40MHz transmitter "fix" ???

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I picked up another cheap RC car in a charity shop with a project in mind but I found my transmitters were not fully compatible. I remembered I had a non-working transmitter and wondered if it might be compatible if I fixed it. When I fixed it, it wasn't any better than the other ones but I do now have another working 40MHz transmitter.
Filmed using FujiFilm FinePix S4800
Edited using Serif MoviePlus Starter Edition
Here is the data sheet for the chip if you want to trace it out for yourself www.diodes.com...
PT8A977BP datasheet
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RX-3E data sheet
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Комментарии : 96

@hellcattanks 9 лет назад

I can throw some light on this if your interested. The 40 mhz radio signal is generated on the pcb separately to the control chip. The commands for for/rev/left/right are encoded onto a pulse train similar to that done in an old dial up internet modem, the data rate, or baud rate as you'd say for a modem is set by an internal oscillator within the control chip, pin 12 has a resistor connected to it that sets this datarate frequency. There is probably a mismatch in datarates between the transmitter and receiver as they are not from the same toy (they need to be the same), you are correcting this mismatch by putting the piece of wire on pin 12, hand capacitance or possibly feedback from the transmitters own aerial is forcing the datarate frequency to shift and match that of the receiver, the chip pair are designed so that they'll still work if they are mismatched by up to 4x.The manufacts provide this function as a low data rate increases range but slows down control response, and a high rate speeds up response and decreases range, for a single function toy you'd use a low rate as theres only one function.If you want to do this more scientifically replace the resistor in pin 12 with a trimmer 5x its resistance, then twiddle till it works.

@GrandadIsAnOldMan 9 лет назад

hellcattanks that might be worth a try, thanks.

@RCLoversan 8 лет назад

Wow! Super close to my best guess, without reading this comment first :-)

@JustFun-iz9rf 3 года назад

Glad it works. I was trying to find a variable frequency remote control or even a circuit so I could build it. No luck yet

@GrandadIsAnOldMan 3 года назад

If you google the TX2RX2 chipset data sheets they usually have example circuits, and some of them do include the requirements for the different frequencies. However I have never attempted to build one from scratch. This data sheet shows the workings of the chip nicely, but does NOT cover the RF circuit blog.tkjelectronics.dk/wp-content/uploads/2011/09/RX2_TX2_Datasheet.pdf

@HappyHermitt 2 месяца назад

@@GrandadIsAnOldManTX2B/RX2B.

@GrandadIsAnOldMan 2 месяца назад

@@HappyHermitt there are several variants of the tx2rx2 chipsets

@pjoskar1 4 года назад

You invented a universal remote for all rc cars you dont even know lol

@GrandadIsAnOldMan 4 года назад

I wish 😁👍

@AnkitYadav-pg6bv 5 лет назад

Hey, what should be the lenght of antenna if my RC car has 40 MHz frequency?

@GrandadIsAnOldMan 5 лет назад

This thread on an RC forum may help you, the comments point out that most RC gear has circuitry to change the actual length of antenna required so knowing the "correct" length may not be the answer www.rcuniverse.com/forum/rc-radios-transmitters-receivers-servos-gyros-157/8295524-proper-antenna-wire-length.html

@Coches-RC 6 лет назад

the analysis of an old Nikko transmitter (called Full function) is here: reparar-cochesrc.blogspot.com.es/2015/12/emisora-nikko-de-6-funciones-y.html

@GrandadIsAnOldMan 6 лет назад

Excellent link, thank you :-)

@hackerista4052 3 года назад

Hii, i have a question. My rc car is 40mhz nikko. But no remote. And I found 40mhz remote control same brand, but different type. Is it can use on my rc car?

@GrandadIsAnOldMan 3 года назад

I am not sure why you are asking. Surely if you have the car and you have the remote you have tried them together and know your answer without asking me. All I can say is it might work and you will find out when you try it. I have a box full of remotes I have collected. When I get an rc car I go through the box to see if I have a match. Sometimes I am lucky and sometimes I am unlucky. Sometimes I have to swap out the receiver for one that I have a matching remote.

@hackerista4052 3 года назад

@@GrandadIsAnOldMan thanks, how about 27mhz?

@GrandadIsAnOldMan 3 года назад

@@hackerista4052 you would need a matching 27MHz receiver and 27MHz remote, the same way that you need a matching 40MHz receiver and 40MHz remote.

