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Is there an y special rules when using th 74 series in a circuit?

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crutschow

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Not sure what you mean by "special". How familiar are you with logic circuit design?
 

audioguru

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The original 74 series are very old. They need a regulated 5V supply and use a lot of current.
A valid high input is +2.0V or more and a valid low input is +0.8V or less.
An output high is +2.4V or more and a low output is +0.4V or less.
The input floats high and needs a max of 1.6mA to force it low.
One logic circuit output can drive 10 inputs because its max low current is 16mA.

74LSxxxx uses less current.
74HCxxxx uses a supply from 2.0V to 6.0V and uses much less current.
 

fredy

New Member
I don't know it's just that when i experiment with them on a bread board they don work the way they should :confused:
 

ericgibbs

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I don't know it's just that when i experiment with them on a bread board they don work the way they should :confused:
hi,
What +Vrail decoupling capacitors do you have on the breadboard.?
 
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