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#16
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Re: Non-FRC Motor Controller?
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http://en.wikipedia.org/wiki/User:As...novation_First "The Spike relay, available in mechanical and solid state models" In any case the flaky documentation aside (here's a video of PWM driving a solid state relay...it's not ideal but under just the right circumstances it'll work): http://www.youtube.com/watch?v=LL2Sryi57xA I suspect that the confusion was caused because Innovation FIRST does sell a solid state module, but I don't see any evidence that it's called a Spike relay. The Red Spike seems to have had no reverse polarity protection according to what I could find. The Blue Spike fixed that apparently. If that's incorrect please do correct me because Innovation FIRST Spikes are not something I usually mess around with, so my experience with all the flavors is limited. Last edited by techhelpbb : 03-05-2012 at 20:44. |
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#17
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Re: Non-FRC Motor Controller?
If you describe the projects in detail, we might be able to give you some suggestions. Otherwise we're all just guessing, which is not very helpful.
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#18
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Re: Non-FRC Motor Controller?
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The example you gave is a perfect example as why caution should be used. As far as I know, they have always been mechanical contact relays. You can find some Technical Specs on this page. |
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#19
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Re: Non-FRC Motor Controller?
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http://www.chiefdelphi.com/forums/sh...2&postcount=13 The term H-bridge shouldn't even apply to this unit anyway. An H-bridge is a very specific circuit. http://en.wikipedia.org/wiki/H-Bridge This is at best a half bridge or half h-bridge. I suppose if this were transistors you could also see it referred to as a totem pole, push-pull or class AB amplifier configuration. However, to keep this on topic as I stand corrected on the details: http://www.youtube.com/watch?v=LL2Sryi57xA A solid state relay *can* be used to control motor speed under the right circumstances and Innovation FIRST does sell one (I've just never tried it with this relay and we don't know what kind of motor): http://www.ifirobotics.com/ssr.shtml Last edited by techhelpbb : 03-05-2012 at 18:07. |
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#20
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Re: Non-FRC Motor Controller?
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Last edited by Nikkocharger : 03-05-2012 at 23:21. |
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#21
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Re: Non-FRC Motor Controller?
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#22
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Re: Non-FRC Motor Controller?
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http://www.robotmarketplace.com/prod...sersManual.pdf Seriously, this is professional documentation and it does not mention mechanical relay or solid-state. However, it does incorrectly refer to itself as an H-bridge which as you and others say it is not. Should I also know better than to read Innovation FIRST documentation and take it for granted? I've already stated I stand corrected on that detail....are you interested in the validity of my original suggestion which I provided a video demonstration for or something a little less gracious and professional? http://www.youtube.com/watch?v=LL2Sryi57xA Again: A solid state relay *can* be used to control motor speed under the right circumstances and Innovation FIRST does sell one which apparently someone...somewhere thinks is called a Spike (I've just never tried it with this relay and we don't know what kind of motor): http://www.ifirobotics.com/ssr.shtml Last edited by techhelpbb : 03-05-2012 at 18:53. |
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#23
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Re: Non-FRC Motor Controller?
these are all pwm esc's
for less than 1a http://www.fingertechrobotics.com/pr...d=ft-tinyESCv2 3-9a http://banebots.com/pc/ELECTRONICS/BB-0309 the sabertooth 25 is a pretty beastly dual channel controller. it will do 25a per channel or 50a single. i run one in my 30lb battlebot. http://www.robotmarketplace.com/prod...ER2X25-RC.html the 12 amp version isn't too bad either. for bigger stuff http://holmeshobbies.com/product.php...4&cat=2&page=1 it will do 80a at 24v and dosent have a fan like a victor. robot market place has a pretty cool tool to find speed controllers http://www.robotmarketplace.com/prod...lers_main.html http://killerbotics.com/kbtools/TentacleTools/ is a great drivetrain calculator. i would invest in a esc instead of pulsing a spike relay and you can always re use them in another project. |
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#24
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Re: Non-FRC Motor Controller?
