Stereo Circuits

Have you ever wanted to run a TV, stereo or other appliance while on the road or camping? Well, this inverter should solve that problem. It takes 12 VDC and steps it up to 120 VAC. The wattage depends on which tansistors you use for Q1 and Q2, as well as how "big" a transformer you use for T1. The inverter can be constructed to supply anywhere from 1 to 1000 (1 KW) watts...

DISTRIBUTION module is part of ATVRC repeater system. It was designed for driving of multiple transmitters (DVB and analog) plus other AV devices like: webcam, local monitors and links using main AV signal source. Module could also work standalone with own syncho detection. Moreover, it produces an simple PAL test pattern and test audio during repeater inactivity...

This is a simple Surround Processor with the degital delay method. This audio processor is not using any special function ICs that difficult to get parsonaly, and desined in only general purpose ICs. Of course the Digital Delay Block of A-D, D-A and delay logic is also using only general purpose ICs. This is the key feature that easy to build it. The type of this Surround Processor is generating the surround effect with processing two channels of stereo source. Most of those are generates the surround effect with separates reverberations from source signal and applies any processes, and then mix it to front channels or output as rear channel. Separated reverberations are applied to delay as sounds refrected in the hall. This is important process on the every surround processors. Delay time is tipicaly several ten miliseconds, and this time affects the tendency of the surround effect...

This surround-sound decoder is based on the "Hafler" principle, first discovered by David Hafler sometime in the early 1970s. The original idea was to connect a pair of speakers as shown in Figure 1, for use as the rear speakers in the surround setup. This is ok just as it stands, but problems are created if the main speakers are bi-amped or using bridging, for example, since there is no longer a full-range / full power signal available for the rear speakers. This circuit works by allowing the rear speakers to reproduce only the difference signal between the left and right outputs. All stereo encoded material has some difference between left and right channels (if it didn`t, it would be mono), and it is this difference signal that is reproduced by the rear speakers. It is important to ensure that the connection between the rear speaker negative terminals is not earthed, or they will simply be in parallel with the main speakers...

This circuit speaks for itself. When the phone line is okay, Q1 acts as a short with a very high ohms value via R1, R2, and R3 for a total of about 66 MegOhm so very high. When the phone line is cut (open), it activates the MosFet (Q3) via transistor Q2 to drive the load. Substitutes are fine, none of the components are critical. The `Red` and `Green` wires of a telephone wire are *NOT* the positive and negative. They are the TIP and RING wires. So, don`t get confused why the red telephone wire is connected to ground (Gnd). The `LOAD` can be anything you like. A relay, motor, lamp, tape-recorder, stereo, security system, or whatever. Keep in mind that Phone companies don`t like to have anything `directly` connected to their wires for obvious reasons, so use this circuit at your own risk...