Espritmodel.com Telemetry Radio
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Old May 01, 2010, 07:47 PM
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Success!

So... I have some good news to report. This project is a success! It works!

On the advice of a friend i ended up using an HEF4010 instead of the other two IC's mentioned earlier and this one worked a charm right from the start. This buffering issue was indeed my only problem. Very happy with the results.

Range is at least 1-2 meters (which is more than I need for this application) with an antenna of 23cm on the transmitter only. For some reason beyond my understanding, when i attach any sort of antenna to the receiver, it practically kills reception and range becomes very short and unreliable.

I've attached some pictures of the "Revision 1" modules. The wireless headtracker module will be built into a pair of Fatshark goggles and the trainer port "dongle" will eventually be refined to look nicer, be less in the way, and the entire system will be modified to still accept a PPM signal in for buddy boxing.

Pretty happy with the results and I appreciate the advise and comments the two of you (Rich and Ian) gave me. Helped alot!
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Old May 01, 2010, 08:03 PM
7000mw of raw power!
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Those 4000 series are great. Even though older than LS they are still popular. They work from 1.5-12v and it tales almost nothing to drive them.

I'm shocked that buffering was the problem. The OOK units I have including those from Sparkfun had plenty of drive from the LM358s. Good job.
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Old May 01, 2010, 08:38 PM
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In case anyone else would like to try this, Here is a list of the parts i ended up using:

Transmitter and Receiver modules:
http://www.sparkfun.com/commerce/pro...oducts_id=8945
http://www.sparkfun.com/commerce/pro...oducts_id=8947
(23cm antenna on the TX)

Hex Non Inverting buffer (HEF4010 / HCF4010):
http://pdf1.alldatasheet.com/datashe...S/HCF4010.html

5V regulator for receiver module:
Any will do. I actually used the BEC from an old tiny 10A brushed ESC. It was small and gave me the +5V i needed for the RX module from the 9C trainer port.

The 4010 IC needs voltage to pins 1 & 16. Signal goes in on pin 3 and comes out buffered on pin 2. Ground to pin 8.

PPM out from your headtracker goes on the data pin of the TX module and you should see the PPM train on the data pin of the RX module.

Earlier in this thread there is a picture of the Futaba 9C trainer port pinout. One of the voltage pins will give you voltage regardless of whether the Futaba radio is on or off and the other will only give voltage when the radio is on. I used this one. Data out pin from your RX module goes to PPM IN of the futaba radio and you will need to regulate the +/-12V from the Futaba radio to between 4.5 & 5.5v for the RX module.

That's all there was to it.

All in all, it was maybe 15 USD in parts to build this wireless conversion and for me its absolutely worth it to not have to worry about that stupid cable between my head and my radio anymore. i can set my radio down with out worrying about ripping my goggles off my head and its one less thing to have to carry around with me.
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Old May 02, 2010, 04:45 AM
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Quote:
Originally Posted by AnnihilaT View Post
So... I have some good news to report. This project is a success! It works!

On the advice of a friend i ended up using an HEF4010 instead of the other two IC's mentioned earlier and this one worked a charm right from the start.
Thats the FET inputs of the CMOS 4000 series working for you, i.e. next to no current.

Nice one!, glad to see another problem solved.

Ian.
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Old May 02, 2010, 05:04 AM
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Thanks Ian!

@Rich: Did the OOK units from spark fun that you used have a datasheet ? Im curious because the ones i used clearly stated that 10 uA was the max output current. In the beginning i just didnt know what that meant.

EDIT: The ones im using are ASK not OOK... if im correct thats something different so maybe even we are talking about different modules here?
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Old May 02, 2010, 05:43 PM
7000mw of raw power!
rich smith's Avatar
New Hampshire (not the old one)
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I picked them up from Sparkfun a cuople years back and they look very similar to your link. Not sure if I even downloaded or looked at specs from them. It's possible they have changed. Of the dozen or so different types none are as weak as 10us. That strikes me as almost useless. Your results are pretty clear though.
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Old May 02, 2010, 05:45 PM
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yeh i was just checking into it again and realized these ones i used are ASK and not OOK (I believe thats something fundamentally different?) so im thinking prolly I used something a bit different than you had.
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Old May 02, 2010, 05:48 PM
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One last vid showing a bit more of the system working:

Wireless Headtracking module (2 min 37 sec)
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Old May 02, 2010, 05:59 PM
7000mw of raw power!
rich smith's Avatar
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Originally Posted by AnnihilaT View Post
yeh i was just checking into it again and realized these ones i used are ASK and not OOK (I believe thats something fundamentally different?).
Nope, ASK (Amplitude Shift keying) = OOK (On-Off Keying)

Who knows, the important thing is you got it working. You've discovered as I did, PPM does work over short distance because it is a continuous signal unlike rs232.
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Old May 04, 2010, 04:12 PM
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Excellent work here. I'm thinking of giving this a shot. Is there a basic schematic here?? I believe I understand the components, just the actual wiring?? Thanks and great work.
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Old May 04, 2010, 05:50 PM
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Excellent work here. I'm thinking of giving this a shot. Is there a basic schematic here?? I believe I understand the components, just the actual wiring?? Thanks and great work.
It's such a simple circuit im not really sure a schematic is needed... have a look here:

http://www.rcgroups.com/forums/showp...8&postcount=33

if you still have any questions about the wiring just ask and let me know what you dont understand and ill help the best i can
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Old May 04, 2010, 07:08 PM
Don't leave it Stock
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http://www.rcgroups.com/forums/showp...0&postcount=25

Another diagram part of the equation?
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Old May 20, 2010, 01:11 AM
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Ordered the parts tonight. Looks to be exactly what I was lookin for!!
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Old May 20, 2010, 03:01 AM
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Originally Posted by mrfliboy View Post
http://www.rcgroups.com/forums/showp...0&postcount=25

Another diagram part of the equation?
This chip isnt actually used anymore... during planning i was going to use one of these but did not in the end.
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Old May 20, 2010, 03:02 AM
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Originally Posted by braindead4554 View Post
Ordered the parts tonight. Looks to be exactly what I was lookin for!!
Good luck! BTW, What frequency did you order and also which frequency are you using for your video link?
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