Introduction: Using RC Car Parts As Remote Control

Picture of 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

Picture of 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

Picture of What You Need

- 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

- 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

Picture of 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

Picture of 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

Picture of 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 ... ;-)


NaveedR5 (author)2015-11-21

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,

jovnel (author)2015-09-24

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

PankajK3 (author)2015-02-10

hi ....i m new Rc car owner 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

Christiantodd (author)2015-01-18

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

APSX (author)2014-07-17

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?

SeanLynch91 (author)2014-02-17

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!

nanonano58 (author)2007-10-26

were do you buy that rc car ?

astral_mage (author)nanonano582013-09-21

check out then look up r/c cars uill be able find plenty of makers of them

frickelkram (author)nanonano582007-10-27

I bought a bunch of them on an eBay auction ... but they don't sell them on regular basis :-(

Kaiven (author)2008-11-22

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.

frickelkram (author)Kaiven2008-11-22

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 ...

Kaiven (author)frickelkram2008-11-22

every car I take apart only has 4 outputs :(

frickelkram (author)Kaiven2008-11-23

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 . 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 ...

Kaiven (author)frickelkram2008-11-24

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.

astral_mage (author)frickelkram2013-09-21

broken link

astral_mage (author)frickelkram2013-09-21

broken link

amando96 (author)Kaiven2009-01-28

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...

jackonhismac (author)2011-12-19

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

casey321b (author)2008-09-05

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

cotton (author)2008-04-16

so whats the point why not hoiork the car to a reley and have one button that trigers the relay to turn somethingon and keep it on then another button for a onother thing and then pres the button again so it turns off

stevoIution (author)2007-10-26

Good instructable. The first thing I do is put a drop of hot glue at the base of each wire so they don't snap off from handling.

gbosbiker (author)stevoIution2008-03-20

you can just solder it on well. it works much better with much less chance of the cord ripping off.

Whaleman (author)stevoIution2007-11-03

good idea.

frickelkram (author)stevoIution2007-10-27

It's a good idea to do that. It often happens that wires break because auf too much bending during examination .... thank's for the comment!

CyberBill (author)2007-12-28

Are there any other oddities in the transmitter with button combinations, for example left + right, or forward+backwards? Whats the range on these little guys? I really liked this instructable, it gives me a lot of ideas! :D

frickelkram (author)CyberBill2008-01-02

Hi CyberBill, there are no other restrictions that I know of. Turbo mode is the only one. Driving backwards there is not turbo mode, and therefore no restrictions ... :-) The distance is not very high. Basically the 27Mhz version has a wider range than the 40Mhz. Even the 27Mhz version has maximum of about 5 meters. But if you look at the construcions you may notice that the antennas are far away from being ideal! Getting better antennas on the transmitter and on the receiver side could extend the range. Other thing for optimization is the frequency of transmitter and receiver. These parts are so very cheap built that I am sure that you can get much better results if you trim the rf components a little bit. I think that the Chinese manufacturers do not adjust the components exactly, that takes time, and costs money. What for ... these cars do not need to work on a distance of more than 5 meters. They are build to be used in buildings. But I believe there is more potential in them. I already thought about making some tests but did not have the time, so far. But as soon as I get noticeable better range I will simply post an Instructable about how to do it ... :-)

James (pseudo-geek) (author)2007-12-02

great instructable, and great idea! (+)

Ohm (author)2007-10-27

I have seen people take the guts out of these cars and use them to make micro rc airplanes.

frickelkram (author)Ohm2007-10-28

You may expect some similar doings from me ... ;-) I'll post some of them here when I'm finished ...

Kaiven (author)frickelkram2007-11-03

i really can't wait :P

dan (author)2007-10-26

thanks for posting this. i did the exact same thing a while back, the whole system is very convenient for a $10 remote-control unit which can easily control a wide variety of stuff. if i recall correctly, the motor output transistors are connected in a standard H-bridge configuration, that allows the motor to be driven either forward or reverse.

frickelkram (author)dan2007-10-26

Hi Dan, yes, the circuit seems to be an h-bridge. The motor can be driven forward and backward. I had trouble analyzing the h-bridge layout, the pcb is far to tiny for my old eyes ... ;-) but I'll try again sometime, because I am very interested in the exact schematics of the car ... Because I bought a bunch of cars on ebay you can expect more instructables using parts of the cars in the future .... stay tuned ... ;-)

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