1964 Antique MODEM Live Demo

[Dave McGuire]

On Jun 6, 2009, at 1:42 AM, Ethan Dicks wrote:
>>>> Is it possible that the DC-DC converter is playing up?
>>>
>>> The USB serial devices I've seen have been a 1-chip design -
>>> presumably USB, UART, and level converters all on one die, with a  
>>> few
>>> discretes for the DC-DC converter.  I don't remember seeing any
>>> separate Maxim devices in them.
>>
>> Ah... I thought I heard of a USB-TTL level async serial chip (i.e.  
>> you
>> need to feed the asynch side through a MAXnnn or similar) and assumed
>> that's what was used in these adapters. Probably not.
>
> I know there are "FTDI"-based USB seriual converters which would
> presumably also have either an external MAXnnn or a bunch of discretes
> for a charge-pump and level conversion, but I haven't dismantled any
> of those.

   The FTDI USB-interfaced UART that I've designed with, the FT232BM,  
does not have on-chip level conversion.  My design used a MAX232  
powered from the system power supply.  (the unit was not powered from  
USB)

             -Dave

-- 
Dave McGuire
Port Charlotte, FL