Silly question 2

[Rich Griff]

My Ian Silcocks SHADOW ( wot4 like ) 4 channel with Futaba challenger radio gear and Magnum gp40 engine is probably over 30 by now and has been in the loft for the past 20 years, apart from an occasional day out to run the engine and check over.

It was in autumn 2019 that it was checked over last as I wanted to go model flying again, then covid kicked off.

Anyways black wire corrosion was found in the tx battery to switch wire. This is odd because the stuff was stored with all batteries disconnected ?

One wire corroded, then all wires suspect, so new radio gear needed.

I have read somewhere that spectrum Rx can brown out with lots of servos and 4.8v battery.

So, using a spectrum ar410rx at 6v, connected to Futaba fps148 servo, 4 servos, will the servos work and not be overpowered, over volted, at 6v ?

[Matt Carlton]

148 servos are fine on 6v 👍

[Frank Skilbeck]

I have run 148s and 3003s on a 5 cell Nimh battery with no problems.

Good decision to bin the switch, even if the wires looked OK, if the contacts had got any corrosion then it could have a high resistance which would could cause a large voltage drop under load.

[Nigel R]

"I have read somewhere that spectrum Rx can brown out with lots of servos and 4.8v battery."

an old myth

long since made irrelevant by (a) looking after your kit and (b) tech improvements

on the very early RX the brown out voltage was closer to 4V than 3V (now very much the other way around), and the signal reacquisition time (after brown out was over) was quite long (now made very much quicker)

ar410x is very much current gen, you will have no problem with a 4.8V AA nimh pack and four servos.

[Rich Griff]

Thanks again for the replies. The shadow servos will be checked visually, and with a servo checker I made, may have been an rcme article.

I will try and post some pictures of the servo checker, an easy home made bit of kit.

[robert chamberlain]

The term "brown" out is interesting as it applies to high servo loads. BUT,-just what it the time line ? Is it one second, or is it five seconds? Of course any interruption is not good, and it depends how high you are, but what are the numbers?? As usual ,thanks. Bob C

[Denis Watkins]

Posted by robert chamberlain on 22/01/2021 03:59:24:

The term "brown" out is interesting as it applies to high servo loads. BUT,-just what it the time line ? Is it one second, or is it five seconds? Of course any interruption is not good, and it depends how high you are, but what are the numbers?? As usual ,thanks. Bob C

Initially, 2.4gig was used by the Military, to operate in " signal crowded environments " and among the developments was the ability to find "another clear channel " and a spin off of this was a receiver that could lose its signal contact but importantly for us, the receiver could re-aquire the signal.

With Telemetry, lads have recorded these " fades " and " loses " and their time line varies due to circumstances but can be milliseconds or more usually half to one second.

2.4ghz gear is designed to cope with this.

Our Brownout, we speak of here, is more usually a voltage drop below the receivers operating voltage,, but as we leave the sticks alone, the flight pack often recovers enough to give some control

So, to get back home, consciously use one stick at a time ! ! !

We can, and do reduce problem by having a clear airborne pack charge and check regime, before take off.

Edited By Denis Watkins on 22/01/2021 07:17:55

[MattyB]

Whilst the need for well thought out and operated power supply remains, true brown outs (where the receiver sees low voltage, turns off, the load comes off and the voltage temprarily recovers to allow a reboot) are almost a completely historical issue. In the early days of 2.4Ghz systems some receivers would reboot at voltages where the servos were still operating, but nowadays they will generally operate down to ~3.1V which is lower than most servos will function at. Slow reboots (which Spektrum definitely suffered from in the early days) are also a thing of the past with all modern receivers.

The result is that brownouts are now extremely rare; if you have a dodgy power supply it will operate a modern RX and servos for slightly longer, but being able to drive the servos will be the limiting factor rather than the Rx. As a result if you do lose control due to a power supply issue it is now less likely to come back when you unload the sticks. In short always make sure your power supply is appropriate and you will be fine irrelevant of the system chosen.

Edited By MattyB on 22/01/2021 09:30:40

[Nigel R]

"The term "brown" out is interesting as it applies to high servo loads. "

Whilst I cannot add anything useful to MattyB's post, I would reiterate that it only ever applied to a poorly chosen or malfunctioning power supply (battery, bec, switch, wiring, etc).