Electronics Projects, USB Port Relay Control with Atmel Atmega8 article
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6 relay control units can be made via the usb port usb drive computer program code and schema files are pcb circuit to regulate the supply 9-12 volt ac section there on the SPI and RS232 connections
In fact, with the computer relay to control a simple inexpensive circuit there, but (the PC and the Device Control) these circuits turned the computer port to question his instantaneous even in the relays pull leaves microcontroller used in the system prevent this problem can only be undertaken
USB Relay Control Project
The relays switch max. 250V AC and have a switching current of 8A (depending on the relay used). In addition, can also use 4 inputs, which are isolated by optocouplers, are queried and monitored. The AVR simulates a USB RS 232 interface and so you can relay card can be easily addressed without problems via a terminal program or other software. The USB driver in the AVR firmware comes from the company objective development 6 Channel USB relay card to switch from various appliances, lamps or motors by a computer program via the USB interfaceThis can then using a web application even over the Internet. About the SPI connector would even be possible to relay card with other relay cards to cascade. The relay switch max. 250V AC and have a switching current of 8A (depending on set relay). Also you can also 4 inputs, the optocoupler are separated, queried and monitored. The AVR simulates a USB interface RS 232 thus can relay this card without problems on a terminal program or other software to be easy.
Source: ulrichradig.de/ USB Relay Control schematic pcb Atmega8 source code files alternative link: usb-port-relay-control-with-atmel-atmega8.rar alternative link2