Here you find schematics for a full-duplex party-line intercom.

FAQ: How do you build "Quad fork box?"  
Answer: Just connect COMM+ from all of your units, likewise COMM-.

I should write a new index.html but I'm too lazy.
Sorry for the inconvenience...

Kaoru "Mad Player" Maeda

• newschem.gif: The schematics. This version is good for an EC-microphone. Any cheapest "For multimedia PC" headsets will be OK.
• newmic.gif: Parts layout.
• newpat.gif: PCB patterns.
• newpat6.ps.gz: 6 patterns mag 0.80. PostScript gzip-compressed. Can someone make this into a PDF?
• index_oldver.html: Description for the older schematics. Please substitute patterns and schematics appropriately.

Here are some photos on the way building.

Spraying fluxes.
Mount jumpers, laying resistors first.
A complete unit.
Parts side close up.
Patterns side. Two white jumpers are for on-board Mic-Vols.

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