Hi
Its a shame that the more easily available 555 chips don't
work well into the Megaherts. They are easy to get and a
pair of them would have made a reasonable separator.
I have a schematic for the separator used on my Polymorphic
computer. It uses another hard to get VCO chip. It uses
a MC4024, an external charge pump, 96L02 oneshot and
a few more TTLs.
Dwight
Date: Sun, 21 Sep 2008 23:38:07 -0700
From: eric at
brouhaha.com
To:
Subject: Re: Z80 home brew with FDC
Allison wrote:
It can also be done with a small amount of ttl.
An analog PLL data separator using a 74LS629 VCO or the like is fairly
easy to make, though you do have to be somewhat careful with the PCB
layout. IIRC, such a design is given in the 179x app note.
Building a good digital data separator out of TTL takes a fair number of
parts, which is why it was so rarely done. The DPLL design in the 179x
app note isn't very good.
Eric
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