Z80 home brew with FDC

Eric Smith eric at brouhaha.com
Tue Sep 23 16:28:37 CDT 2008


Dwight Elvey wrote:
 > 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.

Brad Parker wrote:
> I thought that since it was not pll based, that sort of data separator
> was subject to drift

If it's a typical design, the VCO and charge pump are used as part of a 
PLL.  The MC4024 (note - NOT a CD4000 series CMOS part!) or SN74LS629 
are the most common VCOs for "discrete" PLL data separator designs. 
Neither is particularly hard to find in small quantities.

Eric



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