Feb 19, 2009, 05:05 PM
Registered User
España, AL, Sevilla
Joined Apr 2007
519 Posts
Hello, Hans.

I agree with you. No problem to run with 8xNiMh. The regulators would work OK down to 7 V (input).

With original values for R30 and R31 (as shown at post#227 schematics), voltage at pin 25 is 4,7/(4,7+10)=0,32 times Vbat, so, considering your measurements, lower threshold for steady orange is 3V at pin 25 (0,32*9,4), and upper threshold for steady red is 2.9V (0,32*9,1).

With R30=7K5, pin25=Vbat*0.385, so steady orange for Vbat>7.8 (3/0.385) and steady red for Vbat<7.5V (still good for the regulators). Instead of removing R30 and replacing it with another, it would be equivalent to solder a 30K resistor in parallel with existing R30.

If you want to be more conservative, you could fix upper limit for red at 8.0 V. To achieve this, R30 could be arround 8K3. It would be equivalent to solder a 50K resistor in parallel with existing R30 (see photo).

Another question: If power consumption is about 175 mA, lets say 25 mA for the MCU (small regulator U2) and 150mA for the RF module, then power dissipated at U3 (big regulator) with a fully charged 3S LiPo (12.6V) would be under 1,2 W (.15*(12.6-5)). From the datasheet, thermal resistance for a TO220 L7805C (junction to ambient, without heatsink) is 60ºC/W, so temp increase is 60*1,2=72ºC. As maximum junction temp is 150ºC, this means maximum ambient temperature (inside the case) is about 78ºC. So, I think no heatsink should be needed, although in extreme cases (45ºC air temperature, radio under direct sunlight) could be possible to reach 78ºC inside the case. This could be the case described at http://www.rcuniverse.com/forum/m_81...10/key_/tm.htm

Images

Last edited by MoFl; Jun 24, 2009 at 08:30 AM. Reason: Adding link to schematic, values for resistor in parallel with R30 and photo.
Feb 20, 2009, 03:11 AM
Registered User
The Netherlands, OV, Almelo
Joined Sep 2008
81 Posts
Thank you MoFi for the detailed description.

Quote:
 As maximum junction temp is 150W, this means maximum ambient temperature (inside the case) is about 78ºC.

I believe these 78XX regulators shut down at a specific temperature.
Of that happens it would be a disaster.
I think I'll stay at the save side, No Lipo (12 +) but NiMh (10+)

