GreenAce92

I think its a laser 4ch system and yes the servos are included. Its from servo city.

CrunchyFrog

Very valuable input for my project. Thank you, Doc !

CrunchyFrog

What kind of shielding is available? I was thinking, after I restore the antenna and get my sub performing like before, the next step might be to inhibit RF spikes inside the WTC by putting a toroid core at the leads of the drive motor (the only motor that's inside the WTC), winding both leads the same way at 90 degree intervals around the ring--1 turn at each interval, 4 turns total on the ring.

Currently my batteries are amidships; two power circuits with a common point ground, though the common point is at the external power switch at the WTC's after end ! I wonder how the batteries affect my receiver boards.

It's nice to know, with no recourse against interference on 27MHz and 49MHz, I can probably do whatever I want and not get the FCC interested.

GreenAce92

hey crunch,
hope you dont mind me asking questions on your forum dont want you to think im trying to takeover your forum. (Just in case i was.)

LtDoc

CrunchyFrog ,
I'm sorry if I gave you the impression that you could do anything you wanted to do, that certainly was not my intention. You have constraints, and not staying constrained can certainly make you wish you had - lol. If you are not happy with how your radio systems are working, I think the best advice would be to change to something you would be happy with. Not exactly very 'frugal', but you wouldn't have all the disadvantages you have now. Either way, good luck.
- 'Doc

CrunchyFrog

GreenAce, I'm glad for the participation.

>I'm sorry if I gave you the impression that you could do anything you wanted to do,

Well Doc, I kinda wanted to see what you'd say I guess with any frequency, the FCC will inquire beyond a certain power or range limit.

The frustrating thing about the toroid-ring RF noise suppressors / choke coils is that I can't figure out who would sell them. I know they come on computer cables, like the one I see on my monitor cable. I guess I'll try to make it out to Fry's Electronics or Radio Shack in the next few weeks.

Dub City...they say you get what you pay for, but you'd think design would be competent enough you wouldn't have to get a butter knife to pry the 9V battery out of the transmitter every time you need to charge it. Also, out of the two Dub City cars I've bought, one was DOA at the house--I exchanged it promptly. Thank goodness I test every r/c purchase, every switch, before cutting things open.

CrunchyFrog

This two-board two-frequency design kind of begs the question, doesn't it--what happens if we connect both boards to the same antenna (each board has one antenna terminal?

I don't know, although it doesn't seem to me like a good idea--would the two coils in effect become one coil on a different frequency?

LtDoc

If the coils you are talking about are used as the antenna, then that's at the very least, part of the range problem. Just for 'grins', try adding a section of wire to one end of that coil, that's now your antenna. See what the range is (if any, cuz it also sounds as if that coil is doing something else in the circuit besides being the antenna). If it helps, good. If not, remove it.

Other than economics, I can't think of one good reason for using a two-band radio set up like you are doing. Especially when one of those bands isn't exactly the best for what you are doing. Yeah, I know about costs, but I'm not too sure you're going to be able to 'improve' your set up to the point of usability without more cost than you really want.
- 'Doc

CrunchyFrog

I appreciate your thoughts on this. No, the coil is not being the antenna; there's a separate solder socket on each circuit board for the antenna wire, and my thought was to share an antenna by rigging one antenna with two leads.

I've been doing something akin to your suggestion: My antenna lead has a disconnect a few inches outside the WTC. I'm frequently moving the WTC in or out of the hull, so I've got disconnect plugs on all these wet-servo leads, the power switch, etc.

>I think the best advice would be to change to something you would be happy with. Not exactly very 'frugal', but you wouldn't have all the disadvantages you have now.

Costs were indeed the reason for my being interested in building this way. But I didn't give a thought to how these two systems--one nearly a multiple of the other, as you've commented--might have interactions installed in the same boat. Let's see if I can get even 30-foot surface range of this thing (I just fixed the antenna tonight).

I definitely don't have a lot to spend--and if my boat floods and I just lose it in the lake, I've lost a lot of work but not a $50 Futuba chip, ESC, BEC, and battery pack with it ($100 alltogether?); and not a ballast system costing $100. Finances as they are for now, I think I'll focus on trying to make the cheapest rig. But I'll keep your suggestion in mind in case I drop the constraints (that is, in case finances improve)--a nice Futuba aircraft radio rig, and the power and range that goes with it, should indeed be lots better !

CrunchyFrog

Thinking of your comment that looping the antenna effectively halves it (meaning halving the reception ability?), I cut the new length of wire straight in its under-deck route from stern to conning tower tonight.

It receives continuously from the other side of the house--better than it ever has before.

Thanks !

CrunchyFrog

Ah, love is blind...

