FM Receiver outputs - How does it work???

[don prince]

[color=#000000]Gentlemen,

I have been reading up on the basic electronic characteristics on the R/C transmitter and receiver. Basically here is what I understand. A pulse for each channel is transmitted every 20 ms. The 20 ms envelope will contain a pulse for each channel that the radio has available. For example if channel 1 is transmitting to a servo device then]

[skip asay]

Don -
The TX sends pulse

Don -
The TX sends pulse "trains" to the RX at a "frame rate" of approximately 20mS. Each "train" consists of a start pulse (heads up to the RX that another set of pulses is coming) followed by a pulse for each channel. The width of each channel pulse is determined by the stick (pot) position of each channel on the TX which is usually between 1.0 - 2.0mS. The "train" ends with a "stop" pulse.
Usually, a 3 position switch is electronically configured to create a pulse width of 1.0mS, 1.5mS, 2.0mS. Please note that the 1.0 and 2.0mS numbers are nominal and can vary from radio to radio but they'll be close to those numbers.
Now, the real question is, exactly what will the RX be controlling? Solenoids? Servos?
If solenoids, then the RX can control a switch similar to the SubTech SES-II Dual Function Switch. If 2 separate servos, each can be mechanically configured to do its job separately from the other.
If the RX will be controlling a microcomputer which will then operate your ballast system, the micro can be programmed to accept only the desired pulse widths for each operation.

Skip Asay
SubTech

[don prince]

Hi Skip,

Thanks for the quick

[color=#000000]Hi Skip,

Thanks for the quick response.... I understand the TX is using a T0 through Tn a 100us which will define the channel pulse at the receiver. Your SES-II sounds like it will do the trick.

Question]

[skip asay]

Don -

The SES-II was originally

Don -

The SES-II was originally designed specifically for gas (Freon/CO2/Propel) ballast system control.

Each output can be configured for either latching (lights, radar, etc.) or momentary (ballast system, horn, etc.) by selecting a jumper position. Optimum ballast system operation calls for momentary, however, and should be used with a 3 position switch with the center position being off (1.5mS). BTW - I recommend that if that switch on the TX is not self centering you replace it with one that is. The chances of forgetting to return it to center when surfacing will shorten the number of blows considerably! And yes, when the jumpers are in the momentary position, you can "blip" the switch to partially fill/empty the ballast tank.

The failsafe will operate either output (user selected jumper) and works on a missing pulse principle. Failsafe will turn off when signal is re-acquired.

Both APC-3 and APC-4 allow you to override from the TX so you can help the dive operation. Personally, I prefer to make use of the fact that either of these can "stand alone" (no signal input) when the boat has bow planes since it becomes real easy to over compensate and bring the prop out of the water when diving. That also frees up another channel. I use a 4 channel radio in my Albacore and Marlin, each of which has a full hybrid ballast system (pump w/propel back up) as well as an ADC-1 Depth control which I can turn on/off from the TX. An SES-II is used for toggling the Depth Control as well as controlling the Propel for emergency ballast blow. To control the stern planes as well would require another channel. It's a set up that works very well!

Please note that APC-3 is no longer in production.

Skip Asay
SubTech

[don prince]

Hi Skip,

I really appreciaty your

Hi Skip,

I really appreciaty your advice.... I believe The SES-II will work for my ballast system. I plan on using a sealed tank with a Surflo bi-directional pump and a Solenoid valve. The pump will flood the tank to 60% and a pressure switch will stop the pump.

I designed the gated circuitry so a pressure switch will stop the pump/tank fill (Dive) sequence. I also set up a gate to disable the dive sequence if the power is low.

When it comes time to surface (by command, or missing pulse, or power low) the pump will evacuate the water from the tank (helped by the pressurized force as well). The tank has two baffels, and three bottom inlet areas (front, center, and back). Each inlet has a float that will seal the inlet, and a matching sensor. When any two sensors are activated (Float closed), the circuitry will de-activate the pump surface sequence.

