Thread Tools
Jul 30, 2020, 12:17 AM
Modelist
Alexandr1's Avatar
Quote:
Originally Posted by Finnspeed
If I used this kind of system in an expensive plane, I would do the following: Use a genuine Futaba/JR/Spektrum (whichever quality brand you prefer) wire from the ESC to RX directly but connect only minus and plus wires to the RX and ESC. Then connect the Altis device normally between the ESC and RX. This requires soldering the extra power wire (plus and minus) to the ESC and obviously one free channel slot in the RX. This arrangement effectively doubles the power wiring from the ESC BEC to the RX and also minimizes the number of contacts & crimps via the added power wire. After this modification, any of the joints in the Altis device can fail without causing a total loss of power to the RX.
Yes everything is correct!
In my photo you can see two wires from the ESC, one is longer, with two wires + and -, to the receiver. Second shorter wire to Altis, and from him to the receiver
There were no failures under this scheme!
Last edited by Alexandr1; Jul 30, 2020 at 08:28 AM.
Sign up now
to remove ads between posts
Jul 30, 2020, 01:00 AM
Registered User
Aaro's Avatar
Hi
Thank you Joe and Risto for your informative posts. For those wondering how to make the mentioned bypass , a most simple schema is attached. There are many, many other splendid ways to do the trick of course. The other picture shows the actual implementation from some of my gliders.

Aaro
Jul 30, 2020, 07:55 AM
Registered User
eitanro's Avatar
I thought that you need to have ground wire as well... aren't you risking having a ground voltage offset?
Jul 30, 2020, 08:35 AM
Registered User
Aaro's Avatar
What in earth is such offset?

Quote:
Originally Posted by eitanro
I thought that you need to have ground wire as well... aren't you risking having a ground voltage offset?
Jul 30, 2020, 08:37 AM
Registered User
Quote:
Originally Posted by eitanro
I thought that you need to have ground wire as well... aren't you risking having a ground voltage offset?
In his diagram the Altis is grounded through the receiver.

The Altis is supposed to pass both V+ and Ground so it shouldn't matter if one or both sides are connected. To be honest I think most people are having problems with the connectors as the vast majority of people pull from the wires. Even a properly crimped connector doesn't have enough strain relief to tolerate that. Goop or hot glue is your friend here, just a hint.

Joon
Jul 30, 2020, 12:07 PM
Registered User
eitanro's Avatar
Quote:
Originally Posted by Aaro
What in earth is such offset?
I think that the right term is "ground lifting", I'm not sure that that's the case here, but if it can happen in this case, it can corrupt the PWM signal

Eitan
Jul 30, 2020, 02:13 PM
Registered User
Aaro's Avatar
Ok the theory is there. In practice, think a while the normal way of using the logger, pulling all the power through it, from ESC to RX and forward. A separate and different grounding potential would require that there is eg. some resistance in the ground line in that case; and in that case part of the power would turn to heat, and, I could quess, AMRT manufacturers would state something about the maximum current allowed, AMRT:s would get hot if a servo is stalled and so on. I wrote "would", as now such recommendations or spesifications do not exist at all. Just connect and fly. In receiver end, at least with JETI, all the ground pins, as well as VCC pins, are also together in a very binary and pragmatic way.

Anyway, I have not thought that at all as it has been enough for me to just measure the connection (gnd-gnd and plus-plus over the AMRT). They are galvanic --> the equal or equal enough ground potential exists everywhere in the circuit.

Aaro

Jul 30, 2020, 07:31 PM
launch low, fly high
As the Altis by itself uses nearly zero current, the system that Aaro shows will result in the same ground voltage for the Altis as the receiver. Of course, this may be a different ground voltage as compared to the ESC if there is sufficient current between the ESC and the receiver, although that problem exists regardless of whether one has the ground and hot wires connected on both sides of the Altis. I have the connections on both sides of the Altis as well as the hard-wired bypass for power and ground. It would be highly annoying if the Altis reset in flight due to a bad connection via the single plug...
Jul 30, 2020, 08:25 PM
D T
D T
Registered User
D T's Avatar
Quote:
Originally Posted by Joe W
As the Altis by itself uses nearly zero current, the system that Aaro shows will result in the same ground voltage for the Altis as the receiver. Of course, this may be a different ground voltage as compared to the ESC if there is sufficient current between the ESC and the receiver, although that problem exists regardless of whether one has the ground and hot wires connected on both sides of the Altis. I have the connections on both sides of the Altis as well as the hard-wired bypass for power and ground. It would be highly annoying if the Altis reset in flight due to a bad connection via the single plug...
Could you please draw a diagram on how you did your wiring?
Much appreciated.

