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Radio brownout - Lost another pair of underwear (and confidence in the plane)

Bartman

Bartman

Defender of the Noob!
Judge said:
Couple of comments.

I have never seen a "power rating" for a receiver, or a "limit" published , for any brand.

I have asked people who would know if either one of the 2 major brands have ever seen a receiver in their service center that was cooked due to being "over amped". Neither one has.

I witnessed a beer driven experiment with a brand new RX several years ago where a steady 6-volt load was applied to it and the load increased slowly in 5 amp steps to see if it would fail. It did, at around 80 amps. And that was after several seconds at that load.

Conclusion? Worrying about cooking a RX due to much load is really not something that is possible under even the most extraordinary situations for us.
Click to expand...

that makes a lot of sense Judge. the servos are getting power directly from the bus bars where the servos and batteries are connected. it's the other components in the receiver that have might have limitations. the cross section of those bus bars will determine the current carrying capacity but most of the draw is going in the battery connection and right back out through the servo connections with the signal (white or light yellow wire) coming from the innards of the receiver.

not trying to educate you Judge, just fillingin the gaps in case anyone reading this isn't up on this stuff.
 
Judge

Judge

70cc twin V2
Bartman said:
that makes a lot of sense Judge. the servos are getting power directly from the bus bars where the servos and batteries are connected. it's the other components in the receiver that have might have limitations.
Click to expand...

The other parts of the RX never see either the voltage or load applied by the servos. Most RXs have a voltage regulator that sets the voltage the internal circuits see so what the servos are seeing/doing will have little effect on the rest of the RX.

the cross section of those bus bars will determine the current carrying capacity but most of the draw is going in the battery connection and right back out through the servo connections with the signal (white or light yellow wire) coming from the innards of the receiver.

not trying to educate you Judge, just filling in the gaps in case anyone reading this isn't up on this stuff.
Click to expand...

Yep, that is how they most all work. The signal voltage is generally around 3 volts and does not vary, it is the internal RX voltage that the RX sees after it is regulated down. Higher servo loads will have no effect on that voltage. It remains constant.
 
Bartman

Bartman

Defender of the Noob!
Judge said:
Most RXs have a voltage regulator that sets the voltage the internal circuits see so what the servos are seeing/doing will have little effect on the rest of the RX.
Click to expand...

i was going to mention that also, that the voltage regulator in there is also a limiting factor on what can be applied by the battery as too much voltage will cook the regulator. we see this with flight control systems for multi-rotor helicopters, voltage limits based on componentry and regulators.
 
Judge

Judge

70cc twin V2
Bartman said:
i was going to mention that also, that the voltage regulator in there is also a limiting factor on what can be applied by the battery as too much voltage will cook the regulator. .
Click to expand...

I have never seen that on any airplane. I have tested a number of Futaba receivers with 3S lipo unregulated pulling 10 amp loads through the RX, never failed to work. This was bench testing only.
 
djmoose

djmoose

70cc twin V2
njswede said:
The PowerExpander Pro. Probably about 2 years old. Came with the plane...
Click to expand...
Just a thought...maybe try to power the rx by itself without the smart-fly....you can keep it in there...just run power to it.
From what you describe...it was a brown out so eliminate the regulator all together.

Also. Here is something I never fully understood. A few years ago the smart-flys's did not support high voltage. I remember talking to the smart-fly guy asking if he would ever add that...and he said there was no need. Maybe he misunderstood what I was asking...but all of a sudden, they support over 8 volts now.

Did something change? Did they update the rx regulator? Is this an 'unupdated' non-HV version that is causing problems with the regulator? (Maybe I'm totally off base...but it might be worth a call to smart-fly to ask these question and have them sign-off on your setup.)

Just my two cents...hope it helps!
 
njswede

njswede

150cc
Yeah, I think I'll try that. On a completely different note: Are you making it to VMworld this year? If you are and have time, drinks are on me!
 
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