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Convert a 5V GPIO output to 240V anyone?

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Aug 24, 2009
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gpio output

Any ideas? For the electrical power experts? We were thinking of hardwiring. Here is a little background information. It is for a basic speech recognition system:

The 5V control bus will control in parallel a group of 240V devices on a power board of 4-8 mains sockets. The group’s final design for the power conversion section suggested it would be easiest to be able to control the sockets of a power board by controlling the on/off states with a 5V line. Since no apparent packaged solution was found, it will be necessary to manipulate preexisting power boards and fit them with switching relays.

In terms of deciding what is needed to seek a solution, the following design guidelines have been set:
When the microcontroller line is at 0V state, the associating power socket will be turned off/on standby
Hence when the microcontroller line is at +5V state, the associating socket will be turned on/active
The relay must be able to withstand constant high voltage pressure applied from the 240V mains supply. A suitable relay must also be a relay that’s contacts do not rapidly where from switching. Our predictions dictate that this will not be a major problem as switching will occur only when a voice command is entered.
The maximum current is for Australian wall sockets is 10A, the possible overload has been considered but a software approach will not be used at this stage. Instead a 10A fuse will suffice for initial design but this will be a problem. Perhaps further down the track a current LED indicator could be included as well as software precautions
A considerable amount of noise will be generated within the device’s container. Most of this will be 50Hz noise. This may prove to be problematic as unwanted noise generated may effect communications or a 5V line.

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