DT
Jul 31, 2020, 08:03 AM
Screwing up is an art
mabrungard's Avatar
Quote:
Originally Posted by Joe W
I have the connections on both sides of the Altis as well as the hard-wired bypass for power and ground. It would be highly annoying if the Altis reset in flight due to a bad connection via the single plug...
OK, Joe. Are you saying that your configuration is identical to the diagram that Aaro shows above, excepting that you also include the power and ground wires where Aaro shows only the signal wire?
Jul 31, 2020, 03:34 PM
Risto Hölttä - F3A/P Team FIN
Finnspeed's Avatar
Thanks Joe W for the kind words!

As I stated above, my recommendation would be to just add a separate power/ground wire (signal removed) between the ESC/BEC and RX. Aaro's suggestion works of course but again depends on a single connector for RX power which is totally OK if the connector and crimps is of high quality. There will be no ground loop or level issues either way since the Altis only consumes a few milliAmps.

The down sides of my suggestion are that you would have to solder the wires to the ESC directly and you would need an empty channel slot in the RX to connect the additional power wire.

Edit: Alexandr1 above seems to have made the same conclusions as I and is using the same wiring method.
Jul 31, 2020, 03:48 PM
Modelist
Alexandr1's Avatar
Absolutely right)))
Jul 31, 2020, 08:02 PM
Registered User
Why not just get rid of the connectors and hard wire?
Aug 01, 2020, 07:53 AM
Registered User
Hi Finnspeed

This is a very alarming discussion. I have always believed crimped connectors to be extremely reliable? This bias may stem from F1A days - the electronics engineer who manufactured the most popular flight processor for servo driven F1A models had the following as his number one advice to users:

Always use crimped connectors. Never solder your connections. The solder wicks up the wire and makes it brittle. A brittle solder connection will ALWAYS fail eventually.

On my PlusX, I deliberately avoided soldered Deans or MPX plugs, in favor of crimped connectors (using 3 x 6 PCB housings) - should I reconsider?

Maybe this is confirmation bias, but this has been my experience over the last 10 years. I have never had a failure with a crimped connector - the only failures have been solder connections - mostly to Lipo battery leads, even though I never pull on them, there is always movement whilst connecting/disconnecting. By pure luck, rather than knowledge or design, I have always cut the connectors off the Altis to adjust the lead lengths to suit the model. and replaced them with the keyed Futaba type connector using gold plated crimp pins obtained from Hansen Hobbies. Maybe I have been lucky, and the Hansen Hobbies crimp pins are high quality - different from the connectors on the Altis?

I would be grateful for your opinion on this. Do you see the issue as due to the poor quality of the crimp connectors in the Altis, or that crimp connectors themselves are not reliable?

(PS: Based on a faith in crimped connectors, I also run a 500mAh 1s Lipo backup system using a cheap Schottky diode per Kevin Caldwells excellent thread on the subject. I am surprised that this seems out of favor now. It has definitely been worth the effort - saved a model twice for me ( a failed battery solder connection, and an XT60 which unplugged itself in flight). Interestingly, my latest model has 6 X08 servos rated 3.5v, and 2 X10 minis, rated for 6v minimum. To my surprise, the 3.8v after the diode still drives them all for several minutes, the X10s included! The X10s only begin to jitter after about 4 mins, the X08s keep going much longer. (Of course theory says it will never work, stalled servos etc etc, but reality seem quite different - more than adequate for carefully returning home after a transmitter warning that your voltage has dropped to 3.8v) Thank you Kevin :-)
Last edited by murne; Aug 01, 2020 at 08:12 AM. Reason: Clarification


Quick Reply
Message:

Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Mini-Review Aerobtec Altis Nano AMRT for ALES/F5J gdouglas Electric Competition Soaring-F5J/F5K/ALES/E-Soaring 46 Jul 01, 2019 07:15 AM
Discussion Altis v4 andersgj Hand Launch 3 Oct 16, 2015 06:27 PM
Discussion Altis v4 Altitude Switch dharban Electric Competition Soaring-F5J/F5K/ALES/E-Soaring 24 Apr 26, 2014 08:26 PM
Help! Altis v4 rev.iain Electric Competition Soaring-F5J/F5K/ALES/E-Soaring 2 Jan 09, 2014 10:20 AM
Discussion New Firmware v4.8 with new PH and RTH photronix Aerial Photography 0 Mar 05, 2013 04:56 PM