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Old Jan 11, 2013, 06:10 AM
John
Australia, QLD, Brisbane
Joined Aug 2012
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Originally Posted by slothy89 View Post
See if you can hook something up to the Camera port on the PCB and use the button on the TX to turn it on and off?
Guess it'd be pretty easy to rig something that would have the camera button run the camera if the main rotor was turning, or the sonalert (piezo buzzer) if it wasn't - after (say) a 10 sec delay. A starting point, anyway Slothy. Might try this.

Edit - Come to think of it, you could make yourself pretty unpopular hanging this over someone's backyard with the camera button linked directly to a 100db car reversing alarm, say. Fun for all! (of course, the Yanks would have their 'second amendment solution' to this)
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Old Jan 11, 2013, 06:58 AM
Scotsman in Germany
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Germany, BY, Schwabach
Joined Oct 2012
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Originally Posted by BobTopofTheWorld View Post
All this talk of undervoltage indicators got me thinking... whats all the fuss over, we are talking like 6-7 parts, only 1 is a 'centipede' and the rest can be built on the IC. Is adjustable and will drive a LED AND a piezo 'annoyance device'.
Ok for the specifics:
LM 741 op amp (8 pin dip plastic case is best)
100,000 ohm mini potentiometer
27k 1/2 watt resistor
few assorted resistors from 500 ohm to 2.2 k 1/2 watt (to dial in the piezo)
LED
5.1 volt 1/2 watt zener diode (anything from 4.2 to 5.1 volt will work)
Piezoelectric beeper (micro is good)

Following the diagram, it is a quite simple task to build it right between the legs of the centipede. The IC is tough so dont worry too much about static (MOS devices are REAL static sensative, this isnt one of them). As to the piezo, it attaches to the + rail and to pin 6 of the IC through the 500 or so ohm resistor (selected by you for best beeper annoyance) and can straddle the IC too.
OK to calibrate the beastie: with a reliable voltmeter connected, discharge a battery (or connect a calibrated source) to the point you wish to be warned, 6.4 volts as I recall (3.2 v per cell) and carefully adjust the 100k pot until it yelps/lights the led. Lower the discharge rate (raising the voltage) and verify the alarm stops, and again raise discharge to lower the voltage to alarm level, fine tuning as reqd. As this is a simple comparator, once set properly it wont require resetting (unless you change the battery voltage).
After it is set properly, one can simply cover the whole ic with a suitable glob of silicon sealant, or mount on a suitable insulated non-metalic surface as desired. Of course dont fill the piezo's output 'hole' with silicone, that kinda defeats its purpose.
I believe the monitoring of a single cell in a multiple cell battery is ignorant. What if the cell thats not monitor'd decides to droop? The 3.2 v warning device WONT DO YOU ANY GOOD in such a situation (and I bet its nawt long before we hear about it). Set up the alarm to read the full voltage, then if any one cell gets grumpy , the alarm circuit will act as intended.
Let me know if you lot like my style, I got plenty of ideas, and it has been a long time since I taught univ level electronics.
Cheers lads
Quote:
Originally Posted by rexless View Post
I don't know nearly enough about electronics to understand how that works but I could probably assemble from your diagram if I knew where to buy parts.
rexless, I'll take this one up (or down ) a level...

Bob!! You're the very man I've been looking for!!

Think you could explain to me why the electricity doesn't fall out of the wall socket when I pull the plug??

Only HALF kidding . Give me something mechanical in my hands and a bit of time, and I've a fair chance of figuring out how it works. Give me something electrical, and you'd better give me an electrician along with it .
My dad was a spark to trade, but I reckon all that rubbed off on me was the static .
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Old Jan 11, 2013, 07:10 AM
Brent 黑雁
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Canada, AB, Ponoka
Joined Jan 2012
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Originally Posted by arrowshooter View Post
Actually, it is a Walkera 4ch system with 3 axis gyro. More interested in the tail servo capability than I am the gyro right now, but the gyro will come into play when I wack off the flybar and put a 90 deg swashplate on'er.
You guys may have issues running a belt driven tail because the tail speed will be way too low. A good example is a 250 Heli. When the head speed is too low, tail twitch occurs and loss of tail authority. In this case, your tail speed will be half of a standard 450. Using a 3 or 4 blade tail rotor might help if this problem occurs.
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Old Jan 11, 2013, 07:58 AM
John
Australia, QLD, Brisbane
Joined Aug 2012
542 Posts
BobTopofTheWorld -
As I linked, there are pretty darn good voltmeters/alarms available now for helis, testing cells both individually and collectively, available at $2 to $5.
The really pressing electronic need (imo) at the moment is a more efficient and reliable brushed to BL converter for the tail rotor: consists of adapting the variable c. 2kHz PWM tail drive signal (check it on your scope, or my previous posts) to a standard (fixed prf) servo/ESC drive. I'm about half way through the project, but it's a lot longer since I taught/ earned a living in electronics, and maybe you could come up with a new approach/working solution a bit quicker.
This need arises because every keen F45 owner can reasonably easily convert his main motor to BL (you should too, it's a vast improvement). But he'll still need a pile of spare tail rotors and/or gears, as they will fail - often unpredictably - between every 30 and 80 flights. Sounds a lot, but at 5 flights a day a motor will only last a week or so.
The only commercial product AFIK (even modified) is increasingly unavailable, and not altogether ideal. So a definite need IS there.
And I'll not be able to devote much time to it when I restart full time work next week (PC repairs these days). So, if you were looking for a challenge...!
Cheers
John
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Old Jan 11, 2013, 08:15 AM
John
Australia, QLD, Brisbane
Joined Aug 2012
542 Posts
Quote:
Originally Posted by BThirsk View Post
You guys may have issues running a belt driven tail because the tail speed will be way too low. A good example is a 250 Heli. When the head speed is too low, tail twitch occurs and loss of tail authority. In this case, your tail speed will be half of a standard 450. Using a 3 or 4 blade tail rotor might help if this problem occurs.
I did try it, using a standard (variable pitch) 450 tail and F45 Rx: it did work, but (I agree) not very well. Perhaps for the reasons you've given
As above, still working on a better BL conversion first: though my present system is pretty good, have to admit it's still not quite as good as the brushed tail.
However, mine worked a lot better with belt tail using my 6ch Tx/Rx/gyro. Perhaps Rexless' idea using 5deg? funcopter blades will also necessitate him getting the headspeed up as you advise. Certainly got to be interesting seeing how his FBL conversion goes.
Regards
John.
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Old Jan 11, 2013, 04:06 PM
Scotsman in Germany
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Germany, BY, Schwabach
Joined Oct 2012
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first aerial vid

