AT 4-Switch - The Practical Guide of Multicopters

AT 4-Switch

4-way

The AT 4-switch is a four way analog switch, controlled through a PWM signal from any RC receiver.

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AT 4-Switch

The AT 4-switch is a four way analog switch, controlled through a PWM signal from any RC receiver.

 

The device is powered at +5 Volts from the RC receiver through a single servo connector carrying Ground, Power, and PWM control signal.

 

You just need to assign an empty channel of your RC system to the switch, and this would allow the operation of the switch.

 

All the four switches are operated simultaneously.

 

It is supplied with a piece of clear heatshrink to be installed by the user, in order to protect the circuit and secure the connectors in place.

The switch behaviour is effectively identical to a mechanical 4-way switch:

 

-          It is bidirectional: it can be used to select between two signals to a single output, or to forward one signal to two different outputs.

 

-          It can handle up to 400mA on each of the four switches.

 

-          It can transmit signals up to 18MHz, which includes PPM, PWM, or audio signals.

 

Even if the AT 4-switch uses 3-pin servo connectors, it only switches the signal (upper) wire. The central wire (typically power) is not connected to the PCB, which means that no power is passed through the switches, and the devices connected to the switch inputs/outputs must be powered externally. All the ground pins are connected together. 

When receiving a PWM control signal with a pulse length shorter than 1600us, the led will be GREEN, and the A pins will be connected to the main input/output:

 

When receiving a PWM control signal with a pulse length longer than 1600us, the led will be RED, and the B pins will be connected to the main input/output:

The connections are as shown in the pictures, with ground wire in the lower pin and signal in the upper pin. The middle pins are unused, except for the control connector (PWM input) which is used to power the board.

The input/output #1 is duplicated, being both connectors wired in parallel. This allows in some applications to avoid the use of a Y servo cable, when we need to select between two sources (1A or 1B), and then connect the output to two different devices.

 

The AT 4-Switch is supplied with a piece of clear heatshrink, to be installed with all the connectors in place, in order to protect the board and to secure the servo connectors in place.

 

 

SPECIFICATIONS

 

Size: 33x23x11 mm

Weight:  7 grams

Power: +5V

Maximum current on each switch: 400 mA continuous, 600 mA peak

On resistance: 0.28 Ω typical, 0.41 Ω maximum

Bandwidth (@-3dB): 18 MHz

 

 

APPLICATION EXAMPLES

 

Using two independent RC systems

 

As an ultimate safety system, the AT 4-Switch allows the use of two totally independent, redundant, RC systems. Also, this allows an ultra-reliable master and slave setup, with the Pilot in Command capable of regaining the control just flipping the transmitter switch associated to the AT 4-Switch, ideal for training purposes, without the mess of traditional trainer systems, where the two transmitters must be connected through the cable, and share a single RC link.

 

The four switches are used as double input, single output, selecting which of the two RC receivers is used, and then using one of the switches to select the PPM signal to the Flight Controller from receiver 1 or receiver 2, another switch for the landing gear channel, and the other two switches for the camera gimbal controls.

 

 

 

You can even use two 4-Switch in parallel, in order to be able to switch between more than 4 signals. In the figure below, an example for controlling all the channels in an airplane: