3h. For the steering servo, use the
straight lever arm. Drill a small hole
in the lever arm the diameter of a #4
screw. Use the #4 screw, 2 washers,
and two #4 nuts to loosely attach your
modified tie rod to the servo lever arm.
Now, as you drive the car over rough
terrain, the servo will still be able to
steer the front wheel even as the front
suspension moves up and down.
4. INSTALL THE R/C RECEIVER AND WIRELESS CAMERA
4a. You can use just about any R/C
transmitter/receiver set for this project.
If you don’t already have a set, shop
around for a good deal. I found a great
deal on a 4-channel radio system kit
that included the transmitter, receiver,
and 1 servo for $60.
The reason I chose a 4-channel dual
stick transmitter (rather than a 2-
channel pistol-type transmitter) is
because I needed the second left-to-right stick to pan the camera.
4b. Using double-sided tape, attach
the receiver to the top of the steering
servo. To reduce the receiver’s bulkiness, remove its cover. This allows you
to easily install frequency crystals and
plug components into the receiver.
4c. Plug the camera servo into channel 4, and the steering servo into channel 1. Plug connection JP1
of the motor-control circuit board into channel 3 of the receiver; this connection will supply power to the
receiver and allow you to control the speed of the motor via the PWM signal generated from the PIC12F683
MCU. Make the PWM signal cable by crimping the male S connector’s pins to the bare-wire end of the male
servo cable using a pair of pliers. Now, in order to reduce electronic noise interference, loop the PWM cable
through a ferrite ring before plugging it into channel 3 of the receiver. This ring will increase the cable’s
inductance, thereby filtering out high-frequency electronic noise.
!
CAUTION: When using R/C transmitters and receivers for cars, keep them in the R/C car frequency
range of right around 75MHz. R/C airplanes operate right around the 72MHz frequency range.
Make: 103
