Frequency Hopping experiments on the NRF24 & full tx/rx

[Tobe]

Have to second Phil as I never had any issues of that character however all my board have the additional capacitors on the power input to the nRF, 100uF Tant and a 100nF on top of the regular decoupling on the 3.3V voltage regulator.

[John Ryan]

Problems now all sorted. Managed to have a look at the supply rails on a friends scope. With all servos going we found the voltage was dropping up to 1.5v so we tried a 6v battery and every thing ground to a halt. We then hooked up an adjustable power supply and put a volt meter on the 5v output pin and it tracked the input voltage right up to 8v. The regulator is fried. Just bread boarded up another rx with a new nano RF and it works like a charm. Even works without any caps over the input. Magic stuff!

[John Ryan]

You've not been running the servos via the Nano's 5v regulator have you John?
All my rxs use a single lipo cell into the 5v input and to servo positives,
ie the 5v regulator has nothing to do, it has no input from vraw
Cheers
Phil

Hi Phil
Have been running the servos direct from the battery. Also been back on the scope and discovered the park HPX mini servos in the model really pull the voltage down. We then tried another model with 4 x Futaba 3003 servos and found hardly a ripple on the scope when stiring the sticks. The controls in the HXP model are quite free so they are not overloaded. Not all servos are created equal!
John

[Phil_G]

Sounds like the servos were the culprits John but doesnt explain a blown regulator - maybe just an ELF.
I would be very doubtful of that particular battery. Even your greedy servos shouldnt pull a 4-cell pack down to that extent.
Its all down to equiv series resistance, that pack sounds like it has a high esr. My gliders (Shauns too) are all on a single lipo cell, very low esr
and no discernable drop whatsoever when waggling servos

[Mike_K]

I'm late to the nRF24 radio gear party, everybody else is flying with it, I had a dabble when Phil first posted his radio, but I'm only now starting to get to grips with it.

The first thing I decided to do was re-check which of the RF-Nano I had were nRF24L01+ versions and not the older non-plus ones, using Phil's sketch (he describes it as a script).

viewtopic.php?p=8882#p8882

Everything reported a “plus” version, but I realise there's a minor flaw in the sketch as it reported that a standard Nano with no nRF24 was a plus as well…

The problem is that the “plus” version is reported by default, so if the SPI pins are incorrectly configured, there is a faulty nRF24 or if there is no nRF24 at all, it reports a “plus” version. It only reports a “non-plus” if the SPI is configured correctly and it finds a non-plus chip.

After reading through the nRF24 library documentation I found there's a function that checks if the nRF24 is connected (and the SPI is working correctly). Therefore I decided to modify Phil's sketch so that it first checks that the nRF24 is connected properly and only then it checks for the plus/non-plus version. The sketch now correctly reports that the SPI is not working correctly for a standard Nano and a faulty Tstar Techrf-Nano and a “non-plus” for one of the Keywish RF-Nano.

So it’s now a useful check that the nRF24L01+ SPI pins are correctly configured as well as reporting plus/non-plus.

[_AL_]

Could someone confirm if these are what I need for the TX & RX?

https://www.ebay.com.au/itm/18619116555 ... d_source=4


https://www.ebay.com.au/itm/26479044599 ... R5LDzPbhYw

Thanks.

[Phil_G]

Hi Al, no and yes
We found that the 'open' module can be troublesome, we use the screened version like this;
https://www.ebay.com.au/itm/196118482200

For the receiver, an easier option is the Keywish RF-Nano which is an NRF and a Nano on one PCB.
Cheers
Phil

[_AL_]

Thanks Phil.

[John Ryan]

I have a problem with my Arduino / NRF transmitter. It all works as it should and is in regular use. Every now and then when it's switched on the aileron resets its neutral position about 15deg off centre. I've tried another naro and also tried another NRF24. A recalibration fixes the problem. No other channel is affected. It will happen on a fully charged battery or one getting near stop flying voltage.
Im using a 6v NiMh battery with a 470mfd and 0.1mfd across the the supply rails into the V input of the Naro. Im reading 4.98v on the 5v pin. The NRF24 3.3v adaptor board is fed from the same supply.
Unfortunately, I can't with any common cause other than the naros coming from Bangood
I've also built and regularly fly Phils S/C FHSS system and never had a problem with it. Also tried the same battery.
Anyone got any suggestions?
PS its not resetting itself to the failsafe sitting this all works and never requires resetting

[Phil_G]

Hi John, from your description the electronics are working fine, those are the symptoms of a dicky or loose stick pot.
After reading the sticks, the whole end-to-end system is digital and either works or not, it cant really give these symptoms.
If you're able, try swapping the aileron & elevator pot connections & re-calibrate (you only need move the wiper wire, no need to move the 0v & 5v wires) - my bet is that the problem will move to your elevator channel. Although even touching a broken pot can upset it, or even fix it!
Sometimes the track can come loose inside a pot, so instead of the wiper sliding over the track , it moves the whole track slightly.
Three rivets retain the pot tags, the outer two also retain the track ends. The rivets can loosen and allow the track to rotate.
Sometimes on older pots the track can hairline crack which can have a similar effect. Or maybe the pot just needs a squirt of electrolube.
Typically we're using 50-year-old pots so this does happen from time to time.
Often within the stick unit, the plastic bale that grips the pot shaft cracks and loses tension, often through over-enthusiastic tightening. Shaun has suffered a few of these. But overall I'm 99.9% sure the electronics are ok and its a stick or pot problem
Cheers
Phil