Spent some of my spare time after work constructively today

Fixed the 808 camera under my F45, flew a couple of batteries - was a bit on the windy side, but who cares - then came home, downloaded some video editing software and started trying to learn how to use it. Not going to win any prizes, but at least the music's good. My guitar playing wasn't too hot after a week or so either . Need to tilt the camera just a shade more to get the helis nose out of the frame as well, but that's all just trial and error .

Since it's the free version there's a watermark on the vid, but 8 helis within the last 2 months or so, plus spare parts, plus accessories has kind of eaten away at my "hobby budget" for the time being . No matter; it gives me something to practice on in the meantime - and I can try out various trial versions to see which I prefer - and once the coffers have been replenished I'll no doubt get a #16 808 and see about buying a licence for the software. Then the sky's the limit .

Most of the vid is hovering and gentle messing about, but the best bit right at the end somehow got missed. The camera was still recording audio for about the last 5 or 6 minutes, but the video footage just stuck on the one picture . Anybody else had this problem with the cheapo 808 cameras? If so, know if there's a fix for it, or do I just have to live with the possibility of it happening til I buy a better one?

Good weekend guys, and Happy Flying.
Fin

Fin's MJX F45 first aerial vid.wmv (6 min 27 sec)
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Old Jan 11, 2013, 08:01 PM
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Originally Posted by hawaiichopper View Post
You will feel racheting in both gear sets. This is normal. They will not be "free wheeling" like the V911. I have a little smaller Solo Pro 228 that has the same feel. My little choppers are all "free wheeling".
Yep, I figured that out, Allen. And the gearsets loosened just a bit with the first flight. The 2200 ma LiPo i got from techntoys was excellent. It fits right in the stock battery box (with no trimming tabs) and sliding it foward to the stop made the chopper balance perfect. (and is 16 gm lighter than the stock one) I get 9 min flights and am not even close to max discharge levels. 2+ hours to charge isnt so much fun for this hardcore addict... perhaps a fancy charger is in my future.
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Old Jan 11, 2013, 09:01 PM
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Originally Posted by hawaiichopper View Post
Glad to hear all went well! As mentioned, try to keep the flights to 7-8 minutes (unless it's cold). Heat will significantly shorten the lives of the stock motors. They can get to 140 degrees F or more. BTW, sent you a PM about the F45.
It hasnt been above 32f (0c) here, and but for the cheapo landing struts, the copter loves it. I checked the motor temp after 5 min, barely warm... after 8 min, warm... after 9-10 min it is just getting hot enough I can touch it and tell its been used. Thats with my home-brew'd catfood can heatsink.
I got a probe style thermo I think I will adapt to the copter, as in install the thermister on the motor case so I can get some real data about 'rate of rise' and 'peak temp' ect. I am betting the low outdoor temps are helping, as I have just as much power after 8 min as I have starting.
Again I dont fly like a 'bat outta hell', I putt around. The brushless mod isnt on my 'gotta have' list quite yet.
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Old Jan 11, 2013, 09:21 PM
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ByGolly Rex you have an excellent idea there. Come to think on it, a 'locator' would be a valued asset to any flying craft. I will get to researching this. The parts can be had at any decent RadioShack... hmmm yur in Canukland, I dunno there. Call around and find whom carries 'electronic components'. All the parts retail isnt 5 usd. The IC pinout starts at the dot (or indention) as pin 1 and clockwise around to pin 8 (across from pin 1) (in other words pin 1 & 8 are on one end, 4 & 5 on the other end). The pin spacing is perfect for 1/2 watt parts.
As to soldering, its easy... CLEAN THE CONNECTIONS, use the right amount of heat, tin the soldering iron tip properly... and you are fully permitted to practice on scrap wire, old circuit boards ect. The old saying 'practice makes perfect' works here.
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Old Jan 11, 2013, 09:33 PM
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Originally Posted by OldOz View Post
You know Bob, I never thought of the advantages of snow - guess it would make at least a softer landing spot than the baked hard football field I use up here. If you didn't bury the heli completely, I guess.
But I think I'll not find out any time soon: has never snowed in Brisbane, but very occasionally we might get a light frost in winter where I live lol. Still vivid memories of my time in Canada, though - straight from here to work in Calgary midwinter. Memorable!
