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Old May 17, 2009, 06:12 PM
Up in smoke!
BlueFFF's Avatar
Greenville, TX
Joined Jun 2007
627 Posts
MoFl,

I did some more testing. I put the old batteries back in and things seem fine for a few minutes then once the power light on the TX goes from solid green to a sort of blinking yellowish orange color the TX looses contact with the receiver. I placed my voltage tester on it and with the TX off there is about 10.9V at the battery. Turn the TX on and it begins dropping. The power light begins to blink yellow at 10.7V and then the receiver looses signal.

I know your saying 7V should be enough to keep the TX working, but my testing shows a lack of signal strength at less then 10.7V. This is a bit disappointing. I remember someone saying when they tried to power there TX on 2 cell lipo they had trouble with the TX not functioning properly (they lost there mixes or something like that). I'm sure it's in this thread someplace.

That's what I'm seeing here with this TX anyway.

BlueFFF
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Old May 17, 2009, 06:34 PM
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earlwb's Avatar
USA, TX, Grapevine
Joined Dec 2008
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They are using simple inexpensive LM7805 voltage regulators (one large and one small) inside on the encoder board. The 7805 tends to drop out at around 10v, some chips work better than others. In this case they are using clones or copies of the voltage regulators, which are not likely to be as good as the brand name ones. So I suspect the voltage regulators on the encoder board are likely dropping out at a higher voltage.
I think if one replaced the regulators with brand name good ones, they would be less likely to have the problem.

Another thought is although you are measuring 10.7 volts when the transmitter starts to lose power, the batteries may have been depleted and can't provide enough current to keep the transmitter going properly. Especially the AA dry cells.
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Old May 17, 2009, 07:00 PM
Up in smoke!
BlueFFF's Avatar
Greenville, TX
Joined Jun 2007
627 Posts
Thanks earlwb,
That makes sence. The batteries have been around awhile and are probably drained. It's good to know that the voltage regulators might also cause this effect. I think I will try to find a slim 3 cell lipo for it.
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Old May 17, 2009, 11:22 PM
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United States, OH, Galena
Joined Jul 2003
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Quote:
Originally Posted by MoFl
Some posts back (726) JMPblackfoot suggested to bypass the regulators and use just 4 NiMH cells. .
More on the 4-cell exercise in my Hobby City 2.4 GHz 4-channel transmitter:
I wanted to check operation with a low battery. To this effect, I discharged the 4-cell 2100 mAh Eneloop battery completely, then pumped just 100 mAh into it.
I then left the transmitter "on" until discharged, while watching a servo connected to channel 1 of the receiver. The servo did not budge until the transmitter voltage dropped to 3.7V. Then it went "crazy" for a few moments and finally "died".
Regarding the voltage monitor LED, I soldered a red LED (Kingbright L-53ID-5V is what I had at hand) across R21 (in lower left corner of the schematic diagram).
The transmitter LED is green when fresh off charge. It becomes orange when the voltage drops to around 5.0V. However it goes blinking red only when the voltage is down to 3.8V and very little operating time remains.
That is the best solution I have found so far. I can live with it since it does confirm that the battery has been charged, and a charge is good for at least 10 hours...
Finally, for the curious amongst us, I have checked with an oscilloscope that there is indeed is a 50 mV p-p noise on the 4.8V supply, which does not appear to have any detrimental effect whatsoever on the operation of the system. I guess that the voltage conversions are done during the "rest" periods of the RF transmission
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Old May 18, 2009, 12:54 AM
I enjoy the voices
Lead Wings's Avatar
Perth, Australia
Joined Apr 2007
484 Posts
Quote:
Originally Posted by abbydawn
I've been watching for a hack on a Hitec Optic 6 as I want to do similar using my Turborix RF board. If you can I would appreciate the wiring connections/mods needed. PM if desired? I would be removing the 72Mhz capability. Mine is the Hitec Sport version TX and appears to have a seperate RF board so removing it entirely seems feasible. It doesn't appear HK will offer a plugin or a self contained 9X specifically for their HK receivers so hack is on.
Thx in advance.
Hi, of it's any help have a look at the Assan hack threads - I know someone there has posted doing there Laser 6 there - may be similar and help you find the connections etc requried. Do a search on Hitec or start around post 89.

