Hacked $10 RC Car

erco

Senior Member
Walmart sells this New Bright car for $10. Cut one trace on the PCB to disconnect radio, then tap into 4 H-bridge connections for forward, reverse, left & right. My latest 08M2 project for a series in SERVO magazine does a Figure 8 here.


And a quick PWM demo for motor speed control: https://www.youtube.com/watch?v=8NaTCHR8Apg
 
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erco

Senior Member
Stationkeeping using a digital IR Obstacle/Proximity sensor.


Code:
do
b0=0 ' accumulator
for b1=1 to 50 ' loop 50 times
if pinc.3=1 then inc b0 ' increment b0 if sensor sees nothing
endif
next
if b0=0 then low 2: pulsout 1,4000'  100% triggered, reverse
elseif b0=50 then low 1:pulsout 2, 5000' 0% triggered, forward
endif
loop
 

jims

Senior Member
Erco...I've never done a robot project and this intrigues me. I've done quite a bit of programming with using an IR "clicker" to control functions (pumps, heaters, lights, LED strips, etc) with various Picaxe chips. Do you think this "hacked Walmart car" would be a good project to get into the robotic world? Thank you, JimS
 

erco

Senior Member
I think this is a good intro project. It's part 4 of a PICAXE Robotics series I wrote for SERVO magazine, it should be out ~ Nov 20 or so. My goal was to pick easy enough projects for beginners that are fun and achievable. This car project was simple but engaging. It ended up better than I hoped in terms of showing basic electronic hacking skills (disabling the car's radio control receiver, and tapping into the existing H-bridges) and programming a Picaxe 08M2. PWM (just one channel on the 08M2) is used on one H-bridge, and the IR proximity sensor can also receive commands from an IR remote control.

In Part 5 (~Dec 20) we will build a more traditional differentially steered robot, again using an 08M2. With a bit of luck, it may balance too, if the alkaline cells can keep up with the servo current demands.
 

jims

Senior Member
Thank you Erco.. I'll get parts to try this. Question??? What IR proximity sensor do you use? Thank you, JimS
 

erco

Senior Member
Excellent. The sensor can be had on Ebay for under $2. It has four connector pins and a rectangular black IR receiver module, such as http://www.ebay.com/itm/For-Arduino-New-Infrared-IR-Sensor-Obstacle-Avoidance-Sensor-Smart-Car-/400786755690 Also shown in the video in post #6.

Edit: Fun facts about that "KeyesIR" obstacle/proximity sensor. The IR receiver module is an odd duck. It is the rare "continuous signal compatible" type (good), and its gain is fairly low (bad). There is an onboard 555 timer oscillator which sends out continuous unmodulated 38 kHz-ish IR pulses. Nearby objects reflect the outbound IR pulses back to trigger the active-low receiver, indicated by the 'Sled' SMT LED lighting up. The module has 4 pins: ground, +5V,OUT, and ENable. ENable lets you turn the 555's IR output on & off. Ignore the ENable pin, and leave the ENable jumper on. OUT is simply the output from the IR receiver module, so it can also receive standard IR remote codes (IRIN /SIRC protocol) when the 555's signals are not being reflected by any nearby objects.

Edit #2: I forgot that I made a video about this sensor last year: https://www.youtube.com/watch?v=M5iMpUZo9AA
 

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OLDmarty

Senior Member
Excellent. The sensor can be had on Ebay for under $2. It has four connector pins and a rectangular black IR receiver module, such as http://www.ebay.com/itm/For-Arduino-New-Infrared-IR-Sensor-Obstacle-Avoidance-Sensor-Smart-Car-/400786755690 Also shown in the video in post #6.
Hi Erco,
4 years later, and i'm looking to buy some of these 4pin sensors to tinker with. Better late than never ;-)

I notice the most popular ones these days (2019) are only 3 pin, which use an LM393 (comparitor) instead of a 555 oscillator to drive the IR driver LED.
Maybe these aren't as good/sensitive as the 4pin types???


Edit #2: I forgot that I made a video about this sensor last year:
You mentioned the reflection panel (adhesive perhaps?)
What is the reflection product called? "Scotch-Lite" or a link to where to buy it please?

I think it's the Silver/fluorescent type refective tape, but hard to tell in your video.

Thanks for your tinkering and sharing with these little toys ;-)
 

erco

Senior Member
Vehicle update for anyone wanting to hack an RC car like this. Good news/bad news.

New Bright changed their PCB & circuit design a year or more ago. The discrete H-bridges are long gone, so the info above doesn't apply. The new ICs are proprietary and difficult/impossible to hack. On the bright side, you can buy an MX1508 dual H-bridge for just a dollar or two on ebay: https://www.ebay.com/itm/273757254762 My previous comments and that article only used the H-bridge portion of the original PCB anyway.

Info on the MX1508 at https://www.instructables.com/id/Tutorial-for-Dual-Channel-DC-Motor-Driver-Board-PW/ and truth table attached.

In a related story, Walmart has new $10 RC vehicles (their own house brand "Adventure Force") which are a great hacking candidates. Photos attached. These have several noteworthy improvements over the original New Bright vehicles (which are getting scarce anyway):

1) the Adventure Force (AF) vehicle assortment uses a modern 2.4 GHz radio control system (no external antennas) whereas the New Bright (NB) vehicles use decades-old 27 and 49 MHz radios with clunky external wire antennas. Even if you remove the PCB and use just the mechanical chassis, save the RC system for a future project.
2) the steering mechanism in AF vehicles has better torque and steering range than NB vehicles, although one of mine was assembled wrong and needed to be fixed.
3) the AF PCB uses a SMT (WAIT FOR IT!) MX1508 dual H-bridge! Yes! You could tap into the inputs and connect your micro to the PCB.
 

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