My bow planes were disabled this run (I made a power guesstimate, and I wasn't right), plus only my lower rudder moves, the upper rudder I haven't even built a mechanism for yet. Plus I found out my light croaked between last run and now.

But my sub can hear me from across the porch in the kiddie pool now, and this run that's all that mattered !

CrunchyFrog

Toast!

The sub's not responding at all today.

I only ran 15 minutes last night, on a full battery charge. Left it powered down overnight, sitting in its case.

What doesn't make sense is: Signs not much water got in--The WTC was dry last night, had been open all week; I didn't notice the sub riding lower as the session went on, and recovered a teaspoon of water when I opened the WTC 8 hours later. Seems to add up to a lot more leakage than usual, but still not killer.

Signs lots of water got in--a teaspoon drained when I opened the WTC; inside the battery clip and pipe, beads of water. Corrosion spots and rust I don't remember seeing before, but I guess the resulting humidity in the WTC could have done that overnight. Even with batteries replaced, and a customary going-over with the hair dryer--two dead boards.

The meter confirms the power circuit is intact, and batteries are supplying juice.

CrunchyFrog

> Corrosion spots and rust I don't remember seeing before, but I guess the resulting humidity in the WTC could have done that overnight.

Nuts! I remember thinking about putting a packet of de-humidifier in there. I hadn't even given it a thought lately. Oh well--it probably would have soaked up the teaspoon of water, then any additional water still would have humidified the air.

GreenAce92

Wow i thought your sub was doing good.
Hope your sub project works out.

Dont give up mate

CrunchyFrog

Well, thanks. You know there's always the possibility of leaks. Being my first sub design, I didn't appreciate how important it was to be able to check the WTC promptly after every trip (recently, it had been so wonderfully watertight). I can see why many commercial builds allow the whole upper half of the sub to lift off, rather than the "hood" I gave my sub which allows access to insert floats and tend to servo rods and wire, but entails five or ten minutes to take out or insert the WTC.

I might improve the sub's operating method to some degree by installing a drain plug. I always hesitate before making another WTC hole, though...glad I didn't reroute my antenna and make a hole for it this weekend, in fact !

New 49MHz propulsion board for the sub when finances allow. For the bow planes, I can probably scrounge a board from my stockpile of half-functional boards.

subhunter13

Tell me when you get all the bugs worked out

CrunchyFrog

That'll never be. You might want to get a nice Wally boat or SubTech model in the meantime. I'm not going commercial with a raft of secondhand boards and sealant goop.

CrunchyFrog

Ah! Back to cruising speed. One of the boards I'd put away from another job as scrap was still 100% functioning. It's the same frequency as the bow-planes board, which means I can't operate bow planes until I replace the bow-planes board with a different frequency, but the sub's working again.

I tried converting a board to the desired frequency--that is, I took the coil from a nonworking board of the desired frequency and soldered it to a half-working working board I keep for testing that, until then, had been a different frequency. It didn't work--probably because the coil is only half of the "tank circuit" G4dude described. So maybe to change a board to another frequency, not only the coil but also the capacitance would have to be changed.

CrunchyFrog

Wikipedia has this formula under "tank circuit":

f frequency in hertz = 1/ ( 2 * pi * (square root of (L * C) ) )

Where L is inductance in henries, C capacitance in farads.



So to keep the same frequency assuming I had doubled L, to keep the same L * C product in the equation I would have had to have halved C.

Or alternatively, if I'd halved L, I would have needed to double C.

(Too intricate. I'll just buy a $15 board for those bow planes).

GreenAce92

I agree. Too many variables.

Captain Nemo12

Crunchy, did you replace the coil or the receiver crystal? The crystal is a thin, metal-can with the frequency written on it, perhaps replacing that will work.

CrunchyFrog

It's a coil. Now you've got me really curious, though, how crystal circuits are different from coil-based circuits.

Captain Nemo12

I'm not sure, most of the circuits I've worked on had a receiver/transmiter crystal. The crystal must be acting like a signal oscillator that regulates the current through the coil.

CrunchyFrog

You win some, you lose some...

I was wrong about my sub being back in action: As I started testing prior to an anticipated pool session, I wasn't always able to coax a response--so the intended replacement goes back to the scrap pile.

Whatever sapped my propulsion board killed it pretty dead. On the other hand, the bow-planes board I'd given up on revived on its own.

CrunchyFrog

Rebuilt...pristine propulsion card...ready for testing.

I haven't had much success with hot glue before, but I'll give it one more especially diligent try.

Hot-glue sealing would be desirable as a best practice: I'm wanting to open and then reseal the WTC frequently, and hot glue becomes set in a minute or two depending on how much material I dispense into one space.

If I can't get hot glue to make an effective seal, I'll revert to GE Silicone II by the weekend.