Basically he cut into the trainer port wires to get +, PPM etc, and putting a switch on there disabled the FM when requried (ie could switch between FM and 2.4 GHz). You could set yours up the same way but with the FlySky unit.

http://www.rcgroups.com/forums/showt...=994433&page=6
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Old May 18, 2009, 06:06 AM
SansHeli
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Brisbane, Australia
Joined Nov 2006
13 Posts
Trainer Socket / FMS Simulator Software

Has anyone been able to (if at all possible) use the likes of FMS simulator software with the Turborix TX through the Trainer socket? I have a Hi-Tech USB adaptor that I use with my JR Sport 400 radio and FMS - would that work with the Turborix if I made a suitable adaptor (from JR trainer socket to Turborix Trainer socket)?

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Old May 18, 2009, 01:44 PM
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United States, OH, Galena
Joined Jul 2003
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Quote:
Originally Posted by JMP_blackfoot
Update on the 4-cell exercise in my Hobby City 2.4 GHz 4-channel transmitter:
I removed R21 and now the low-voltage alarm (blinking red LED) comes when the voltage is down to 4.17V. After that, the transmitter works for another 10~11 minutes.
The arrangement for voltage battery monitoring is now as shown.
The weather is beautiful, I'm going out to fly.
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Old May 18, 2009, 04:42 PM
Time for another motto!
Utrecht, The Netherlands
Joined Jul 2006
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I have had my turborix radio modified by adding a resistor parallel to r31 (IIRC). now it goes to full red at ~7 volt. It works ok with 2s. The switch from green to amber (~8 volt) happens after 30 mins on a full charge. The other phase (amebr to red) is much harder to see, but that is true for the old values too.
Sorry, I don't know the resistor values and I'm too lazy to open the transmitter up and measure them..
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Old May 19, 2009, 11:50 AM
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Joined Oct 2008
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The manual for FLYSKY is at:
www.helipro-rc.com/download/RADIO%20MANUAL.pdf
From the photos, it looks to be identical to the Hobby King 6 channel. Which has a not too bad price of $33 plus $21 shipping.
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Old May 19, 2009, 01:09 PM
R.I.P, Aardvark.
F-111 John's Avatar
Holt, MI
Joined Jan 2009
1,554 Posts
Quote:
Originally Posted by wlfaries
The manual for FLYSKY is at:
www.helipro-rc.com/download/RADIO%20MANUAL.pdf
From the photos, it looks to be identical to the Hobby King 6 channel. Which has a not too bad price of $33 plus $21 shipping.
Plus either $2.99 or $4.29 for the USB cable to program it.

Very competitive with the same radio from R2 Hobbies or SN Hobbies, at least when you take into account shipping to the United States. The radios from R2 and SN also include a USB cable, although it is only for Windows XP. Drivers are available for Vista, but since I haven't tried it personally I can't say for certain if it does work with those radios. I might buy one and find out, however.

I did post a link to the Vista drivers earlier in this thread, however.
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Old May 19, 2009, 01:19 PM
Curiouser and curiouser
Kokopeli's Avatar
Rochester, NY, USA
Joined Oct 2005
2,061 Posts
battery status lights

Quote:
Originally Posted by JelleB
I have had my turborix radio modified by adding a resistor parallel to r31 (IIRC). now it goes to full red at ~7 volt. It works ok with 2s. The switch from green to amber (~8 volt) happens after 30 mins on a full charge. The other phase (amebr to red) is much harder to see, but that is true for the old values too.
Sorry, I don't know the resistor values and I'm too lazy to open the transmitter up and measure them..
These are measurements I made on my HK-T4A transmitter - so they may or may not be the same as yours before modification - I suspect the circuits were the same - so maybe these measurement will be of some use to you.
Transition from green to amber occurs at 9.3 volts
Transition from amber to flashing red occurs at 8.3 volts.
Since NiMH full charge voltage is about 9.6 volts, indeed there will be very little transmitting time before the voltage falls to the amber range.
It would be nice to know at what voltage the transmitter stops transmitting, eh?

Walt
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Last edited by Kokopeli; May 19, 2009 at 01:25 PM.
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Old May 19, 2009, 01:45 PM
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MoFl's Avatar
Espaņa, AL, Sevilla
Joined Apr 2007
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Quote:
Originally Posted by wjbite
...
It would be nice to know at what voltage the transmitter stops transmitting, eh?

Walt
This subject has been discussed previously in the thread.

