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4 channel stereo audio switcher

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Junior Member level 1
Feb 2, 2013
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Louisiana, USA
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My project idea, sounds simple, I just need to build one. What do you guys think? I have a car stereo with an cassette drive that I'm looking to use it's input for. The basic idea is there, some mods to it will be needed in the final design. I need to be able to enable and disable the deck after all modes are cycled through or use a separate toggle for it.

  • 1 decade counter with 5th output tied to reset.
  • 8 transisters wired in sets of 2 with their base tied to a output of the counter, collector tied to a single rca jack, with the emitter going to the op amp or to the radio’s cassette drive input. One of the sets of transistors, the emitter would go to one channel and the other to the other channel.
  • Possible op amp to account for any signal loss.
  • 4 leds tied to the outputs of the counter for input selection.
  • A switch tied to a debouncer (monostable 555 timer) for the clock to toggle input selection.
  • The input could be from a set of mono rca jacks or 4 stereo 3.5mm jacks.
  • Optional function, have a 5th input for the cassette deck with some extra transistors to power the motor.

Input welcome.

Not sure what you're trying to do, but you may be better off replacing with a car stereo with a 'line input'. Otherwise, you'll suffer from poor dynamic range
that is not really suitable for interfacing to modern audio outputs from (say) ipods, etc. Cassette circuitry was not developed to be compatible with modern
audio devices.
Also, unless you're willing to design a complex circuit, relays will be the most effective way to switch audio. The decade counter method that you mention could be
used to switch the relays. Or, you could just use a rotary switch - far simpler.

Well, the reason I'm wanting to use transistors instead of relays is I don't want the mechanical feedback and I'd like to save money from using what I already have. Relays are also more bulky for the purpose. I will be powering the circuit from 5v. I don't want a rotary switch bor the simple fact that its too old school. :p My stereo doesn't have a line input so I'm just gonna use it's tape input. wiring in between the head in the board. the circuit could be modified for a line input later on if this doesn't sound good... also, I've been using one if those cassette adapters to plug in my pc. I kinda want to do away with that and expand it a bit.

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