@Coches-RC 6 лет назад

the analysis of PT8A977BP (tx-2b and rx-2b are similar) i.c. is here: reparar-cochesrc.blogspot.com.es/2015/12/codificador-y-decodificador-tx-2b-y-rx.html

@GrandadIsAnOldMan 6 лет назад

Excellent link, thank you :-)

@cjmanueldalimot2068 4 года назад

how far does the 40mhz controller take?How many Meters?

@GrandadIsAnOldMan 4 года назад

Do you mean this specific controller or 40mhz in general. The answer is the same anyway. It depends on the power of your batteries and the length of the aerials in both the transmitter and the receiver. Generally toy grade RC systems are only designed to work over 4-6 metres maybe 12 metres in a nice open area.

@miamifiction 9 лет назад

Hello. I'm fixing my old RC 1979 Custom Van, is already working, but the two servos that move the van right and left are missing. It seems one of my nephews was playing with it when I wasn't looking :/. Do you know of any toys or home appliances that work with small servos? Because in Radio Shack and other similar places they cost a lot :/. Regards.

@GrandadIsAnOldMan 9 лет назад

I buy my servos from China via eBay, they are really cheap. It just depends what you need. Here is a typical example www.ebay.co.uk/itm/261521757538 10 servos for £14.99

@miamifiction 9 лет назад

Well I'm not sure, the ones from my van were the size of a Peanut. No seriously, they had a small gear in one end. They work with 1.5 Volts each and together they act as one motor that move the front wheels in different direction, making the van go right or left. Thanks for the info, let me check the ones from Ebay. Regards and thanks again.

@miamifiction 9 лет назад

One more thing, you have very cool toys, I also have 4 remote control cars from the 80s. the oldest one is the van that I mention. Regards.

@quangngo3226 2 года назад

Can you help me how to connect Futaba T6XH 35mhz transmitter and receiver?

@GrandadIsAnOldMan 2 года назад

No I am afraid I cannot help you. I am not familiar with that system.

@techtinkerin 3 года назад

Lol at it was £1.50 but I got it for a quid.. it is a charity u know 😁❤️

@GrandadIsAnOldMan 3 года назад

Charity shops are an interesting concept that may be difficult to get your head around. They are a business that makes money and get's additional tax breaks from the government that puts them at an advantage over other businesses. Often staffed by volunteers, so their overheads are minimal in comparison. If you want to donate to the charity, you can always donate direct. A charity shop is a shop that sells stuff, it is not "the charity". My target price is £1 when I walk into a charity shop. I do pay more, but that is my target. Many of the charity shops have doubled or tripled their prices recently.

@Slider2732 9 лет назад

Yes, perfect for motor on/off on an otherwise free flight...an already very popular one that has wheels on it ;) RX-3E, connect a wire to Pin 2 lol Does Pin 6 of the other chip supply a 'Turbo' to the working car ?

@GrandadIsAnOldMan 9 лет назад

Yes you can see where my mind was going, it would switch off the motor as soon as it got out of range. I would have to up the power to carry the extra weight, but the benefit of not losing it would allow me to use a decent battery anyway. RX-3E pin 2, yes there is probably a way of using that effect to 'tune' the receiver as that seems to be what is happening with the transmitter. You might have noticed that initially it didn't recognise the 'reverse' direction signal from the transmitter but after the transmitter was 'fixed' it reacted to all 4 directional inputs. - although it went backwards in response to all of them. Turbo - I believe it would if implemented. Those faulty receivers I worked on a while back had the 'turbo' output but it was not connected to anything and I guess you would need to add a push button to your transmitter somewhere to send the signal. Probably an interesting project on it's own. Maybe not turbo, but some other operation like maybe fire a gun or flash a light or something.

@siyamsingh9b501 3 года назад

My rc car goes only in forward direction and little bit in backward Direction plzzz make vedio for that

@GrandadIsAnOldMan 3 года назад

First you would need to check there is nothing wrong with the gears. No teeth missing, no split in the gear allowing it to slip on the shaft. No hair or dust around the axle stopping it turning. If you have done all that, then the most likely reason for it going forwards and not backwards would be part of the "H-Bridge" circuit has failed. The H bridge is the part of the receiver circuit that sends power to the motor. Here is a video where I did some work on this problem ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-wIWNY1R5KZo.html and here is another one ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-5w7f2Fblo4k.html and another here ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-PdZJJi56Lu8.html

@siyamsingh9b501 3 года назад

@@GrandadIsAnOldMan but when i was inserted new batteries in remote , the car permof all activities but after some seconds the forward it is going only.....i have checked that all my motors of car working

@MrTvmediaman 7 лет назад

Hi i have a problem with my RC car. when i use the remote control nothing happens. The car doesnt want to work. The remote is 40Mhz and 9.6V. Can you please help me solve this problem.

