pic microcontroller discussion list wrote:
> I want to interface to a Hi-Fi type Amplified, which has a regular
> line level input. But I'm having great difficulty in finding out what
> exactly "line" meaans. There's a lot of conflicting information out
> there.

There are several 'standards', but if you assume it will be around 0.75Vrms
maximum, you'll be in the right region.

> Second question, derived from the first... Given an astable 555
> outputting about 1.3 KHz, close to 50% DC, and 0-5v Pk2Pk, how can I
> convert this to "line level" ?

I'd probably start with a series capacitor (0.1uF or so) then a 2K2 : 2K2
potential divider off that output.  Look at the resulting level (which will
no longer be a square wave, but should have no DC offset), and tweak to
suit.

Note that most amplifiers around will be AC coupled anyway, so a potential
divider on it's own should be OK.  However, connect it to the input of a
Crown D150 or the like, and watch your speakers burn :-)

Nigel
--
Nigel Orr, Design Engineer                 nigel@axoninstruments.co.uk
Axon Instruments Ltd., Wardes Road,Inverurie,Aberdeenshire,UK,AB51 3TT
               Tel:+44 1467 622332 Fax:+44 1467 625235
                   http://www.axoninstruments.co.uk

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