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  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

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

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