Attitude Sensor Schematic Circuit Diagram
Light Barrier Position Sensor: First Version
In this circuit (Figure 1), a light barrier is utilized as a position sensor, available in two versions. The first version incorporates an LED (D1) serving as the light source and an LDR (R2) acting as the receiver. The LDR is a vital component of a CMOS oscillator, generating a digital signal (pulse waveform). The signal’s duty cycle and frequency are contingent upon the intensity of the incoming light. In the accompanying setup, the sensor is employed alongside a positioner. The light-dependent resistor is partially obscured by a pendulum, causing fluctuations in the duty cycle and frequency of the output signal based on the actuator’s position.
Light Barrier Position Sensor: Second Version
This circuit, offered in two versions, employs a light barrier as a position sensor. In the first version, illustrated in Figure 1, the light barrier comprises an LED (D1) for illumination and an LDR (R2) for detection. The LDR plays a crucial role within a CMOS oscillator, generating a digital signal (pulse waveform) with a duty cycle and frequency influenced by the impinging light’s intensity. The sensor is designed to work in conjunction with a positioner. Notably, the LDR’s visibility to light is altered by a pendulum, leading to variations in the output signal’s duty cycle and frequency in response to the actuator’s position.
Direct Detection of Light Falling on LDR
By excluding the LED and pendulum, the light falling directly onto the light-dependent resistor can be harnessed to precisely ascertain both frequency and duty cycle. The refined version, depicted in Figure 2, enhances the positioning mechanism. A notable departure from the first version is the incorporation of a slotted light barrier. In the image, this version showcases a distinctive feature: the utilization of a slotted light barrier. The swinging pendulum within the slot consists of two basic tinplate strips (which can be cut from a tin), fastened together with a cloth-covered elastic band. A small amount of solder, applied to the strips’ end, acts as the pendulum weight. Similar to the initial version, the light receiver (photodiode) in the slotted light barrier is partially obscured, contingent upon the position of the positioner.
Pulse Generator for Position Indication
The photodiode, in this arrangement, propels a pulse generator constructed from two CMOS Schmitt-trigger inverters. This generator yields highly variable duty cycle and frequency. A direct indication of the pendulum’s position can be derived from the pulse waveform by utilizing a low-pass RC network connected to the generator’s output. Suitable slotted light barriers, like the TCST 1018 and TCST 2000 from Conrad, can be employed. The concept for this positioner originated from addressing challenges in adjusting motor speeds of a multi-rotor helicopter to prevent tipping. This versatile sensor, simple to construct and adjust, responds dramatically to minute tilts, finding potential applications such as a tremor sensor.