John, my mate in Midura keeps me up on the conditions in his neck of the woods... I dunno how you lot stand the brutal heat... 45c??? And he wonders how I stand -20c LOL. it is a 'dry cold' The humidity is quite low, so one can dress for the climate, in layers. I was out today in -5c for quite a while, only my ears got cold.
And yes the snow has a cushioning effect... however there is that other consideration, ICE. LOL Believe me, ice is every bit as hard as a packed/parched ground. Seen the little lady's arse bounce on it today... me thinks it is still hard (the ice) LMAO
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Old Jan 11, 2013, 09:49 PM
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Originally Posted by slothy89 View Post
See if you can hook something up to the Camera port on the PCB and use the button on the TX to turn it on and off?
OMG Slothy I do believe you have solved the issue.
Firstly, lads dont plug more than a LED sized load into this port, give me a tic to look at it and report how much current is available. (unless you got another rx board that you just gotta install)
Right away I didnt see the camera plug connected to the wee transistor, I will look into this for sure. Thinking a driver transistor (to isolate input and switch more current) and a piezo will solve this.
More soon
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Old Jan 11, 2013, 09:52 PM
John
Australia, QLD, Brisbane
Joined Aug 2012
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Quote:
Originally Posted by BobTopofTheWorld View Post
John, my mate in Midura keeps me up on the conditions in his neck of the woods... I dunno how you lot stand the brutal heat... 45c??? And he wonders how I stand -20c LOL. it is a 'dry cold' The humidity is quite low, so one can dress for the climate, in layers. I was out today in -5c for quite a while, only my ears got cold.
And yes the snow has a cushioning effect... however there is that other consideration, ICE. LOL Believe me, ice is every bit as hard as a packed/parched ground. Seen the little lady's arse bounce on it today... me thinks it is still hard (the ice) LMAO
I guess it's all what you get used to, Bob. Hasn't been over 39 here yet, but the humidity is the killer up in Brisbane (or was before A/c). OK for flying at 5am usually, though.
Start working on that radiolocation idea! (would really like to see a 'beacon' and RDF like real aircraft, sound alone wouldn't have helped this time) - lost my 2nd heli in 9 months this morning (again, RIP). Of course it would be the one with the fully BL tail: still, have a fair few people looking for it, and a $50 reward out. My own silly fault, pushing the boundaries again - lost orientation 80/100m away.

Hope your wife recovers! and yeah, remember how hard that 'ice' stuff was myself. Also keeping trucks running 24/7 (or needing a fire under the sump to restart). But good to know AK climate's keeping your motors cool
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Old Jan 11, 2013, 10:08 PM
Hangin' for a strong SW
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Australia, VIC, Sebastopol
Joined Apr 2012
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Quote:
Originally Posted by BobTopofTheWorld View Post
OMG Slothy I do believe you have solved the issue.
Firstly, lads dont plug more than a LED sized load into this port, give me a tic to look at it and report how much current is available. (unless you got another rx board that you just gotta install)
Right away I didnt see the camera plug connected to the wee transistor, I will look into this for sure. Thinking a driver transistor (to isolate input and switch more current) and a piezo will solve this.
More soon
even if you just use the signal and ground pins and get your power source from somewhere else to allow a greater load, it will give a fairly simple method of adding the on/off functionality to the stock F45
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Old Jan 11, 2013, 11:12 PM
John
Australia, QLD, Brisbane
Joined Aug 2012
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Crash location -
Hmm - some 'pet locators' look promising: as does a triggered low power omnidirectional LW signal and a rod antenna Rx. I'm NOT going to get caught this way again!
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Old Jan 11, 2013, 11:37 PM
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I gotta post this one... while doing my shopping/bill paying, ran across this wee kiosch in the mall selling r/c copters... coaxial f45 size with CHEAPO 27 meg tx... 300 usd. After 4 min of laughing, he said 'i sell to you for $150'... passed by after a stroll to the ice exhibits, had to chuckle, again, 'i sell to you for $100 '... Fellows we talking the worst china models I ever seen. Did i mention the 450 class coaxial for 600 usd?
(why on earth would they make a coaxial that big) OOOOOOH I know why, so i can take a wee nap while flying LMAO, it is so docile i bet i could
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