A few years ago, someone gave me a small wireless infra-red keyboard, part no. RC-KB2, designed to be used with a Kenwood audio system. As soon as I saw it, I wanted to discover it`s transmission format. Why Because I would then be able to build a small receiver which would allow me to use this keyboard on a PC with a PS/2 port. Two years later,
Click here to download the full size of the above Circuit.
I finally found (or took ) the time to do it. This page`s purpose is to document the project. Maybe someone else would like to use a keboard like this one with their PC In any case, the receiving part of the code could be rewritten for other keyboards or even regular infra-red remotes. When the keyboard emits infra-red, it is not continuously. In fact, it modulates the infra-reds at a frequency between 35 and 38 Khz. I did not measure the exact frequency, but I assume it is in the 35-38 khz range because an infra-red receiver salvaged from a VHS Vcr receives the signal correctly at a pretty good distance. After looking at the receiver`s output with a digital oscilloscope, I understood how the data was transmitted. As my infra-red receiver had an active low output, a low level in the following diagrams indicates that an infrared wave was present. Right after the attention signal, the keyboard sends the data bits. The time elapsed between active pulses (560us) varies depending on the bit value being transmitted (1 or 0). A long time (approx. 1640us) represents a 1 and a short time (approx. 560us) represents a 0. I compiled a list of the codes emitted by most keys on the keyboard. The [shift] keys cannot be paired with all keys. The [Room B] keys act as a kind of [shift] keys but they cannot be paired with the same keys. Unlabeled keys on the keyboard do not generate events. This keyboard was designed for a specific purpose....
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: