T-Rex 500 Info

[TrexMADuk]

Me too - I would only fly an electric heli on 2.4ghz - to many glitch problems with 35mhz, but would prob run a sep bec and lipo on the 500 for the moment...its a BEC problem not the radios.... in fact I only fly 2.4ghz on any model I value...

[Ashley Davis]

I'm going to run the Western Digital Hercules BEC, it runs straight of 6S and can deliver 5A.....so no need for a separate lipo. It's switchable between 5V and 6V as well.

[Tim Procter]

Me too - I would only fly an electric heli on 2.4ghz - to many glitch problems with 35mhz, but would prob run a sep bec and lipo on the 500 for the moment...its a BEC problem not the radios....

Think you are on the right lines..

Just to add this thread has been very helpful to everyone and deserves a thanks to all who are testing here..

[TrexMADuk]

Western Digital Hercules BEC - wht did'nt I think of that - good idea

[Ashley Davis]

The DCUP has a button on it, hold it in for a few seconds after connection and it resets the lowest voltage read figure. No need to go plugging / unplugging stuff.

[ktargett]

I am more interested how susceptable to interference the 500 heli is.

For example:
TREX 450 SE - fairly bad, but with a bit of work can be flown fine.
Dragonus pro - very bad, with a lot of work could be fine
Mini-titan - no problems (mostly due to it being mainly plastic I guess)

Cheers

Kevin

[ktargett]

The main problem with switching regs for the BEC is their ability to maintain a consistent output with large fast changes in either input voltage or output current load.

To filter out noise and spikes you need to use different sizes of cap to filter out different frequencies of noise - 1 very large cap is slow to react to high frequencies. They may also upset the switching regulators if placed directly on their output, upsetting the feedback loop - and potentially make things worse!

Kevin

[Edders]

The DCUP has a button on it, hold it in for a few seconds after connection and it resets the lowest voltage read figure. No need to go plugging / unplugging stuff.

knew I should have read the manual properly

As said all those blaming 2.4 should have a re-read though the posts.
the spectrum gear only switches off at 3.3/3.4v other than the issue here if your receivers only receiving a voltage that low you've got other problems to worry about like forgetting to charge batteries ect. all electronics will cut out at some point 3.3/3.4v is pretty low and yes due to the way 2.4 works it takes a 1-2second reset but it shouldn't have got that low in the first place.So look elsewhere.

I cant find the real voltage that a "normal 35mhz" receiver shutdown? (may try to do a test later)

the other issue at the moment that I have is I cant find a way of measuring the "real" low voltage as the data loggers don't have high enough sampling rates to detect those millisecond blips. I am working on this though...

Edders

[Edders]

The main problem with switching regs for the BEC is their ability to maintain a consistent output with large fast changes in either input voltage or output current load.

To filter out noise and spikes you need to use different sizes of cap to filter out different frequencies of noise - 1 very large cap is slow to react to high frequencies. They may also upset the switching regulators if placed directly on their output, upsetting the feedback loop - and potentially make things worse!

Kevin

See specs here I think this one has a capacitors to prevent / help this
http://www.realraptors.co.uk/zen-car...oducts_id=2877


Edders

[Ashley Davis]

PPM/PCM start to get dodgy around 3V depending on make. I've seen them work as low as 2V but I'd be suprised if they could still modulate a signal at this low voltage. PCM/DSP is likely to be closer to 3V as there is a processor involved.

[Ashley Davis]

correct Edders, the Hercules has two bloody huge caps on it to smooth the output. One of the reasons I'm using it.

[Ashley Davis]

For those interested, I have tested that BEC and done a small write up on the blog:

http://www.trextuning.com/blog/?p=201

[ChrisB]

Going out on a limb here but reading all this brownout stuff and how the BEC works,has anybody heard of a shutdown on anything other than a 6s pack..

What if say a 4s or 5s pack cures the problem?


Has this been tested to see how the ESC and BEC perform?


Scenario..

You are wazzing around with your high capacity heavy 6s pack,you offload the head and the voltage spikes up and 25.2 V is its maximum input level,BEC says stuff you my old son and does a hissy fit.......

Align only state 2500mah 6s,what if the higher capacity packs are too heavy and too powerful?

sorta along the lines of what Barney said

[Ashley Davis]

If you want to try running yours off the ESC BEC your're welcome

But theoretically the BEC is less stressed at lower voltages.

[ChrisB]

If you want to try running yours off the ESC BEC your're welcome

But theoretically the BEC is less stressed at lower voltages.

This is my point Ash,has it been tested ?,a lower stressed BEC may be the cure,what if its over voltage shutting the power to the Rx down for a split second?