This page describes the hardware and software design of a printer power switch controlled over USB from my Linksys NSLU2, aka Slug. The unit can, however, be controlled from any Linux box, and can switch anything, not just printers. My NSLU2 acts mostly as a file and print server. I can go for weeks without printing anything, so I want to keep th
Click here to download the full size of the above Circuit.
e printer switched off when I`m not using it (it takes about 4W while idle, which must be more than 99% of its total energy consumption). But it`s upstairs, and I don`t want to have to go up and down stairs once to switch it on and again to collect my printing. So I decided to get a power switch. There are plenty of power switches out there. Mostly these are expensive things intended for server rooms (see this example ) with RS232 or Ethernet interfaces; USB would be more appropriate for the Slug. One cheap USB switch is this one which has been interfaced to a Slug, but it only seems to be available with continental European sockets. So I decided to build my own. For USB control I decided to use the same USB module that I chose for SlugTerm, using the FT245BM USB-to-Parallel chip. I use just one of its 8 output bits to switch the mains power using a triac. Here`s a photo of my breadboard prototype: I needed to learn a bit about triacs before building the mains side of the circuit. There is more than you could ever need to know in this document from ON Semi. Here is what I learnt: Triac optocouplers come with various different sensitivities; the K3020P that Maplin sells is the least sensitive and takes 30mA. Futurlec sell more sensitive versions (the K3023P needs only 5mA) which could be driven directly from the USB chip. Choose R6 based on the optocoupler`s peak surge current: there will be a short time when it has turned...
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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