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With the amount of equipment in home entertainment centers today the need to be able to vary the gain of the audio or video signal is needed. I found this particular circuit helpful when used in conjunction with the Universal De scrambler and a Stabilizer circuit I built for making copies of video tapes. It not only allowed me the ability to fine tune the video strength it also helped me increase the recorded audio which typically becomes poor when making tape copies. Circuit operation is straight forward for amplifier circuits. The second channel for the audio amplifier is made up of the same components except the other half of IC1 is used. Pin 6 & 5 are inputs and 7 is the output. Audio/Video Distribution Amplifier Circuit Diagram

Video Switch for Intercom System Circuit Diagram. Nowadays a lot of intercom units are  equipped with video cameras so that you can  see as well as hear who is at the door. Unfortunately, the camera lens is perfectly placed  to serve as a sort of support point for people  during the conversation, with the result that  there’s hardly anything left see in the video  imagery.  One way to solve this problem is to install two cameras on the street side instead only  one, preferably some distance apart. If you  display the imagery from the two cameras  alternately, then at least half of the time you  will be able to see what is happening in front  of the door. Thanks to the video switch module described  here, which should be installed on the street  side not too far away from the two cameras,  you need only one monitor inside the house and you don’t need to install any additional video cables.   Circuit diagram :...

Description  With this circuit we can amplification selectively the high signal of picture frequencies [Video] with result bigger clarity than this. The circuit should be placed between a Video unit and the reception Scart or the plug Video input of television receiver. The designing is simple, it’s based in three only transistor. The first stage of Q1 function as isolator - adapter of input impedance. The second stage round the Q2 in common base connection which the gain is determined by the TR2. The TR1, R6 and C3 determine the frequency response. The third stage round the Q3 works as output buffer and 75-ohm line driver. The TR2 should be regulated in a place where the circuit output voltage, to be 1Vp-p, in 75 ohm load. The circuit functions with 12Volts - 50mA well stabilized.  Circuit diagram  Part List R1=82ohm R2=5.6Kohm R3-9-11=2.7Kohm R4=330ohm R5=220ohm R6=470ohm R7=270ohm R8=12Kohm R10=2.2Kohm R12=180ohm R13=68ohm C1-4-5=100uF 16V C2=2200uF 16V C3=470pF ceram...

Video Switch for Intercom System. Nowadays a lot of intercom units are  equipped with video cameras so that you can  see as well as hear who is at the door. Unfortunately, the camera lens is perfectly placed  to serve as a sort of support point for people  during the conversation, with the result that  there’s hardly anything left see in the video  imagery.  One way to solve this problem is to install two cameras on the street side instead only  one, preferably some distance apart. If you  display the imagery from the two cameras  alternately, then at least half of the time you  will be able to see what is happening in front  of the door. Thanks to the video switch module described  here, which should be installed on the street  side not too far away from the two cameras,  you need only one monitor inside the house and you don’t need to install any additional video cables.   Circuit diagram : Video Switch...