regards from hans
 Feb 20, 2009, 09:25 AM Registered User Joined Dec 2008 23 Posts Well I tried putting good dry (energizer) cells in the tx and tried both 4 dry cells for the rx, and powering it through a esc with a 7.2 batt and it still won't bind with either rx. I have the thing apart, I guess over the weekend I will try to power the tx with a 10 cell nimh subc stick pack and see if that helps but I'm doubting it since I'm getting a solid green light on the tx already. Is there any way to tell if the binding button is bad or anything else to try?
 Feb 20, 2009, 09:50 AM Registered User Rouen (FRANCE) Joined Nov 2003 69 Posts Hi 86waterpumper, can you tell us how you proceed to bind the RX, can you describe step by step what you are doing and how are the LEDs, i bind my RX with 8 Nimh not completly charged into the TX (i'm in orange) and 4 Nimh in RX side (not completly charge too) and have no problem. May be can see what to do if it still not working for you. Géo .
 Feb 20, 2009, 10:13 AM Registered User Joined Dec 2008 23 Posts Sure I can describe how I try to proceed. Maybe I am doing something wrong I hope so as I'd love to use this thing haha! I find hobby city gives no tech support at all...they told me "we know nothing about this product" hah Anyway first of all I stick the binding plug onto the prongs that say BATT on them. I have tried the plugs turned both directions it doesn't seem to matter either way, I'm not sure what the other end of the binding plug is for it doesn't seem to fit anything just to pull it off the pins with I guess. Anyway then I stick either a futaba 4 cell double a battery holder which came with a tx/rx combo it has a bec connector and a switch with on and off, and I have a regular car esc also I have used which should be giving the rx plenty of juice using that method too. I plug the connector with the black wire towards the short side of the rx and have tried to power through various channels 1 thorugh 4 etc. Upon doing this, the small led inside both the rx and the external antenna both begin to blink red. For some reason at least on one rx they do not blink exactly in unison. At this point, I push in the bind/range button on the tx and I switch the power to on, receiving a green light. No matter how long I hold in the button I never get anything but the steady red blinking on either rx. Like I say, the tx does work through the trainer port with fms (using audio microphone jack) and shows every channel operational on a analog device configuration and I can fly the planes on the sim with it even with the nimh batteries etc. Last edited by 86waterpumper; Feb 20, 2009 at 10:30 AM.
 Feb 20, 2009, 11:13 AM Registered User Rouen (FRANCE) Joined Nov 2003 69 Posts ok 86waterpumper, let see after binding when you release the bind button and wait for a while what happend ??? if LED still blinking, wait about 15 to 30 s and remove the match line (the binding plug) and watch the LED, if they stop blinking shut off the receiver, plug one servo and the battery to the BATT and test it. Let me know if it does not work, i'll assemble my radio back (all has been disassemble) to see what can be wrong for you. Géo .
 Feb 20, 2009, 11:30 AM Registered User Joined Dec 2008 23 Posts Ok I can throw the cover back on and try that tonight and see what it does. Thanks for trying to help me out! ...Ok I got home and tested it again. I put the cover back on the tx and get a solid green light on power on. I assume if it's green then it's getting enough juice to bind? For whatever reason it just doesn't. The lights just blink no matter how long you hold the bind button, and after being released they continue to blink, even after the bind cord is pulled off. I guess it is possible that I could have gotten two bad bind plugs? At any rate, I tried hooking a servo to one of the channels and it didn't move either direction the tx and rxs simply aren't communicating. What was weird is that for the heck of it I reversed the power plug and the led quit blinking and held solid so I got excited for a minute, but it still wouldn't work the servo and resumed it's blinking when I put the black wire back the other direction. It's a bummer becuase I can't send the thing back it's probably not worth the shipping to china lol. Does anybody need some extra rx? Last edited by 86waterpumper; Feb 20, 2009 at 06:04 PM.
 Feb 20, 2009, 06:49 PM Registered User Rouen (FRANCE) Joined Nov 2003 69 Posts Hi 86waterpumper, what we don't know is which one of the transmitter or the receiver fail, did you try without the satellite receiver (the smaller one). Do you have some measure instrument like ohmmeter or voltmeter with continuity tester, may be there is a bad contact between the bind button and the RF module, i could show you where testing from a photo of the main board and the RF module, may be you did it and all is ok, if not, it's like the button does nothing if push or not. Géo . you did the test with the antenna screw up and not to close the receiver ??? Last edited by geotrouvetout; Feb 20, 2009 at 06:55 PM.
 Feb 20, 2009, 07:45 PM Registered User Joined Dec 2008 23 Posts I agree, don't know what part is to blame, but I had guessed the tx. It would be odd to get two bad rx at once but I guess it's possible. Yes I have tried doing it without the small satellite hooked up and with it also. I have tried doing it with the tx close by and across the room etc. I do have a elec. tester it's crappy but I'm sure it will measure continuity as I have used it to test fuses etc...if you have a pic of what contacts to touch I can try that out.
Feb 20, 2009, 09:05 PM
Registered User
Rouen (FRANCE)
Joined Nov 2003
69 Posts
Ok here is the right of the main board and the RF module under the programming connector.
The black circle and arrow are the Gnd, the blue circle and arrow are the +5V, the red circle and arrow are the bind.
After having unscrewed the back from the radio, unplug the little connector on the left that connect the battery to the main board, and pull up the programming connector to have access to the RF module connecting wire.
Put you multimeter in the continuity position.
First test the continuity between the 2 black circles, and one black circle to black arrow.
Do the same with the blue.
Then between red circle and red arrow.
Test between red circle and black circle, at this time there is no continuity until you push the bind button.
After that, connect the battery connector back power on the radio and measure with your voltmeter (volt CC position) between one black circle (-) and one blue circle (+), avoid short circuit, and you should read 5 Volts.
first is to see if there is bad contacts and the bind button is right.
second is to see the RF module is powered with the good voltage.

