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View Full Version : Attention 2.4Ghz Radio Users


Darin Jordan
09-07-2010, 04:25 PM
It was brought to my attention today that there are some servos from Hitec, and possibly others, that don't "play" well with the low voltage, 3.2V, output signal of the new 2.4Ghz systems.

Spektrum sells an inline comparator that boosts the signal voltage. Part number is SPMCP, and can be found on the Horizon Hobby site, here:

http://www.horizonhobby.com/Products/Default.aspx?ProdID=SPMCP

http://www.horizonhobby.com/ProdInfo/SPM/450/SPMCP-450.jpg


Thanks to Doug Smock for reporting the "issue" and bringing the solution to my attention. :thumbup1:
Jeff
09-07-2010, 06:20 PM
Looks like a "patch " cable to me.

Jeff
Flying Scotsman
09-07-2010, 06:33 PM
Am I missing something here, if you disable the bec circuitry and use a seperate power source, would this not solve the problem.

Douggie
egneg
09-07-2010, 07:00 PM
It looks to me like folks are being charged a fee to remedy an engineering screw up.
alvinsmith75
09-07-2010, 07:07 PM
I thought the esc's bec determined the voltage output?
Doug Smock
09-07-2010, 07:10 PM
Am I missing something here, if you disable the bec circuitry and use a seperate power source, would this not solve the problem.

Douggie

No sir.

Doug
AndyKunz
09-07-2010, 07:35 PM
The POWER comes from the BEC. This is typically about 5V. The SIGNAL comes from the receiver. On the Spektrum (and many other modern rx's) this is about 3.2V. Modern servos don't have a problem with this, but older ones will because they're expecting the SIGNAL to be pretty close (75% or higher) of the POWER voltage.

I take it that you got the e-mail from John, Doug? I asked him to send it direct but had a CDL physical this afternoon and haven't checked back.

Andy
sailr
09-07-2010, 07:52 PM
Is this just for Spektrum radios that have the problem or.....?
Doug Smock
09-07-2010, 08:36 PM
The POWER comes from the BEC. This is typically about 5V. The SIGNAL comes from the receiver. On the Spektrum (and many other modern rx's) this is about 3.2V. Modern servos don't have a problem with this, but older ones will because they're expecting the SIGNAL to be pretty close (75% or higher) of the POWER voltage.

I take it that you got the e-mail from John, Doug? I asked him to send it direct but had a CDL physical this afternoon and haven't checked back.

Andy

Yes sir I did. Thanks again for taking the time to get me (us) an answer.

You da man!!!
Doug
BTW fellas, I was only having trouble with Hitec HS 645 and 985MGs. These MR200s have been flawless in my P- Limited setups with HS 225MGs.
Another note: My MR3000s don't have a issue with either of the above servos.