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logic inverter question

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Eclipsed

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I'm in the process of an engine swap, and I need a reliable way of inverting the 5v cam sensor signal.I'd hate to be stranded somewhere because a few 20 cent parts failed.The posted schematic is what I've come up with, and my question is, is there anything any of you would add to help with the function or reliability of this circuit? maybe a 5.1v zener to protect the inputs? Perhaps a better circuit altogether? Thanks in advance
 

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williB

New Member
your going to construct that circuit , instead of using a standard TTL inverter ?
the way i see it , there is nothing wrong with relying on a standard TTL part to do what you want..i mean we all rely on the ignition IC/ uController everyday , to get us where we are going..
one question ,where is the 5 V coming from??
 

Eclipsed

New Member
what do you mean by "standard TTL inverter"? I only require 1 inverter, using an inverter IC(if that's what you are refering to) seems like a waste.It is easier for me to not have to deal(in this case) with a 14 pin DIP as well.


BTW 5v is coming from 78l05 type regulator
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Eclipsed said:
what do you mean by "standard TTL inverter"? I only require 1 inverter, using an inverter IC(if that's what you are refering to) seems like a waste.It is easier for me to not have to deal(in this case) with a 14 pin DIP as well.


BTW 5v is coming from 78l05 type regulator
Presumably you've copied that (particularly strange!) circuit from a TTL chip?. All you need is the right hand transistor and collector resistor, feed it's base from a resistor (4.7K would be fine) - so, input to 4.7K, 4.7K to base. That's all that's required.
 

Dean Huster

Well-Known Member
The one thing that using an inverter from a standard logic pack will give you is higher bandwidth if you happen to need that. Open-collector logic always has lower bandwidth and slower switching times than pulled logic.

Check out National Semiconductor. At one time, they were working with some SMT "put the gate where you physically need it" circuits where you might have an AND gate in a single 5-pin teensy package or an inverter in a single 4-pin package.

Dean
 
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