In theory, without mods, it shouldn't give problems down to 7 V or maybe 6.5V, because battery voltage is converted to +5V by two linear regulators, one for MCU-encoder circuit, and another one for the RF-transmitter module. Furthermore, the RF module regulates again this +5V to 3.3V (not a good example of efficient design)

So, as 2 V (or even 1.5V) is enough overhead for most regulators to do their work, the electronics should behave well above 7V.

BUT Bluefff has reported having less range below 10 V. This could be caused by an out of specs regulator.

On the other hand, JMP_blackfoot has got it working even with 3 NiMH cells, after bridging the regulators.
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Old May 19, 2009, 02:29 PM
The reviewer
XJet's Avatar
Tokoroa
Joined Mar 2004
3,827 Posts
Quote:
Originally Posted by wjbite
Since NiMH full charge voltage is about 9.6 volts, indeed there will be very little transmitting time before the voltage falls to the amber range.
Actually, NiMH cells have a *nominal* voltage of 1.25V per cell -- which equates to 10V for a charged pack.

Most 8-cell NiMH packs actually come off the charger at about 11V but quickly settle to around 10.4-10.6V

A good pack subjected to a light (0.5C or less) will generally deliver most of its energy while >9.6V so the voltage warning settings are pretty good.

However, I'd land once things turn amber because once a pack gets down to 9.4V it's the voltage will then fall *very* fast -- leaving you probably no more than three or four minutes of flight time.
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Old May 19, 2009, 03:11 PM
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Joined Nov 2004
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Quote:
Originally Posted by MoFl
So, as 2 V (or even 1.5V) is enough overhead for most regulators to do their work, the electronics should behave well above 7V.
That sounds great for those like me that would like to use 2s lipo. I added a JST connector to the battery terminals, and tested with my 2s battery. The battery indicator was bright red, but the tx/rx binding process worked fine, and the servos seemed to respond as expected. This was using a 2s lipo at about 7.8V. I wonder about BlueFFF's poor results at below 10v. Perhaps there was some other issue at play? It sounds like we need some testing done with variable voltage power supply to determine actual low voltage limits.

Quote:
I think the best hack for this TX's powering is to use a 2s or 3s LiPo (or any kind of battery above 7 Volts), keep the existing linear regulator for the encoder part (which has a low consumption), and replace the bigger 5 volt regulator (which feeds the more power hungry RF module) with a 3.3 switching regulator, connecting it's output directly to the 3.3 volt rail at the RF module (this module is feeded with +5v, but they are directly converted to 3.3 V at the input).
I understand the desire to improve efficiency by using the 3.3v switching regulator to power the hungry RF module. However, are we still not then limited to the 7V due to the existing linear regulator in the encoder board? Any thoughts on using a single switching regulator to power both boards?
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Old May 19, 2009, 03:39 PM
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MoFl's Avatar
Espaņa, AL, Sevilla
Joined Apr 2007
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Quote:
Originally Posted by renns
...
I understand the desire to improve efficiency by using the 3.3v switching regulator to power the hungry RF module. However, are we still not then limited to the 7V due to the existing linear regulator in the encoder board?
Yes, but as the 7 V get efficiently converted to +3.3 V, you might have more cells but of less mAh, for a given time of use.

With linear regulators, mA at the input = mA at the output (lets say at the RF module). So, if the RF module drains 150 mA, battery life (h) = battery mAH/150mA, regardless the battery volts. Power wasted in heat at the reg (mW) = (Vbat-Vmodule)*150

With a 100% efficient regulator, mW at the input = mW at the output; as mW=mA*V, if the RF module drains 150 mA @ 3.3 V then battery life (h) = battery mAH*Vbat/(3.3*150), thus increasing battery life in the ratio vBat/3.3V This is why is better to convert efficiently to 3.3 instead of 5.0

Of course, in the real world, thins are a bit worse. Efficiency could be arround 85% (though there are better regulators), and if you keep the linear regulator at the encoder (for simplicity), there's an aditional load (encoder may drain about 25 mA)

Quote:
Originally Posted by renns
...
Any thoughts on using a single switching regulator to power both boards?
It's possible, but you loose the isolation between encoder and RF power rails provided by the use of independant regulatos. Also, you'd have to choose if the single regulator is 5V (loosing the advantage of going down to 3.3 in the power hungry part) or 3.3 V (I'm not sure if the MCU would go OK at this voltage level).
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Last edited by MoFl; May 20, 2009 at 02:31 AM.
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