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I was under the impression from the Innovation FIRST documentation and the Wikipedia page I linked it was a solid-state H-Bridge it is not (if you really need details why read posts from start of topic). My earlier error removed: If you pulsed the Innovation FIRST *solid state relay* with just the right circumstances you could control brushed DC motor speed with it. http://www.youtube.com/watch?v=LL2Sryi57xA BTW thanks for the reminder I couldn't remember that SaberTooth's name...they apparently ran out of big cat names so they went to extinct big cat names .Last edited by techhelpbb : 03-05-2012 at 19:24. |
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#25
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Re: Non-FRC Motor Controller?
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The usual meaning of "motor speed controller" in this context is something which takes a hobby servo control signal and provides a suitable modulated and polarity-switched output. Using a solid-state relay is a lot like using raw transistors; you need to provide your own PWM. And you're not going to be able to control the motor direction with one. Quote:
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#26
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Re: Non-FRC Motor Controller?
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The other point taken as well, normally you'd expect your electronic speed/motor controller to operate on the input signal and condition the result for the output. Perhaps even give you some features like thermal protection. Still without more detail we don't know what's expected. Several of those R/C speed controls will differ slightly in how they react as well. Additionally I've assumed again he needs to drive a DC brush motor. I hope that the difference between that and a DC brushless motor has been realized. These two kinds of motor are rarely interchangeable unless the controller for the brushless motor is part of the motor. Quote:
I'm almost positive that this confusion is not new either. I recall vaguely a previous topic in these forums with a similar issue Spike relay related issue. Sorry didn't mean to step in the same mess again. Last edited by techhelpbb : 03-05-2012 at 20:00. |
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#27
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Re: Non-FRC Motor Controller?
OK,
Here goes... The Red Spike which has not been sold for quite a while (+12 years) had a small limitation in that while it could reverse polarity to the output (M+ and M-) it could not independently switch from positive voltage to common. (It could make both outputs common) The Blue does allow that and so it has four states, one is both outputs high (+v), one is both outputs low (common), one where one output is high and one is low or one where the last condition is reversed. Spikes have never been solid state. In the strict definition of an "H" bridge i.e. four independent switches, the Spike meets that definition. It is simply two single pole, double throw relays, with the common terminal of each connected to the M+ and M- outputs. The nature of the self resetting breakers used in FRC allow a 600% over current rating for up to 2 seconds before trip when at ambient temperature. That is 240 amps for the 40 amp breaker. It is likely that you will not experience a trip even at 45 amps. The CIM motor is rated at 133 amps in stall, and free speed current of almost 3 amps. While you would think that software might be able to pulse the relay, in reality, the time it takes to move the contacts might make this a frustrating experience. When used with higher current motors, those above the rated 20 amps, significant arcing of the relay contacts will result from the inductive loading of a motor switched at a frequency needed to control motor speed. Used in this operation, the resulting degradation of the contacts may even fuse the contacts in some cases, rendering the relay permanently in one state. Please note that while a single solid state relay is capable of switching the current to the motor, it is not capable of reversing the motor. An "H" bridge could be constructed using four such solid state relays. The cost of the four devices and drivers would approach the cost of a Victor or Jag. However one needs to be careful to use SSR designed for switching DC loads and rated currents. Please note that the IFI SSR linked above is rated for 7 amps. |
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#28
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Re: Non-FRC Motor Controller?
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Again, sorry about the confusion. |
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#29
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Re: Non-FRC Motor Controller?
Thank you all for your input.
One last question: If I can't pulse a relay, is it feasible to pulse a bunch of MOSFETs? The data sheet at sparkfun says the switching delays are < 1us As long as my pulse period is in the ms order of magnitude than I should be fine, shouldn't I? I don't see propagation delay having a measurable impact here... Just need to make sure to have flyback diodes, right? Again, my experience with electrical stuff is all theoretical digital logic stuff, so your input is appreciated! This is what happens when a code monkey tries to actually make something ![]() Last edited by rbmj : 04-05-2012 at 11:33. |
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#30
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Re: Non-FRC Motor Controller?
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Do you need forward *and* reverse or just one direction? |
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