AV Switch circuit


Posted on Feb 6, 2014

Before applying power, check for shorts on the board. This design runs from a FIVE volt supply, connecting it directly to a 12 volt supply will kill it for certain. The current drawn is very small, in the region of 70mA so connect a small 5V regulator in line with the supply if you intend to use a 12V power source. For the prototypes I used a stan


AV Switch circuit
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dard 7805 regulator on a 2cm square copper sheet and even after running for two days it was barely warm to touch. When you are happy that the current consumption is OK, measure the voltage between ground and each of the outputs, it should be less than 0. 5V. If all is well you can connect a monitor to the video and audio outputs then put the unit in "self-test" mode by pressing the "Chan A both" and "DTMF" function keys simultaneously. You should hear alternating high and low pitched beeps at about 1 second intervals. Next, connect some audio and video sources to the inputs, in self-test mode the inputs are selected in sequence so you should see and hear the sources being selected one after another. Channel A and B sequences are staggered so you can confirm their independent operation. To exit "self-test" mode you can either switch the power off and on again or press and hold the "Chan B both" and "Antenna select" keys together until a rapid beeping is heard. You can release the keys as soon as the beeps start and after a few seconds the unit will initialise itself to its newly powered up state. The design described here is for a compact, low-cost signal router that can feed any of eight audio inputs and eight video inputs to two pairs of outputs. It also includes a DTMF tone generator and an automatic antenna selector circuit. All the functions are controlled from a pair of keypads, the function keypad decides on which...




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