We use a fair amount of Spikes in our builds, and we robbed our '13 and '14 robots for this year’s build. We want to keep both of those bots for demonstrations, and they both have 4-slot CRios (so they make nice programming development platforms) but I’m having trouble justifying buying new spikes when I imagine there is another relay available that is much cheaper and would work just as well. 2013, for example, has three motors in the shooter that all have individual Spikes…for a bot that never has to pass another FRC inspection, is there a cheaper option?
I’ve picked up relays at a local surplus store for various projects before. You can get them really cheap that way, but you have to stand in the isle a bit trying to google on your phone whatever model number you can find on the casing so you know it can handle the loads you’ll pass through it. For the most part they probably wouldn’t work as a direct, 1-1 replacement for a spike, but with some creative wiring you can get it to work without having to rework any code!
Define “work just as well”. If you’re looking for something with the same current rating, 5V inputs, and you don’t want to bodge 3-4 individual SPDT relays into something like an H-bridge, then I don’t think there’s actually anything available that’s cheaper than the Spike. There’s some multi-channel relay boards, but you’d have to rig up 4 of the channels on there to turn it into a Spike equivalent.
If you have spare ports on the pneumatic module they can be programmed in place of a spike. We did this on our bot last year to power/control our LEDs.
Good point - For me I’d like it to operate without a code change…but I wouldn’t mind possibly some wiring tweaks. 2013 we could run without pneumatics, because that was just used for the hang…and we won’t demonstrate that, but the three motors on individual spikes would be nice to replace with a single, higher capacity relay. 2014 had only our pneumatics on spikes. We never bothered with the pneumatics breakout board…maybe now is the time (even though it’s obsolete). I guess we’re going to have to re-program anyway so we don’t have to maintain old driver stations to run them.
You could run all 3 motors off one spike? If you’re amenable to a small code change, you could probably run them all off a single Victor/Jaguar/Talon. Just grab an outdated speed controller you’re not likely to use again and run them all off that. Provided the total current draw is less than 40A, anyways.
Something like this http://www.ebay.com/itm/4-Channel-5V-Relay-Module-With-Optocoupler-For-Arduino-DSP-AVR-PIC-ARM-/221658808205?pt=LH_DefaultDomain_0&hash=item339be4ff8dis good for 10 amps. That’s halfway there to the current rating of a spike. There may be larger ones out there.
This should NOT be able to handle the current draw of motors. LEDs, relays, and solenoids, sure, but not motors.