Capacitive proximity sensing has been a very popular topic with our audience over the past year. For your convenience, at the end of this article, there is a hot-linked list of related articles published at Planet Analog. To read Part 1 of this article, click here. ) Now that we have discussed the theory about the sigma-delta modul
Click here to download the full size of the above Circuit.
ator, let us design a simple proximity sensor that will detect an approaching hand and switch on an LED. A 0. 5 mm2 wire, 10 cm long, is chosen as a sensor. Figure 7 shows the schematic of a proximity sensor circuit built using the CY8C21434 mixed-signal array from Cypress Semiconductor. The resolution of the sigma-delta modulator is set to 14. CINT and Rdis are the only external components required for the sigma-delta modulator. The count value from the sigma-delta modulator is passed through an IIR filter to form a reference count called Baseline. By selecting the filter response of the IIR filter, high-frequency noise on the instantaneous counts are rejected, but slow changes caused by temperature, humidity, and other factors are tracked. If the difference between the instantaneous count and the baseline exceeds a threshold, the firmware reports proximity. Figure 9 is the C code for the above flowchart. This is the most important stage of the development. Using the debug port and a PC GUI, display the Instantaneous counts, Baseline and Difference counts from the sensor. Perform the following steps: 5. The HYSTERISIS value in the firmware should be set in such a way that noise in the system does not create oscillations in the output. A few counts more than the noise level should work fine. We now have a proximity sensor. Watch the LED being turned ON and OFF as you bring your hand near and away from the sensor. Proximity...
This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of....
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is....
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to....
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This....
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the....
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,....
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the....
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power....
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....
characters left: