Comparison of ic 74c04 and 74c14

The pins of IC 74C04 and 74C14 are the same. Can either one take place instead of the other in the circuit like a transistor tester (in circuit). Both operate between 3 & 15v and max of 18v.

pgr2002 said:

The pins of IC 74C04 and 74C14 are the same. Can either one take place instead of the other in the circuit like a transistor tester (in circuit). Both operate between 3 & 15v and max of 18v.

Click to expand...

Its true they have similar specs, however the '14 is a schmitt input. Which means that the detection levels of Vil and Vih are well defined and specific. Using a 74C14 instead of 74C04 is usually OK, but other way around sometimes not.

Can't comment on your tester application without further info.

They are pin compatible and function compatible but not the same device. The 74x04 family are simple inverters while the 74x14 are Schmitt input inverters. For your application thay may be interchangeable.

The output of the 74x04 devices changes state at particular voltages, crossing the threshold between high and low input levels makes the output change.
On 74x14 devices there are two different thresholds, it needs a higher voltage to change the output one way then a lower voltage to change it back, in other words there is overlap between the input levels needed to change the output. It is usually used to clean up signals that have noise on them because the difference in thresholds prevents small disturbances in the input being recognized. Schmitt inverters are also sometimes used in oscillators where the threshold difference can be used to charge and discharge a capacitor cyclically.

Brian.

pgr2002 said:

The pins of IC 74C04 and 74C14 are the same. Can either one take place instead of the other in the circuit like a transistor tester (in circuit). Both operate between 3 & 15v and max of 18v.

Click to expand...

The difference between an ordinary inverter ('04) and a schmitt trigger inverter ('14) is that there is hysteresis on the input. Hysteresis avoides transient "chatter" when the input is slow or noisy.

In other respects they are the same, and you should look at the data sheet for the specific devices.

kripacharya said:

Its true they have similar specs, however the '14 is a schmitt input. Which means that the detection levels of Vil and Vih are well defined and specific. Using a 74C14 instead of 74C04 is usually OK, but other way around sometimes not.

Can't comment on your tester application without further info.

Click to expand...

image of the circuit has been attached for ready reference. please give your expert advice.

thanks

It is wired as an oscillator so as per my comment in post #3, you will have to use the 74C14 version.

Brian.

The oscillator is a phase shift type so it will work with "14" Schmitt Trigger invertors or with ordinary "04" inverters.
BUT the "04" does not have the high current output current of the "14" so use the "14".

pgr2002 said:

image of the circuit has been attached for ready reference. please give your expert advice.
thanks

Click to expand...

Since the signals go from right to left, we can presume the circuit was drawn by somebody whose first language is written from right to left

I was mistaken and saw the "14" as a high current output 74HC14. The 74C14 is ordinary low output current Cmos which might not work in that circuit when the supply is only 6V because the LEDs will load down the outputs then it might not oscillate. It will work if the oscillator outputs are buffered.