Using transistor-like component to open and close multiple cables

Hello,

I am just a hobbyist and I am fairly new to electronics. I am building an autonomous model airplane.

I want my servos to be controlled by my ardunio board. However, I want to take over the controls using another rc remote. You see, my servo should be connected to the rf receiver and ardunio. I want to cut off the connection of the ardunio using a channel of rf receiver and I want the connection to be cut physically not from the code so it will be card malfunction safe.

I thought that I can use a lot of transistors and can cut off the receiver connection by connecting rf output to every transistors base but it is a lot off cable. How would you recommend I do this. All input is much appriciated

How will the other RC remote be able to control the plane?

Paul

Bus driver?
https://www.onsemi.com/products/standard-logic/buffers/mc74vhct541a

Paul_KD7HB:
How will the other RC remote be able to control the plane?

Paul

Rc Receivers are designed to control servos without any electronic components in between. They are basically configuring the pmw of one pin based on lets say how much you open the throttle or any channel for that matter.

I want my servo to be connected both to this receiver and ardunio board. I should be able to switch between them based on one digital output. Let’s say, when channel 7 of my RC receiver is HIGH (5V), only the receiver to servo connections should be closed and ardunio to servo connections should be open. When is Low (0V), vice versa.

I could not find any stores that sells those or any octal buffers in my country, an alternative maybe?

Since microcontrollers are far more reliable than RC radio links, I'd expect you to want the Arduino to be
in charge so that if the radio link drops out it can take back control, for instance should you go out of range
or if the battery level is detected as low.

Expecting the RC link to have ultimate command authority is asking for trouble.

isaturk:
I could not find any stores that sells those or any octal buffers in my country,

Why octal? Quad buffers include the 74HC125 and 74HC126. You don't NEED High speed CMOS (HC) types, you might be more able to find LS versions etc.

AJLElectronics:
You don't NEED High speed CMOS (HC) types, you might be more able to find LS versions etc.

It's not the speed.

74LS series is essentially obsolete - and should be. 74HC (and variants) drive rail-to-rail with much better and symmetrical drive capability. This is what you need in the vast majority of situations. The odd logic levels of 74LS are likely to cause many problems. :cold_sweat:

Paul__B:
It's not the speed.

74LS series is essentially obsolete - and should be. 74HC (and variants) drive rail-to-rail with much better and symmetrical drive capability. This is what you need in the vast majority of situations. The odd logic levels of 74LS are likely to cause many problems. :cold_sweat:

Maybe so, but he said that he had trouble finding any, so LS are likely to be found whereas HC might be more difficult. As an aside, the HC don't even appear in the libraries of the PCB programs that I have been looking at!

MarkT:
Since microcontrollers are far more reliable than RC radio links, I'd expect you to want the Arduino to be
in charge so that if the radio link drops out it can take back control, for instance should you go out of range
or if the battery level is detected as low.

Expecting the RC link to have ultimate command authority is asking for trouble.

You are definitely correct, ardunio is far more reliable. However, I am not. You see, I am trying to make a flight controller capable of autonomous takeoff, enroute and landing. I am a beginner on mechatronics so my Arduino circuit can malfunction not due to the unreliable hardware but my programming or wiring. I want to take control and save the hardware in case thing go south.

I was able to find some 74HC variants online. Can someone explain what is the function of these things?

AJLElectronics:
Maybe so, but he said that he had trouble finding any, so LS are likely to be found whereas HC might be more difficult.

I find that absurdly improbable. :cold_sweat: Perhaps dealing with "disposals" or "surplus" vendors. :grinning:

AJLElectronics:
As an aside, the HC don't even appear in the libraries of the PCB programs that I have been looking at!

Really? You must have an interesting choice of antiquities! :astonished:

isaturk:
I was able to find some 74HC variants online. Can someone explain what is the function of these things?

https://forum.arduino.cc/?topic=687167#msg4623295

Paul__B:
I find that absurdly improbable. :cold_sweat: Perhaps dealing with "disposals" or "surplus" vendors. :grinning:

No idea, but I would imagine that is some communist countries that all sorts may be restricted. However, your scenario is probably closer to the truth.

Paul__B:
Really? You must have an interesting choice of antiquities! :astonished:

I accept that I am very much new to PC PCB packages (I cut my teeth on RISC PCB) but I have tried Eagle, Kicad and the RS components one. None of them appear to me, to know what a 74HC126, a TH3122 or an MCP2025 is. All those design tools leave me completely cold in terms of user friendliness, so I am happy to be corrected and guided towards the goal.

Can we stay on point ?

I just linked a "generic" bus driver as a possible solution, that was the first that popped up on a search for "ttl bus driver", not meant as the best or only solution. I haven't done any "bus logic" work in too many years.

ballscrewbob:
Can we stay on point ?

Might that not be out of character here? :roll_eyes:

AJLElectronics:
Maybe so, but he said that he had trouble finding any, so LS are likely to be found whereas HC might be more difficult. As an aside, the HC don't even appear in the libraries of the PCB programs that I have been looking at!

74LS is obsolete (and has been for over 20 years) and its more expensive, less capable and cannot run at 3.3V.

74HC series has been current for ~30 years, in fact its becoming obsolete as 3.3V becomes more normal,
74LVC and 74LCX are perhaps the go-to logic families these days, being 3.3V with 5V tolerant inputs.

Since the pinouts don't depend on the actual family PCB software doesn't have to add new entries for every
device in every family, there are literally dozens of 74XX families out there. Look for 74XX in the list, not 74HC

Thanks for the info Mark, appreciated.

Would a 4019,
4-pole, double-throw data selector
be helpful here?

herbschwarz:
Would a 4019,
4-pole, double-throw data selector
be helpful here?

Obsolete part, does not appear to have a 74HC version! :roll_eyes: