🚀 go-pugleaf

In article <1992Jul30.181542.19932@uwm.edu>, pegasus@csd4.csd.uwm.edu (David R Hucke) writes:
> Thank you all for helping me out with my 8051 question..
> 
> Several said that I would pulling too much current through the port
> pin and I should use a transistor as a buffer...
> 
> WOuld somebody tell me how to do that?  Do I use an NPN or PNP?
> What does the schematic look like? 
> 
> Could somebody explain to me in clear english the theory behind the 
> operation of the transistor being used as a buffer?
> 
> Thank you very much again...
> 
> 
> 
> -- 
> pegasus@csd4.csd.uwm.edu                David R. Hucke
>                                         UW-Milwaukee Film Major
> --
The trouble with the system here is we seem to have about a 4-5 day turna
around on news, so its hard to be involved in threads like this.

I have successfully used CD4049 and CD4050 CMOS buffers to drive LEDs directly
without any limiting resistors for many designs, just wire the LED from +5V to
the o/p of the buffer. This is the tidiest solution and its legit, its in
either an early National or RCA CMOS data book and does the calcs to show that
the chip doesn't exceed its rating and will self current limit, effectively
a hex LED buffer. Don't use for supplies greater than +5V tho! :)
-- 
Bruce Spedding
Materials Science and Performance
Industrial Research Ltd,     Fax: +64-4-569-0132
P.O.Box 31310,              Work: +64-4-569-0485
Lower Hutt,  ( NZST : +12 ) Home: +64-4-562-8522
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