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September 10th, 2009 4 comments

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August 31st, 2009 1 comment

August 31st, 2009 1 comment

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August 26th, 2009 Comments off

ZX Spectrum +3 (Issue 1) Sound Fix *updated*

August 22nd, 2009 2 comments

Sound fix diagram here. (pdf)

from Cristian Secară Homepage:

The first release (the +3) has a fatal hardware mistake: the 128K sound output is completely distorted.

  • Tech explanation: the analog output of the AY-3-8912 sound chip was intended to be amplified by a one stage common-emitter transistor. In practice, they have forgot to put a resistor to the transistor’s emitter. The result: the transistor works in switch-mode – the sound is converted from analog multi-level amplitude to digitized two-level amplitude, same as the old 48K sound system.

source: secarica.ro ay8912 Demos

August 22nd, 2009 Comments off

August 21st, 2009 2 comments

August 15th, 2009 2 comments

August 15th, 2009 1 comment

August 9th, 2009 4 comments

August 8th, 2009 2 comments

August 8th, 2009 9 comments

August 6th, 2009 1 comment
Categories: Gallery, Texas Instruments