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Old Jan 10, 2013, 10:17 PM
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United States, OR, Portland
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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.
THAT would be really nice!
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Old Jan 10, 2013, 10:22 PM
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United States, OR, Portland
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Originally Posted by BobTopofTheWorld View Post
OK some of the mystery as to why She went for the second F45... I heard this uttered under her breath "cause you're a grumpy old fk when you wait a month for parts"... :O:|:O
Did I bh... when She got one of them useless nooks??? (OH did I mention that I was expected to 'sort it right away') oh ok i best shut up... Anyway thanks goes out to hawaiichopper for that deal.
Carry on
Glad the deal was done and you're happy. You get a pristine chopper and I can hit the Buy Button on another "100" size to fly through the jungle here. Rotten trees - heli magnets they are.
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Old Jan 10, 2013, 10:27 PM
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Originally Posted by mckoyman View Post
what are some of unknown issues of mjx f45
This thread is pretty complete. I think any issues have been presented, and there are only a few. Much less than found on a number of other choppers that take a bunch of mods and/or break parts rather easily. If I didn't move to a house with a smaller yard with more trees, I would never have sold the F45. Still got a red one for sale - excellent condition.
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Old Jan 10, 2013, 11:57 PM
John
Australia, QLD, Brisbane
Joined Aug 2012
542 Posts
Tend to agree with you, hawaiichopper - in part.
Anyone who cares to read the thread will certainly find any issues pertaining to the stock F45 discussed as comprehensively as they would wish.
However, the mods roll on. E.g., Arrowshooters FBL F45, the 45/450, BL tail mods, new series PCA - there's still plenty of scope for (and imo interest in) contributors reports and ideas.
Or we wouldn't be getting the pageviews we are!
Am sure you'll sell your F45 in time. Probably buy it myself if living in US: still miss the one that flew away (RIP).
Cheers
John.
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Old Jan 11, 2013, 12:57 AM
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McKoyman the weak points with the F45 are: the cheapo brushed motors, rx only binds to the MJX tx, tx is mushy at the stick midpoint, no fancy computer mixing, stock battery is NOT Li-po as advertized, slow to respond in any decent wind... fellows did I miss anything?
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Old Jan 11, 2013, 01:03 AM
Fly Fast, Fly Hard, Fly Fun
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Canada, BC
Joined Apr 2012
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Current versions need a mod to fix loop breakages. Landing skids are weak.

And most of the issues have fairly inexpensive replacements or easy mods/upgrades!
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Old Jan 11, 2013, 01:46 AM
John
Australia, QLD, Brisbane
Joined Aug 2012
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Still think most neccessary mods listed on p194. However, agree landing skids could also do with aluminum coathanger wire shoved up each one.
THEN, by all means, BL main and so forth .
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Old Jan 11, 2013, 01:50 AM
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cheapo 7.2 volt under-voltage indicator

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
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Old Jan 11, 2013, 01:58 AM
John
Australia, QLD, Brisbane
Joined Aug 2012
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- or buy the HK battery monitor, checks each cell in turn, then total voltage. Around $3. Got one on all my helis.
http://www.hobbyking.com/hobbyking/s...itor_2_6S.html
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Old Jan 11, 2013, 02:11 AM
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Quote:
Originally Posted by rexless View Post
Current versions need a mod to fix loop breakages. Landing skids are weak.

And most of the issues have fairly inexpensive replacements or easy mods/upgrades!
LOL I am just doing the dogbone guide mod... thanks for the addition John.
And yea wot Rex said too.
Spares are getting more plentiful daily.
Still all in all, the F45 is a sweet, inexpensive, hardy copter to simply GO HAVE FUN FLYING. The basic mods will only make it more fun, I flew mine before and after doing the horn swap, shimming blade grips ect. Most helpful was blade grip shims and (of course) the main blades were not equal in weight. Even the blade weight problem needed no 'send for more' parts, I took out the extra blades and weighed them. One was a perfect match.
So sweet, I bought another F45
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Old Jan 11, 2013, 02:32 AM
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Originally Posted by hawaiichopper View Post
Glad the deal was done and you're happy. You get a pristine chopper and I can hit the Buy Button on another "100" size to fly through the jungle here. Rotten trees - heli magnets they are.
LMAO yea they are... dont forget them 'invisable' chain-link fences... I landed on top of one tonight... (yes I said landed on top of a chainlink fence) It was fine til I shut down the throttle, then it fell on the other side of the fence. Not to worry, it wasnt the 12', only an 8'. Thank **** for the snow berm... and GUESS WOT......................... NO DAMAGE, not even the flybar was off center. I love this copter... cant wait for my am flight. Gonna sign off for now
Cheers lads
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Old Jan 11, 2013, 02:41 AM
Fly Fast, Fly Hard, Fly Fun
rexless's Avatar
Canada, BC
Joined Apr 2012
1,501 Posts
Quote:
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
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. Personally I haven't found I need a low voltage sensor on the f45 as it seems to notify me through performance characteristics. What I'm looking for is a simple locator with a remote trigger so I can easily find my helicopter next time I lose one. Most of the solutions are based on Rx/Tx signals and send audio but don't have a solution for cases where you say get stuck on a neighbors roof and want to shut it up until you can arrange extraction.
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Old Jan 11, 2013, 02:55 AM
John
Australia, QLD, Brisbane
Joined Aug 2012
542 Posts
Quote:
Originally Posted by BobTopofTheWorld View Post
LMAO yea they are... dont forget them 'invisable' chain-link fences... I landed on top of one tonight... (yes I said landed on top of a chainlink fence) It was fine til I shut down the throttle, then it fell on the other side of the fence. Not to worry, it wasnt the 12', only an 8'. Thank **** for the snow berm... and GUESS WOT......................... NO DAMAGE, not even the flybar was off center. I love this copter... cant wait for my am flight. Gonna sign off for now
Cheers lads
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!
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Old Jan 11, 2013, 02:59 AM
John
Australia, QLD, Brisbane
Joined Aug 2012
542 Posts
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. Personally I haven't found I need a low voltage sensor on the f45 as it seems to notify me through performance characteristics. What I'm looking for is a simple locator with a remote trigger so I can easily find my helicopter next time I lose one. Most of the solutions are based on Rx/Tx signals and send audio but don't have a solution for cases where you say get stuck on a neighbors roof and want to shut it up until you can arrange extraction.
When you find an answer, let me know too, Rexless!
Only thing I could think of was FPV (which was my next step if I hadn't gone CP instead). There's got to be some kind of beacon/locator out there?
Cheers
John
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Old Jan 11, 2013, 05:38 AM
Hangin' for a strong SW
slothy89's Avatar
Australia, VIC, Sebastopol
Joined Apr 2012
770 Posts
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. Personally I haven't found I need a low voltage sensor on the f45 as it seems to notify me through performance characteristics. What I'm looking for is a simple locator with a remote trigger so I can easily find my helicopter next time I lose one. Most of the solutions are based on Rx/Tx signals and send audio but don't have a solution for cases where you say get stuck on a neighbors roof and want to shut it up until you can arrange extraction.
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?
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