RC Helicopter Remote Control Circuit

The post discusses a simple RC helicopter remote control circuit using 433kHz RF modules, without any microcontroller or complex joystick implementations.

The idea was requested by Mr. Jitendra.

Circuit Objectives and Requirements

1. I am making a large scale RC helicopter. In which I am using 4 motors. For 1st main 12v motor: the mechanism is that I want its speed to be controlled by a controller key on the remote, from 0 to full speed.
2. For 2nd 3v motors: its mechanism is only for forward and reverse rotation with individual key on the remote for each motors as it will operate the swash plates of rotors.
3. For 3rd 9v tail motor: it should be set to an equilibrium speed using a regulator on the receiver board of helicopter so that I could adjust the speed manually to stop the chopper.. from rotating along with the rotors, and there's a key on the remote would be to slow down and speed up the motor from its equilibrium.
4. The input power in the receiver board would be 12v and current 8-10 ampere. It should be of range 500-800 meters. Sir can you please design such a RC circuit board along with the remote.
5. I am in search of such circuit board since last two years.
6. My project was stopped due to its absence. Sir please help me. For your convenience you can design two individual rc circuit boards one for main motor and tail motor and another for two forward and reverse rotating motors.
7. But the input current and potential difference in both circuits should be same, with same range that is 500-800 meters with its remotes or remote. Please also mention the name of the components required with numbering.

The Design

The requested circuit modules which are required for building the proposed RC helicopter are:

1) A 12V  PWM variable speed controller

2) A 3V motor reverse forward controller circuit.

3) a 9V motor regulator with a variable speed controller circuit.

All the above specifications needs to be controlled via a long range 433MHz RF remote control module.

The desired 433MHz RF remote module could be procured from any online store or from your nearest electronic dealer. The range of the remote control should be as per the required specifications of the RC helicopter range, here it's supposed to be within 1km.

For the discussed RC helicopter remote control circuit, a 6 channel RF remote module would be required, exactly similar to the one which was used for our earlier simplest drone remote control circuit.

The image of the same can be witnessed below:

The left side green board is the remote receiver module having the six control relays and this units needs to be installed inside the RC helicopter for the necessary control operations.

The right side unit is the transmitter handset which is supposed to be held by the user and the relevant buttons pressed for commanding the relay board with the corresponding motion control info.

Now lets see how the six relays needs to be configured with the various PWM circuits and installed inside the RC chopper, from the following details:

Remember the relay contacts shown in the receiver board are all blank by default, meaning their N/C and N/O contacts are not wired and must be wired as illustrated in the following diagrams.

According to the request, the 9V motor and the 12V motor speeds need to be controlled through the subsequent pressing of the remote handset. The circuits for implementing this function are shown below:

Motor Driver Schematic

Circuit Operation

As may be seen in the schematics, a couple of identical IC 555 PWM circuits are employed for the purpose. Four out of the six relays are engaged here with their relevant contacts wired across the shown connections.

In the design the IC 555 is rigged as a basic astable circuit, assigned to oscillate with some specified frequency depending upon its R1, R2, and C component values.

A voltage follower in the form of IC 741 is configured with the control pin#5 of the IC 555 in order to vary the PWM content at pin#3 of the IC 555 in accordance with the indicated relay operations.

The voltage at pin#3 of the IC 741 is followed or transferred at is pin#6 and subsequently to pin#5 of the IC 555. Depending upon pin#3 capacitor charge level this varying voltage could be anywhere between the supply voltage limit and zero.

The charge level on the capacitor is varied or changed by simply charging it or discharging via the relevant relay contact activation.  To charge the upper relay contact is closed or activated enabling an rising voltage at pin#5 of IC 555 whereas activating the lower relay contacts discharges the capacitor causing a proportionately lower voltage to appear at pin#5 of the IC 555.

The above actions translate the pin#3 results into a correspondingly varying PWMs which in turn causes the motor to either run faster or slower.

Fro the 9V motor a series of diodes can be seen attached at the emitter of the driver transistor, this ensures the required drop in voltage and helps to convert the 12V into an approximate 10V regulated supply as per the specifications of the motor.

3V Motor Reverse Forward Operation

The third and the last demand in the request is for the reverse/forward control of the 3V motor using the RF transmitter handset button press.

The remaining two relays can eb now used for this particular execution, and is done as demonstrated in the following diagram:

Here also we employ the versatile IC 555 wired as a precise PWM generator circuit. The PWM is set appropriately through the 5K preset before finalizing the installations such that the speed of the motor is perfectly adjusted for the required equilibrium of the helicopter.

The relays can be seen simply wired to enforce the required reverse, and forward or a clockwise or anticlockwise motion for the motor in response to the toggling of the paired relay contact, which together form a DPDT relay.

In order to prevent a short circuit, preferably the receiver module should be modified for these two relays such that pressing either of the buttons causes both the relays to activate together rather tan depending on two switches to be pressed in sync for the activation.

This toggling can be expected to flip the motor rotation in the opposite direction instantly allowing the user to execute the required directional changes in the RC helicopter machine.

This concludes the circuit and relay wiring instructions for the proposed RC helicopter remote control circuit, for further doubts please do not hesitate to express them through your comments.