@GrandadIsAnOldMan 7 лет назад

The usual problem is loose battery connections either in the car or in the transmitter. If you have another car with the same frequency transmitter you would be able to find out if the problem is in the car or in the transmitter 😊

@jeffbeck6501 7 лет назад

Some remotes have little adjustment places to tune the transmitter and receiver frequency. They are in both the transmitter and receiver. You need a tiny screwdriver for eye glasses to turn it. This is probably to let people run several cars on different frequencies.

@GrandadIsAnOldMan 7 лет назад

😊

@davidpuissegur1263 9 лет назад

Another great video! I'm just waiting for good weather to try and fly my SUPER CAPACITOR Micro airplane. What did you do for most of your working life? I guessing from this video that it was in the Electronics field. Please keep the educational videos coming!//////

@GrandadIsAnOldMan 9 лет назад

I hope you remember to get a video if your plane flies. I was a telephone engineer, nothing complicated.

@ichikosudo1054 9 лет назад

Did you ever make the radio controlled plane out of the receiver from this rc car? I have a tiny tiny receiver from a rc matchbox car that I don't know what to do with. It's about 1 centimeter by 2 centimeters in size.

@GrandadIsAnOldMan 9 лет назад

Ichiko Sudo the main problem with using this type of transmitter and receiver for a plane is the lack of range, probably only 3 to 5 metres so you would have to run after a plane to keep it in range. That is assuming you are capable of soldering the hair thin wires to connect the receiver to whatever you want to control. It is not an easy task.

@mianahmad5918 4 месяца назад

I have a 27 MHz toy car transmitter and there is no IC chip in it. Forward and reverse options with only 13 components, like resistors, capacitors etc. How does it work without any chip? Thanks

@GrandadIsAnOldMan 4 месяца назад

Are you sure there is no chip? It may be a black blob that looks like a lump of paint.

@mianahmad5918 4 месяца назад

I opened it for you today and there is no black blob there. The black blob, you are talking about, is used in Casio caculators. But there are no tiny chip. I can send you the pictures or a short video to you if you share me your email address. There are 3 transistors with "C9018" markings, 1 green inductor with striped lines. 5 ceramic capacitors with markings of 104", and an adjustable slug coil.

@GrandadIsAnOldMan 4 месяца назад

Why don't you just upload it to your channel?

@GrandadIsAnOldMan 4 месяца назад

It might be worth your time reading this article www.talkingelectronics.com/projects/27MHz%20Transmitters/27MHzLinks-1.html

@mianahmad5918 4 месяца назад

But I do not have a RU-vid channel. Thank you for your quick replies. I am learning this stuff from you.

@sk36kostahi16 3 года назад

BTW the wire method works because it uses it as an antena to send signals through

@GrandadIsAnOldMan 3 года назад

Not really, as I explain, I am attaching that wire to pin 12, which is the adjustment for the internal clock frequency. The antenna connects to pin 8 via the radio transmission circuit, so connecting a wire to pin 12 does not act as an antenna, the signal does not go to that pin. Here is the data sheet for the chip if you want to trace it out for yourself www.diodes.com/assets/Datasheets/PT8A977B978B978BL.pdf

@dka3288 9 лет назад

Can you make a hot air balloon and add your smallest motor thanks grandpa I'm Charles

@GrandadIsAnOldMan 9 лет назад

I will not be making one but for your information a motorised hot air balloon is know as a Thermal Airship en.wikipedia.org/wiki/Thermal_airship I consider free flying hot air balloons to be hazardous to other people and property because they carry a flame that could cause a fire. This is the only type of hot air balloon that I have made and you will see I use a hair dryer to heat it and keep it tethered so it does not blow away and cause a hazard to anybody. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-Bcllc3fBi6I.html

@OrganicGonzalez 5 лет назад

dude you are so creative. im new to the rc world I got a lot to learn

@GrandadIsAnOldMan 5 лет назад

I am afraid I am no expert, I just poke around and see what happens.

@soufi7356 9 лет назад

Great video!

@GrandadIsAnOldMan 9 лет назад

Thank you. I wish I understood how this actually works.

@قناهآندرويدللالعاب 6 лет назад

بعد اذنك عمو ازى تبدل الاريل

@GrandadIsAnOldMan 6 лет назад

I may have misunderstood you but I don't think changing the aerial would make any difference. The receiver gets the signal OK but it does not have the same features.

