While doing some background reading about the Philips I2C bus I came across an application note written by Herman Schutte (of Philips Semiconductors Systems Laboratory in Eindhoven). Mr. Schutte described an elegant mechanism for interfacing sections of I2C-bus which are operating at different voltages through the use of MOSFETs and pull-up resist
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ors. I had also been looking at a number of options for interfacing a 5V LCD panel to a microcontroller system that I wanted to run at 3V and so decided to try applying this idea to the data and control lines in my circuit. Although I was building the circuit by hand I decided to use a surface mount package for the MOSFETs. As three-terminal devices they are relatively easy to solder as long as you can hang onto them. The image above on the right shows some of the 11 MOSFETs in use on the 0. 1" proto board. I used the Fairchild Semiconductor BSS138 (datasheet) N-channel enhancement mode MOSFET which is available in the standard SOT-23 package from folks like Digi-Key. Below on the right are wave forms for the circuit using three different values for the pull-up resistors: 100k, 10k and 4. 7k ohms. These values were picked from what I had close at hand. The circuit functions with any of them in fact. A basic drawing for the circuit I`m using is here. (or here for browsers without JavaScript. ) As the schematic shows, the circuit is remarkably simple and straight-forward. I have this circuit in-use with an ATMEL AT90S8515 (at 3. 6864Mhz) controlling a Seiko L203400J000 20x4 character LCD module. The 8515 is connected to a 3V supply while the LCD requires 5V. The control lines, RS, RW and E and the data lines D0-D7 are each level-shifted with the BSS138 MOSFETs. The level-shifting imposes no directionality on the bus so both...
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.....
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