Re: Multiplex Festo Valves
 

Don,
I was responding to using 24 volts to control solenoids through Spikes. Sorry for the confusion.

Re: Multiplex Festo Valves
 

MAN!!! Up until yesterday night I managed to ignore the pneumatics rules and caveates.

When they had issues, I assumed that it was simply a matter of the folks on my team not reading the manual(s).

Now I see what a morass that the pneumatics really are. From finding the right valve to order to staying legal to drive voltages to relief valves to M5 fittings to Kansas City and Back again... ...this stuff is simply not easy.

There are a lot of advantages if you get through the learning curve (and then stay ahead of the changes), but whoa, I don't know how mere mortals (i.e. about 50% of the FIRST Teams) can do anything much beyond using the stuff in the kit as is and ordering a few Bimba's...

Joe - the mortal - Johnson

Re: Multiplex Festo Valves
 

You need to look more closely at what comes in the Kit.
Teams can't actually put together a pneumatic system from the Kit anymore.

Re: Multiplex Festo Valves
 

Yeah,

I was rather surprised to find no tube fittings at all in the kit.

Re: Multiplex Festo Valves
 

Don't ever run 24v through the SPIKES, legal or not they will fry in an instant.

Re: Multiplex Festo Valves
 

Depends on what you mean by "through" I think that on they are just standard dual SPDT relays typical of what is used to drive a window or seat adjuster on a car. I don't have one in front of me, but I would be surprised if they had any practical issue switching 24V -- there may be some life issues or some arcing inside the relay that is less than ideal but I am pretty sure that they are standard automotive relay which is to say that 24V will definitely not cause them to "fry in an instant"

Now, the control circuitry, that is another matter entirely.

24V may in fact cause something on the control circuit to fry in a New York Minute -- which everyone knows, is an order of magnitude LESS than an instant ;-)

Cheers,
Joe J.

Re: Multiplex Festo Valves
 

I have hooked up SPIKEs to 17-19 volt sources, not the signal, for NON FIRST projects. You'll hear a little pop, and the relay will never work again. =shrug= doesn't matter what part of the spike breaks.

Re: Multiplex Festo Valves
 

Ah, you remind me now. Getting old sucks* I forgot the driver circuit on a Spike is co-mingled with the power circuitry.

The coil on the relay draws its power from the hot side of the power circuitry. I think that the Spike has an onboard Darlington pair of FETs that provides a path to ground from the hot side of the power voltage through the coil of the relay. The "PWM cable" is nothing but a means of turning on the FETs.

Anyway, it is this circuitry that must not tolerate the higher voltage.

This is unfortunate for a several reasons but it is what it is.

Sorry for the bad info.

Cheers,
Joe J.

*well... ...only when you don't really consider the alternative.

Re: Multiplex Festo Valves
 

Joe,
I believe there is a 5 volt regulator for control circuitry fed from power input and the 12 volt raw power supply feeds the relay coils. There is also an opto coupler pair that couples the relay control signal into the box.

Re: Multiplex Festo Valves
 

According to the IFI Spike page, this "H-Bridge Relay" is capable of running on 6vdc-16vdc. It sounds like you may have pushed it just a bit too hard.:o

Sorry, no schematic was available on that page.

Re: Multiplex Festo Valves
 

It would make sense that the v-reg fries. IIRC (it was 5 years ago that I took one apart) everything on the PCB is potted up in epoxy, so replacing a component that get's cooked isn't an option.

Re: Multiplex Festo Valves
 

While we're on the topic of silly pneumatics rules, I'd like to direct your attention to this q&a posting.

http://forums.usfirst.org/showthread.php?t=14428

Basically, my understanding of it is that the Festo valve we got in the KOP doesn't meet the requirements of <R72-C>.
But, <R30-A> states that anything that comes in the KOP is legal. So, we are allowed to use the one FESTO Solenoid that came in the KOP, but we can't use more than one of that particular solenoid, since valves in addition to ones provided in the KOP must meet <R72-C>.

Re: Multiplex Festo Valves
 

I think the intention of that rule is to allow the use of duplicates of KOP parts.