I will not be using a return to center toggle switch. I want the tank to be purged when my U-boat is on the surface. The U-boat will be level, and if there is any water in the tank it will automatically be removed if any two floats don't stay down (sealed).

I'm still working on my dive/surface assist circuitry... I think I've got it worked out. However, right now everything is on paper, and nothing has been hardware tested yet.

What is your opinion of a sealed pressurized ballast tank system? The one advantage that I see, there is no need to refill a gas tank.

Regards,
Don_

[skip asay]

Hi Don -

You asked -
“What

Hi Don -

You asked -
“What is your opinion of a sealed pressurized ballast tank system? The one advantage that I see, there is no need to refill a gas tank.”

Right from the beginning, let me get this on the table. I am absolutely a believer in the KISS Principle. In terms of a ballast system, it must have as few moving parts as possible, be simple to understand, easily maintained, consistently reliable, etc. That also means that the tank itself should be hard, not flexible, since flexibility means that you’ll get a different amount of water in the tank each time you fill it. I don’t like the idea of “tweaking” the ballast every time I dive.

Will your design work? Certainly. And probably work well. With a considerable amount of R&D. But with enough R&D, virtually any system can be made to work. But there’s the rub - R&D. Among other things, R&D = TIME. You can also read that as trial and error which invariably means heavy on the error part.

Would I build a system like this for 1 of my boats? Not hardly. Been there, done that, won’t go back. Too many negatives. After many years of “R&D” (more than 30! ####! Wasn’t it just last month that I put my first boat in the water?), I’ve settled on the “Hybrid” system which I feel uses the best parts of pump systems and gas systems but eliminates the drawbacks of each. A high volume/low current pump fills/empties the ballast tank at a speed approximating a realistic looking dive/surface without any substantial drain on the battery. And with onboard gas, surfacing after wrapping weeds or fishing line around the prop is as simple as it would be with a purely gas system. And for those guys concerned with the high cost of Propel, a couple of strokes from a bicycle tire pump gives the same result. While I never run my boats with less than a full load of Propel, I seldom need/use it.

Don, I’m sorry if I rained on your parade but you did ask for my opinion.

Skip Asay
SubTech

[JWLaRue]

...not to rain on Skip's

...not to rain on Skip's parade....

...but the system that you are describing Don is exactly what is being sold by OTW. It works and it works just fine. It's nice to not have to worry about a change in the boat's trim every time you use a bit of Propel to empty the ballast tank....and on a boat the size of your 1/32nd Type VII, that's a lot of Propel weight!

-Jeff

[skip asay]

"It's nice to not have

"It's nice to not have to worry about a change in the boat's trim every time you use a bit of Propel to empty the ballast tank...."

As is true for the Hybrid system. The Propel (or compressed air) is only there for failsafe purposes.

What rain?

Skip Asay
SubTech



Edited By Skip Asay on 1080342109

[JWLaRue]

Skip,

Agreed. However, not everyone is

Skip,

Agreed. However, not everyone is comfortable with having to rely on driving the boat to the surface in order to be ale to empty the ballast tank.

It's just a matter of individual preference.

-Jeff

[Larry Kuntz]

I had a long discussion

I had a long discussion on the phone with Skip on the pros and cons of the different systems. I hadn’t noticed the thread in this forum until he pointed it out to me. I’m building my first sub, the Dumas Akula, and have seen and run Crazy Ivan’s as a dynamic diver. BigDave is also in the midst of changing his Akula as is Ivan. I waited a bit to see how these systems function, but am now working on the bladder method. I’m amazed at the number of methods and the slight variations of each. As I told Skip, half of my fun has been the R&D part of pump volumes, bladder sizes, and valve types (to deflate the bladder). Doing the rough calculations of displacement and the times needed to inflate and deflate. Hopefully I’m close to a final setup, but what the heck, changes and adjustments are part of the fun for me.