Géo .

Ok here it's 4 AM , i go to bed and talk to you tomorrow (or today )

Images

Last edited by geotrouvetout; Feb 20, 2009 at 09:10 PM.
Feb 20, 2009, 11:25 PM
Lincoln, CA
Joined Oct 2006
8,435 Posts
Another Thought

Quote:
 Originally Posted by 86waterpumper I agree, don't know what part is to blame, but I had guessed the tx. It would be odd to get two bad rx at once but I guess it's possible. Yes I have tried doing it without the small satellite hooked up and with it also. I have tried doing it with the tx close by and across the room etc. I do have a elec. tester it's crappy but I'm sure it will measure continuity as I have used it to test fuses etc...if you have a pic of what contacts to touch I can try that out.
I read and reread your binding procedure and it looks perfect. This is my suggestion. Order another transmitter (&rcvr) from HK and then you will have enough pieces and parts to troubleshoot anything. Just a thought.
I have 2 HK systems and 1 Turborix and 10 HK rcvrs (any and all mixed and unmixed configurations work great). I have tell you how much easier it is to troubleshoot any situation. Oh, BTW, 2 of the 10 binding plug had their wires clamped on the insulation and did not work until I took them apart and soldered them back together. The binding plug is just a wire and it has no forward or backward to it (i.e. - it can be hooked up either way to the BAT port).
I checked something else too that might help (your peace of mind, at least). Since you mentioned that you had a blinking light on the rcvr and aux rcvr, I know that you had the battery hooked up right and the binding plug on the BAT port. Ergo, the rcvr is acting exactly as it should with the transmitter off. Any other configuration would not allow the blinking (I just tried the many other possibilities). So, I concur with you that it is probably a bad transmitter. Keep us posted, I am following this so I can learn something too. Good luck.
AJ
 Feb 21, 2009, 02:32 AM The reviewer Tokoroa Joined Mar 2004 3,827 Posts Try holding down the bind button while you turn the transmitter on.
 Feb 21, 2009, 06:10 AM Registered User Joined May 2004 605 Posts Seems to me there is a market for this TX module and recievers for the DIY crowd. I wonder how much LESS it would cost to purchase without the TX case, etc? A 6ch TX module (with ant) and RX for under \$25USD? Think about it..... Dave
 Feb 21, 2009, 06:53 AM Registered User Rouen (FRANCE) Joined Nov 2003 69 Posts Hi HobbyCNC, i agree with you, but much less than 25\$USD, for the module whatever 4ch or 6ch are the same, i have tried to found where getting the module only and get no answer. And that can saving a lot of shipping cost (few grams instead of few hundred). Géo .
Feb 21, 2009, 09:20 AM
Registered User
España, AL, Sevilla
Joined Apr 2007
519 Posts

Quote:
 Originally Posted by HobbyCNC Did I miss the post saying what the output power is? 100mw? 50mw? Thanks Dave
In the manual says 19 dB, about 80 mW.

In the web page, less than 20 dB (20dB=100mw). Quite a strange way of giving specs (maybe 20 dB a legal limit somewhere).

dBm-mW conversion: P(dBm)=10*log(P(mW)/1mW)

http://en.wikipedia.org/wiki/DBm
http://en.wikipedia.org/wiki/Decibel