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View Full Version : Inconsitant range and unable to drive slow


Inferius77
2017.07.02, 12:08 AM
I bought my first Mini-Z about a week ago and have used it almost every day. I am blown away by its quality. It's a perfectly tuned machine. I bought a MR-03 VE Pro MM2 Chassis, with a La Ferrari body and a KT-18 transmitter.
I have 2 questions relating to radio transmissions:

1.) After unboxing, pairing them together, and other first-time set up stuff, I began driving. The first thing I noticed was the lack of being able to drive slowly. By the way, my comparison is my experience with Xmods. On the xmod transmitter I could pull the trigger as light as I could and the motor would accelerate as little or as much as I pulled. With the KT-18, when I pull as little as I can, it doesn't do anything. And furthermore I need to keep pulling the trigger a significant amount more before the motor replies at all. The lowest speed I can get the car to go is so much faster than what I would consider "slow".
I haven't researched this too much. But I'm still open to any info that can be provided to me.

2.) I'm curious about my range. Now first of all I understand that this car is not meant to be used outdoors or out on pavement. However, two tennis courts I go to are very pristine, and perfect for driving on. I hate typing a lot of content but I kinda have to tell a story. I went to Court #1 one day, and it worked fantastic. I would send the car out, crossing three tennis nets. It never cut out at all as far as I saw. The time of day was about 6 or 7 pm. The next day, I went to court #2. This court is smaller. Like one third the size. Here's what really confused me. When I drove my car on this tennis court, reception cut out very close to me. I'm really bad at measurements, but if I had to guess I'd say 20 feet away it would start cutting in and out. The time of day was about 1pm. Later this day around 10pm, I tested the car with a second person. She held the controller and stood at point A on a straight street. I walked down the street a far amount (a little bit farther than the car went on court #1), and called for her to floor it for 7 seconds while turning back and forth. The test was flawless, no cutting out at all. I was really impressed cuz that was really far. (repeated the test twice more, went fine). So that's why I'm so confused. Why would it lose connection 20 feet away earlier in the day but then work like 100 ft+ later? Yes Batteries were always fresh, and even tried different sets in both devices. Was it perhaps sunlight? UV rays don't mess with signals do they? Just let me know what you guys think.

Check out my other topics of my current concerns here:
http://mini-zracer.com/forums/showthread.php?p=464061#post464061
http://mini-zracer.com/forums/showthread.php?p=464062#post464062
http://mini-zracer.com/forums/showthread.php?p=464064#post464064

arch2b
2017.07.02, 10:15 AM
there are some threads discussing the linear response of brushless motors. i only have one and rarely drive it these days as i prefer brushed myself. my thoughts would simply be retelling of things i've heard or read vs. experience thus will leave that one to the more knowledgeable.

as far as the transmitter, my theory is it's due to the transmitted running on 4 AAA. older transmitters run on 8 AA so the overall voltage is much higher. i'm not an electronics guru thus not entirely sure voltage = signal strength but i could run a mini-z farther than i could actually see it with the older radio's, even in the AM frequency days. i find even my EX-6 gets finicky below 4.5v and freshly charged NiMH only get you 4.8-5.6v. it's for this reason i've been contemplating upgrading the battery to Lipo for the transmitter. I can somewhat understand the move to 4 vs. 8 cells in transmitters but it seems it also handi-caps them? if you have access to a 5-UR transmitter, do some testing with that as it runs 8 cells. perhaps someone who understands the internals could comment as to if the transmitting power has also been reduced regardless of cells powering it?

Inferius77
2017.07.02, 01:43 PM
That's is certainly an interesting guess. I don't have access to other transmitters, but I'd probably upgrade to one if this thread or another thread determines it to be more efficient. Hopefully someone else does chime in with their knowledgeable opinion.

arch2b
2017.07.02, 01:45 PM
ask around locally if someone has an 8 cell transmitted you can borrow.

Inferius77
2017.07.06, 11:14 AM
I wish I could, but I can't find anybody who owns a Mini-Z except my cousins whom are very busy. I havnt been able to see their Mini-Zs however I do know they were purchased around the year 2006

TheSteve
2017.07.06, 12:08 PM
Transmitter voltage most certainly has nothing to do with range with a 2.4 GHz system. Unless of course you're below 3-3.5 volts. At that point the transmitter would let you know it is a problem.

