[sdiy] CMOS chip questions

[Scott Gravenhorst]

Tom Wiltshire <tom at electricdruid.net> wrote:
>
>On 19 Jul 2009, at 19:13, Scott Gravenhorst wrote:
>
>> "David G. Dixon" <dixon at interchange.ubc.ca> wrote:
>>>> Why Would one need any TTL interfacing? Just tell me what's  
>>>> missing on
>>>> CMOS replacements for TTL chips. It's probably 7404?
>>>
>>> Samppa's definitely got a point.  Mixing TTL and CMOS is kinda  
>>> like putting
>>> '74 Chevy Impala parts in your Acura TL.
>>
>> There are times when one needs more drive current than CMOS  
>> provides.  One way to deal
>> with that is parallel drivers, but another is bipolar TTL.  I guess  
>> it depends on
>> exactly how much current one needs.  I think, however, that for  
>> most synthesizer
>> designs, such currents are more rare than common.  Stepper motors?   
>> But who puts a
>> stepper motor in a synth?
>>
>> Maybe some exotic thing that uses electromechanical vibrating parts  
>> excited by a synth
>> circuit?  (reaching)
>>
>> -- ScottG (who waits to find out about stepper motors in synths)
>
>Funny that you mention it but...
>
>We were talking at SDIY UK about the perennial problem with  
>programmable synths - once you load a program from memory, the knob  
>positions don't tell you anything anymore.
>The suggestion was made that the absolute best way around this would  
>be to have motorized controls for the entire front panel, like some  
>top-end mixing desks of old.

Yeah, but then the builder would need to be independantly wealthy considering the
size of some SDIY stuff I've seen.  But heck, lack of time (because of the damnable
day job) is also a problem for SDIY and could be dealt with only by winning the
lottery.  Fool that I am (I know the math), I buy the occasional ticket - if it
weren't for bad luck, I wouldn't have any luck at all.  )c:

Many years ago, I got a contract to help a mechanical engineer automate a contact
lens making machine.  He asked me to demonstrate a microprocessor (MC6800)
controlled stepper motor.  I could vary the speed of it rather easily and the thing
would sing different pitches as it operated.  Not alot of pitch range, but it was
interesting.

-- ScottG
________________________________________________________________________
-- Scott Gravenhorst
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