Using RC Car Parts As Remote Control

I sourced a lot of micro RC cars at ebay to use them for DIY projects.
The cars are from Enertec. The call the product "MICRO FLASH CHARGER, Formula 1". The product box contains batteries for the transmitter and the charging box, the transmitter box, a charging box and the car. There are 27Mhz and 40Mhz versions of the product.
The control of the systems contains functions to drive forward, backward, left, right and to drive "turbo" forward. All these functions are not proportional.
The motor is mounted in a small gearbox and drives both back weals at once. For the changing of the driving direction there front weels can be pulled left ore right. this is done by small coils that pull a magnet to the left or to the right. The magnet is mounted on the guidance mechanic.

I was interrested in using the electronic for simple remote switching purposes. For this project I only need the two pcb's. The other parts, like the motors are kept for later projects.

Step 1: Analyzing the Circuit

The transmitter is the easy part.
The receiver is more complex. I need some switching outputs. The easy part are the two coils that change the driving direction. Fine copper wires are soldered to the pcb and lead to the coils. The two transistors that switch the coils carry the SMD code 1P. Searching around the internet I found out that these transistors are NPN of the type MMBT2222A. Thinking about standard switching circuits I assumed that the transistors are connected to GND with the emitter connections and that the coils are directly connected to VCC. Some measurement on the PCB confirmed that. Only thing to do ist connect some LED to the switching outputs.
Doing further reverse engineering I found out that the transistors marked 1AM are MMBT3904L. These transistors are connected via resistors to the receiver ic (BA97). The transistors are NPN types, but the emitter connections are not directly connected to GND. I decided to simply remove the rest of the transistors and use the 1AM as the switching outputs.

Step 2: What You Need

Material;
- One of the cars
- A resistor array. I used a 330Ohm SIL array fro man old floppy disc drive
- 5 LEDs, I used 5 yellow LEDs that I sourced from an old 100MBit switch
- Some wires, I got them out of an old video recorder
- Experimental PCBs, this ones I bought ;-)
- 5 bush button switches, I sourced them from an old video recorder
- 1 3V button cell battery, taken from an old pc mainboard
- 1 battery holder, also taken from the pc mainboard

Tools;
- pliers
- soldering iron
- desoldring pump
- regulated dc power supply (to power the transmitter)
- multimeter
- clips
- shap eyes
- a calm hand

Step 3: Modifying - the Transmitter

First of all I added the switches to the transmitter. The switches all switch to GND. Connection is straight forward. I used a small ex board and some bush buttons that I sourced from an old video recorder.

Step 4: Modifying - the Receiver

First of all I removed the unused transistors. After that I added the GND connection to each of the remaining 1AM. Then I added the wires for the power connection and soldered them to a 3V button cell battery holder. The wires for the LEDs where added and the LEDs aligned on a small ex board. I used a resistor array from an old floppy disc drive as the series resistors for the LEDs.
Soldering is a little bit tricky here, because there is not much space and my eyes are getting old .. and bad :-)
For the GND wires of the transistors I used tiny copper wires that are coated with insulating varnish.

Step 5: Result

You can see the whole setup in the picture.
The video shows how it works.

You can see that every key press leads to a lighted LED. But there is one exception. Pressing the turbo button simultaneously with one of the direction buttons, leads to a change fro mthe turbo led to the forward led. It seems that the RC car switches down a gear while driving a curve ... ;-)

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    33 Discussions

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    NaveedR5

    3 years ago

    Asalamalikum Dears,I have a lot of rc remotes and recivers but i have taken it from different toys ,can any body tell me can i use a differernt remote on different reciver.please guide me how i can channge it frequency,

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    jovnel

    3 years ago

    i have made an rc car but dont have a circuit and remote can u plzz help

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    PankajK3

    3 years ago on Introduction

    hi ....i m new Rc car owner .......my brother gifted me this car last year ......... i lost my remote and don't know frequency ..... i already checked all over but didn't written anything about this company and about anything .so please analyze this circuit and help me to buy new remote ..................pankaj


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    Christiantodd

    3 years ago

    Hello! I have a 27Mhz Radio Shack RC that also controls ONE function on my 6 year old Tyco RC. So, with only what 6 channels in the 27Mhz space, and each having only 6 functions each (I may be WAY off on those numbers I know) but why can't someone simply make a 'universal' remote that has all of those possible combinations? Those 2 toys were made year apart and have different crystals so the logic here makes no sense. I have several older RC cars with no remotes and this is driving me crazy! I really appreciate ANY thoughts here! Thank you... Todd

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    APSX

    4 years ago on Introduction

    Do you know if I can buy a semi-assembled RC car without the receiver and the transmitter. Or can I build from scratch from the base chassis? I just need the servo motors, the base and the tires. Any ideas?

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    SeanLynch91

    4 years ago on Step 5

    Are you able to light up the forward, reverse, left, and right LED's at the same time if you press all four of the corresponding switches down? Great project! I'm working on a project very similar to this, thanks for all of the insight!

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    Kaiven

    10 years ago on Introduction

    Is there a way to mod the circuit to use even more things (like leds?) on the receiver and transmitter? I want to add a third motor to my broken rc car, because I want to do a lot of modding. I don't know how to attach the third motor. All it has to do is spin.

    8 replies
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    frickelkramKaiven

    Reply 10 years ago on Introduction

    Hi, these simple circuits have 5 outputs. You can use them to switch leds but also to turn on small motors, that's what they are made for. Inside the car every output is used somehow. I described that in the Instructable. You can turn the car left, right, drive forward, backward and use the turbo. That makes 5 remote controlled functions. If you don't need one of these you can use it for other things. The only thing, that I can think of is the turbo. It is rather difficult to drive the car while using the turbo. Most of the time I avoid using it. If you use the turbo to switch on an other motor, keep in mind that the forward function is switched off when using it. You can see that in the video. Basically, I would say, it is not impossible but you are limited to the simple functionality of the system ...

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    frickelkramKaiven

    Reply 10 years ago on Introduction

    Hi,
    some cars don't use the fifth function, but the ones I know use chip sets that implement these functions. Tale the RX2C for example http://www.ausmicro.net/v3/thedump/00A9FF9700A9FF98.pdf . I found this in a non name rc car. In the old Super Rebound (Year 2000 edition, the 4-wheel drive) uses Yuniden Taiyo 97-1 chip set. This one also has a turbo function but it is not used in the super rebound. I can't remember the chipset of the small car I tore apart here, but I can try to find out. It uses a more modern chip set very similar to the popular RX2C chip set.
    Try to identify the chip set and search for the datasheet on the internet. If you find it you are able to find out what functionality can be used ...

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    Kaivenfrickelkram

    Reply 10 years ago on Introduction

    I think I might stick with buying a five/six function chip of the internet. Some guy on YouTube showed me where. I would just need to go find the link he gave me.

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    amando96Kaiven

    Reply 9 years ago on Introduction

    yea but u can use combinations of outputs... like right, back one thing left, back another thing then u'll have like 16 possible actions...

    i made one like this, but it moved a spy mini camera around it was neat but i took it apart coz i needed the bits.. :(
    i think i have it on youtbe though...

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    jackonhismac

    6 years ago on Introduction

    Hey i was just wondering if you replace the crystal from one transmitter into anther. Will it change the frequency?

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    casey321b

    10 years ago on Introduction

    from the looks of the car controller i could make a joystick with usb for my comp