Project:

The Ultimate ATV Remote Control Car

Designer(s):

N8QPJ

Description:

The inspiration for this project came from a program on The Learning Channel. The program Documented the journey of a tethered robot up a shaft in an Egyptian pyramid. The goal of this project was to build a remote control vehicle to drive to my sister's house 1/3 of a mile away. I chose a remote control car chassis as the platform for the vehicle. To get the car ready for a drive, the first thing to do is turn on all the power switches, motor power, servos, camera power, HT and finally transmitter power. Check for a good picture and audio on the monitor. Turn on the controller radio. The car comes to life with a slight push on the throttle stick. I am driving the car down the hallway of the place I work. The cleaning crew is some where in the building. Suddenly two feet appear on the monitor. I stopped the car and tilt the camera up to see who it is. As they look down at the car with a puzzled look, I push a switch on the controller radio to activate my HT on my belt and out of the speaker on the car comes "HELLO THERE". The person (Marie) standing there said "CAN YOU HEAR ME"? I replied "YES I CAN." Marie walked away from the car, I followed. Marie walked faster, I followed. I saw Marie reach for light switch, the lights went out. No problem with ten high output infrared LED’s around the camera to light my way I continued to follow. Marie ran out the glass front door quickly closing it behind her. I brought the car to a stop inside the front door, tilted the camera up and looking through the glare of the infrared LED’s, I panned the camera to the right, only to see Marie smiling as she looked at the car shaking her finger. Oh well. I backed up the car, turned around and headed back to my office. This is just one of the many adventures I’ve had with the ultimate remote car.

Some Technical Information:

The platform for the car is a Traxxas stadium truck chassis. The mechanical speed control was replaced with an electronic unit. Increasing the gear ratio and adding a clutch disc along with the electronic speed control greatly increased low speed maneuverability, which is essential in tight places. The coil springs were beefed up to handle the extra weight. The R/C radio is a four channel Futaba 75 MHz unit with joysticks. The radio came with three servos, one is used for steering. The other two are used for camera pan & tilt. The fourth channel is used by the electronic speed control. The R/C radio receiver on the car was put in a copper box with a band pass filter on the antenna to help shield it from RF from the ATV transmitter. The camera is a 400 line black and white postage stamp size (1.25" x 1.25") with built in microphone and line level out. To see in the dark ten high output infrared LED’s are situated on the top and side of the camera. The ATV transmitter is a 915 MHz 1/2 watt AM unit with a 1/4 wave antenna affixed to the top of a one foot long #8 threaded rod. To talk through the car to someone I put a mini 440 MHz HT with external 3" speaker on the car. The power for all this stuff is supplied by three separate batteries. A 4.8V pack powers the R/C receiver and servos. The drive motor is powered by a 7.2V pack. All the other devices on the car are powered by a 12V 1800ma cordless drill battery. To make it legal I put my call sign on the back of the front skid plate with white stick on letters. To ID I tilt the camera down until the call sign comes into view.

Hardware:

• Kenwood 46AT 440MHz mini HT with CTCSS decode
• North Country Radio 900 MHz mini AM ATV transmitter with audio
• Futaba Conquest FM FP-T4NBF 75 MHz 4 CH. radio with 3 servos
• Traxxas Rustler electric show truck chassis with clutch
• Traxxas electronic speed control with reverse
• ATV Research 1200A Black and White Postage stamp camera with audio
• DeWalt 12V 1800ma cordless drill battery
• Radio Shack 3" speaker
• Many custom made parts by N8QPJ

Hardware Sources:

• ATV Research (800) 392-3922
• Traxxas (214) 613-3300
• North Country Radio (914) 235-6611
• Futaba (714) 455-9888
• Radio Shack
• Home Depot

Conclusion:

This project took a little over a year to complete. I learned many things during the construction process. To name a few, dealing with multiple receivers and transmitters in the same package along with the interference that goes with the RF, modifying existing hardware to do what I want it to do and controlling an R/C car by watching a TV screen. Controlling the car by watching the TV screen is allot easier than trying to watch the car and steer.

The greatest satisfaction I get out of the this project is the reaction I see on the faces of people at club meetings when I demo the car at the end of an amateur television presentation. The car is definitely a big hit at the meetings

- Jeff Basting N8QPJ

Fig 1.0 - "The ATV car"

Fig 2.0 - "Received transmission from the ATV car"