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Noob: Adding DC offset to preamp output

Discussion in 'General Electronics Discussion' started by WaveyDavey, Jul 4, 2011.

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  1. WaveyDavey


    Jul 4, 2011
    I'm pretty much a newcomer to electronics, so be gentle, please.

    I need to create a preamp to boost a guitar signal for a microcontroller project I'm designing. I've found plenty of simple circuits that seem appropriate. But, as I understand it, preamp output varies about 0v, and all the circuits I see have a DC filter cap on output to block DC.

    Say the preamp produces an output -2V to +2V (around -0v centre point), and my microcontroller reads inputs 0-5V, how do I bias the preamp output by +2V to be 0v to 4V? Is it a simple as a potential divider around the output or am I being dim?
  2. Resqueline


    Jul 31, 2009
    Yes, that's the most likely-to-work universal solution (two equal resistors, 10-100k). It'll place the A/D at a 2.5V bias and allow a peak amplitude of 2.5V.
    If there's a lot of noise on the 5V however it may find its way into the A/D. If that becomes a problem then add a capacitor and an extra resistor.
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