Clippard valve and RCABS questions

[petn7]

Do Clippard valves, such as those sold by Mike's Subworks, have a wide range of operating voltages? I notice there are 6v and 12v clippard valves, but would a 12v clippard valve work off 8.4v? Or how about the 6v clippard working off 8.4v? Would either work? If so, what's better, give too little voltage or too much voltage to a clippard valve?

When using RCABS with 1 pump and 1 clippard (or shrader) valve, in order to dive, the clippard/shrader valve must be activated, right? But wouldn't there still be some air in the bladder? I know that some have the bladder on the outside of the WTC with rubber bands to squeeze out some of the air, but what about if the bladder is in the WTC? The reason I ask is that I have the bladder inside the WTC. I planned on using a second pump to suck out the remaining air, but so far, the Caswell pump that's to be used for this purpose can't hold the air in the bladder under high enough pressure while maintaining the vacuum in the WTC. It seems like a clippard valve is the only option, but I want to somehow be able to remove all the air from the bladder to dive, since I'm already using an undersized ballast tank.

[Guest]

RCABS questions

In the RCABS, there is no reason to run the bladder in the WTC. If you mean to run it in a perforated tank isolated from the watertight compartments, that is OK. If the watertight compartments are not leaking, the inflated bladder will deflate when the tire valve or Clippard valve is activated. The partial vacuum created in the WTC completely deflates the bladder, with or without the rubber bands. If the WTC is not air tight, the bladder might not deflate quickly or completely, but that would not be your only problem. You do not need to pump air out of the inflated bladder in the RCABS.
I don't know about the voltage question on the Clippard valves, but the safest way to protect the valve and sub would be to see if the 12V model will activate with an almost discharged battery of your voltage choice.
I run the 6V Smart Products air pump on all voltages from 6 to 12V with no problems yet.

[petn7]

Re: RCABS questions

My bladder is in a "perforated tank." Looks like I'll buy a clippard valve as you say there should be no air left over in the bladder.

I'll wait to hopefully get more responses regarding which clippard valve I should buy (they're expensive!).

[JWLaRue]

Hi Curtis,

...please remind me what

Hi Curtis,

...please remind me what battery pack voltage you are using....I'm going to assume it's not a 12-volt pack for now.

The Clippard model number ET-2-6-H is for systems running off 6 volts. However......the Clippard web site indicates that their 6-volt model can run off a voltage input range of 5.4 to 9 volts. (The ET-2-12-H would work best for a system powered with a 12-volt battery pack and can tolerate input voltages from 10.8 to 18 volts)

Since these things are built like brick outhouses, I'd say that the web site telling us that a slight over voltage is okay and wouldn't hurt them means that you'd be safe with the 6-volt model unless you are running a 12-volt battery pack.

Of course, you could contact Clippard for pricing for a unit built for a different voltage supply value. (per their web site).

-Jeff

[petn7]

Hi Jeff,

I am currently planning

Hi Jeff,

I am currently planning on using a 7 cell, AA NiMH battery pack using Eneloop cells. I could go down to a 6 cell battery pack, but only if I have enough juice for the main drive motor; I will do speed tests later. Hot off the charger, 7 cells should give over 9 volts. Of course, I could make a note to let the battery pack "settle" before using it in my sub.

I think I might have better odds for success with the 6v version rather than the 12v. Looks like I'll give Mike a call soon.

Edit: I just spoke with Mike and he recommended the 6V clippard valve. He even said he's used the 6v valve with a 7 cell NiMH battery no problem. I may end up downgrading to 6 cells anyways to be safe.

[JWLaRue]

Makes sense......that 9.4 volt pack

Makes sense......that 9.4 volt pack won't be at that level for very long.....

-Jeff

[crazy ivan]

Curtis,

The 7 cells shouldn't be

Curtis,

The 7 cells shouldn't be a problem for the short amount of time you need to turn the Clippard valve on, but If you are worried about it there are a couple of other things you can do to reduce the voltage a bit and still retain the 7 cells for your drive motor. One is to tap your battery pack at the 6th cell just to feed the valve. The small drain from the valve for such short periods should not noticeably unbalance the charge on the pack.

The other thing would be to run everything off the 7 cells, but put 2 or 3 diodes in series with the valve. This will drop the voltage down enough to take the "edge" off a full charged pack.

[petn7]

The diodes are a good

The diodes are a good idea. If 6 cells don't work and I MUST use 7, I'll try your suggestion.

[petn7]

By the way, I assume

By the way, I assume I don't have to worry about polarity with Clippard valves?

[bigdave]

There is no polarity on

There is no polarity on the valves. But make sure you have the polarity correct on the diode that should be used across the valve to stop the electrical spike. BD.

[petn7]

Thanks Dave

Thanks Dave

[don prince]

Hi BigDave,

Please excuse my lack

Hi BigDave,

Please excuse my lack of knowledge.... Quiestion: could you use a capacitor across the Clippard Valve to eliminate an electrical spike? This would be similar to CAPs used acress the drive motor power connections.

Regards,
Don_

[petn7]

Is the wire coming from

Is the wire coming from the end of the diode with the silver ring the positive end?

[crazy ivan]

Curtis,

The band on a diode

Curtis,

The band on a diode indicates the cathode, (negative) end.

Don,

A diode does a much better job of suppressing transients when switching an inductive load like a valve or a relay. When power to such a load is cut off, a huge high voltage spike of the opposite polarity (back EMF) is generated (much like the points and spark coil ignition systems in cars of old) which can and will destroy the typical transistor or FET you might be using to drive it. A diode connected across your coil in reverse polarity will short out the spike at its source and protect the solid state switching device. This is standard electrical practice. Sometimes a capacitor is added as well. Of course, if you are using a mechanical switch to control your valve, its not such a big deal. But still a good idea as it will keep the switch contacts from arcing and burning.

The capacitors used on a drive motor are there more to suppress interference to your receiver (RFI). We can't use diodes here because they would short out your ESC when you went into reverse. I do, however put a reverse diode across the motors of my RCABS air pumps, as they only run in one direction. Hope that explains it.

[petn7]

I was reading some older

I was reading some older SCR issues and came across the RFI suppression article, which has led to some questions.

When I bought the SES-3, it came with what appears to be a diode. I think it's a 1N4001 or IN4001 diode. The instructions recommended using this on motors only (didn't indicate this was necessary for solenoids, for example). I presume I should use a diode on the air pump motor AND the Clippard valve? If so, what do I buy? I was looking for a 9V "transient voltage suppressor" on the Radio Shack website, but only see diodes rated by amps and "PIV." I did find "1N4001" micro diodes that appear to be what came with the SES-3. Is this what I should use with a 6 or 7 cell NiMH battery pack?

Also, the SES-3 instructions said the wire with the silver band should actually be attached to the air pump motor terminal that gets the POSITIVE wire from the battery. This seems to be the opposite of what has been said in this thread. Are the SES-3 instructions wrong? The SCR article mentioned nothing about polarity with regards to "transient voltage suppressors" which I presume are synonymous with diodes.