The range issue was most likely caused by local interference. The MiniZ's use the 2.4 GHz band which is packed with other traffic. The other possibility is that the transmitter and car didn't sync up properly when switched on. Powering both off and then on would reset that.

The brushless motors used in MiniZ cars are of a sensorless design. Because of that it is very tough to start the motor smoothly and also drive the car at a very low RPM. To give the cars better starting the common approach is to up the start power and minimum speed. That is why you will never be able to creep along as you could with a brushed motor car.

arch2b
2017.07.06, 01:04 PM
good to know however doesn't align with practical experience (in my case). i simply cannot use my EX-6 when it drops below 4.5 as steering input becomes erratic, well before the low battery warning. i don't recall this ever being a problem on the 5-UR for example which has 8 cells or the EX-10. i'm not an electronics guru so just speaking from practical experience. could be i just have a bum transmitter as well.

wish i knew more of the science behind the various bands to know more about band saturation and congestion. with just about everything communicating wireless now, it's bound to do something. we already know the KT-18/19 has issues with congested areas.

TheSteve
2017.07.06, 01:42 PM
That would likely come down to poor design of the EX-6. The internal electronics might have a problem with the analog to digital converter used to sense the position of the steering potentiometer when the voltage is low. That would be independent of the transmitter portion which will be fine to a lower voltage.

arch2b
2017.07.06, 02:48 PM
interesting. perhaps this is one of the improvements of the EX-RR/EX-6R

Inferius77
2017.07.06, 10:13 PM
The range issue was most likely caused by local interference. The MiniZ's use the 2.4 GHz band which is packed with other traffic. The other possibility is that the transmitter and car didn't sync up properly when switched on. Powering both off and then on would reset that.

TheSteve, thanks for further input toward my concern. I'd like to comment on your thoughts here in the quote. When I began driving on tennis court #2 and my car was barely making it 30 feet without losing connection, I did think about what could be interfering. but the court is surrounded by woods, and there were no houses in sight at all. No routers/WiFi, no nearby cell towers, no electricity on the court. Nothing could have interfered except my cellphone. Furthermore, a powercycle did not fix it. When it began losing connection I tried replacing batteries in both car and transmitter. Therefore they were both power cycled. Also I turn on the transmitter first then the car, then power off the car first then the transmitter.

TeeSquared
2017.07.07, 12:40 AM
Have you tried re-binding the car rather than just turning it off and on again? Is the range issue a problem wherever you drive it?

The only other thing I can think of is perhaps there is something about the surface of the tennis court that the radio doesn't like.

TeeSquared
2017.07.07, 12:45 AM
Should have read a little more carefully. It seems like the problem is location specific. Could be an unseen 2.4 GHz device nearby as TheSteve suggests, or perhaps there is a big sheet of metal under the tennis court.

Inferius77
2017.07.07, 04:12 PM
or perhaps there is a big sheet of metal under the tennis court.

Another thought I had was perhaps the metal chainlink fence built high around the court was messing with signal?

TeeSquared
2017.07.07, 04:36 PM
A chainlink fence has openings very close to the wavelength of 2.4 GHz so its possible it creates an ugly RF environment. I'm really not too sure though.

I am assuming that the other two locations are not surrounded by chainlink fences?

Inferius77
2017.07.08, 03:14 AM
I am assuming that the other two locations are not surrounded by chainlink fences?
Court #1 is also surrounded by the same kind of fence. However the straight street had no fence around it. Court #1's range is better than court #2. Maybe it's cuz 2 is less than half the size of 1's. My friend and I testing the range in the street proved by far better than on the courts. The range was able to be double the distance without losing connection during 7 second acceleration.

KWT
2017.07.23, 12:14 PM
good to know however doesn't align with practical experience (in my case). i simply cannot use my EX-6 when it drops below 4.5 as steering input becomes erratic, well before the low battery warning. i don't recall this ever being a problem on the 5-UR for example which has 8 cells or the EX-10. i'm not an electronics guru so just speaking from practical experience. could be i just have a bum transmitter as well.

wish i knew more of the science behind the various bands to know more about band saturation and congestion. with just about everything communicating wireless now, it's bound to do something. we already know the KT-18/19 has issues with congested areas.

The EX-6 has settings for different types of batteries. If you set it to the correct one, it will give you a low voltage warning at the correct level.

arch2b
2017.07.23, 01:55 PM
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