@alisongeffin156 7 лет назад

that's a really good idea

@GrandadIsAnOldMan 7 лет назад

Hi Alison, thanks but I would be happier if I knew how it worked. This is one of those accidental fixes where I was just poking around hoping to find something like a loose wire and noticed it started working when I touched a particular terminal on the controller chip. It is not what I would call a fix.

@anthonybelcher8569 6 лет назад

Awesome

@GrandadIsAnOldMan 6 лет назад

Thanks Tony 😊

@tymekrozanski123 9 лет назад

GrandadIsAnOldMan can you make a mini fan car with a pager motor and a mini car. can you use a cheap car and not make it your self

@GrandadIsAnOldMan 9 лет назад

I don't have any pager motors but the ones I take from the Oral B Pulsar vibrating toothbrush are a similar size. Here is one driving quite a large car ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-ysn4Xkm0b8k.html

@tymekrozanski123 9 лет назад

yes i meant them i though that was their name.

@tymekrozanski123 9 лет назад

GrandadIsAnOldMan could you make a really small one please

@GuitarRocks360 9 лет назад

you should make the Mickey Mouse (foward reverse) car's steering remotely functional. Would be nice.

@GuitarRocks360 9 лет назад

I never seen those type of RC vehicles have remotely operated steering.

@GrandadIsAnOldMan 9 лет назад

+GuitarRocks360 I could but it rather takes away the simplicity of the car. It is designed for very young children to play with so it has a very simple function, just forwards or backwards. To give it functional steering I would have to replace the receiver.

@GuitarRocks360 9 лет назад

+GrandadIsAnOldMan maybe someday you'll make an rc car 2.4 ghz

@GrandadIsAnOldMan 9 лет назад

GuitarRocks360 this one is 2.4 ghz ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-uM7Obu2wnKA.html

@tylerraines3451 9 лет назад

Can you do a rc car mod ? Or make your own rc car please grandad i would love to see a video like this

@GrandadIsAnOldMan 9 лет назад

I currently have 92 videos in my Radio Control playlist with cars and boats etc. ru-vid.com/group/PLA5a2xPRSrB13Xcquw4Ff09MQzTPjeVkI

@sirlipoldaru5941 4 года назад

Tere

@GrandadIsAnOldMan 4 года назад

@akarandom1 9 лет назад

Thank you for creating such awesome content

@GrandadIsAnOldMan 4 года назад

:-)

@spagetttheyett269 6 лет назад

"Reverse reverse revers fowards"

@GrandadIsAnOldMan 4 года назад

:-)

@Twinightforest 9 лет назад

Nice video as always.

@GrandadIsAnOldMan 9 лет назад

Thank you Muas

@anthonybelcher8569 5 лет назад

Great job

@GrandadIsAnOldMan 5 лет назад

Thanks Tony

@boowonder888 5 лет назад

Im back on the channel because Im diy ing my old love, an rc car. like I did in the mid 80s when I was young. I am bulding the steering out of Popsicle sticks. When I was 14, I wouldnt have thought of that, so I have progressed in all those years, lol!.

@GrandadIsAnOldMan 5 лет назад

Thanks for dropping by. Make sure we see a video of your projects 👍

@RCLoversan 8 лет назад

Antenna anyone? :-)

@GrandadIsAnOldMan 8 лет назад

If you mean that the wire I have added is replacing the antenna, no, you are wrong. I show you the circuit diagram and the pin. I believe it affects the carrier frequency of the radio signal.

@RCLoversan 8 лет назад

GrandadIsAnOldMan Ok, maybe I've been a bit hasty. Anyway, I've checked the diagram and pin 12 should be connected to a 200k resistor to pin 11. My best guess is the resistor placed on the pcb is damaged, hence a long wire works as a substitute. If you don't mind to try this experiment, (I mean, please don't blame me if it doesn't work), I would replace your wire with a 200k resistor between pin 12 and pin 11.

@GrandadIsAnOldMan 8 лет назад

RC Lover san Thank you. You might guess that as I have downloaded the pdf datasheets for the chips and included them in the video I might have already read them. Perhaps you might like to read some of the other comments. The one by Splitfire pilot (1 year ago) probably gives the best explanation and suggestion.

@RCLoversan 8 лет назад

I'd like to add another thing, regarding how transmitter sends commands for the direction. The controller has been programmed giving to every channel a specific range, therefore you can't change it. If you watch my video about how Arduino gets the signal from the Flysky FS-T6, you'll understand immediately how this thing works. Again, just for the sake of doing some experiments.

@GrandadIsAnOldMan 8 лет назад

RC Lover san I have watched many of your videos. Which one are you talking about?