimize all of these factors and give us higher current outputs.
Thats all good but what if we dont need all of those things? Why are they forcing us to use 40 amp victors on 30 amp breakers (we can’t even get the full usage of the 40 amps if we can only use 30 amp fuses), it makes no sence to me that we cant have something worse then other teams have if we want to, there is no unfairness to that besides the fact that these victors that we need to buy now might keep us from going to the nats just because now the playing field is unleveled between us and those with large sponsors that can afford more.
-no saftey risk
-poorer operation
…how could that be unfair to other teams if we used them??
We do get 40A fuses this year, though.
While we do get 40 amp fuses, we only get four.
My team is using an 8 motor drive train, with 2 other non drive motors. Only 4 of those acutaly are able to take advantage of the 884’s higher current rating (which I think is a silly idea anyways, but thats another post). So here we are, forced to buy at least 6 more of these things that are over rated and completly unnessecary. Its a huge chunk of our budget that we are forced to give up.
If FIRST wanted to get rid of 883’s, fine, but wouldn’t it be better for all of us if they were phased out? This year for instence, only 884’s could be used on the 40 amp motors, with 883s being legal on all the others. Next year, move the FP up to a 40 amp breaker (which it should be on anyways) and so on, untill teams have had the chance to spread the cost of new 884’s over a few years.
Frankly, I’ve been nothing but happy with the 883’s. I’ve never had a problem with one frying because of to much current (and our 02 bot was a current monster), and I’ve always found them to be plenty accurate.
-Andy A.