Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.


One question regarding to 7402 IC

One question regarding to 7402 IC

One question regarding to 7402 IC

I want to create a SR latch using 7402 IC. I would like to read the output (i.e. Q value) from the IC using an ADAM-6066 which has the following specs for digital input:

Wet contacts: Logic level 0: 0~3 VDC Logic level 1: 10~30 VDC

My question is:

1. Does the 7402 IC have open-collector output? The datasheet says nothing.

2. If the 7402 IC does not have a open-collector output then can I connect A SN7407N IC to the output of 7402 IC and pull up the voltage from the output of SN7407N IC to 10-30VDC?

I look forward to your suggestions.

RE: One question regarding to 7402 IC

1) Most certainly not!

2) Most certainly!

Do keep in mind that the 7407 will essentially invert the output since pulling down a pull-up going to the ADAM means the ADAM will see an input '0' when the NOR gate output is HIGH.

Keith Cress
kcress -

RE: One question regarding to 7402 IC

My zerosevens didn't invert back in the seventies. Has that been changed? Can't believe it has.

I also think that I would be careful with the 30 V. It is both Absolute Maximum and Maximum Recommended. A 30 V supply usually isn't stable enough to avoid excursions above 30 V. I wouldn't sleep well if I hadn't made sure I was at a stable 24 V, or so.

Gunnar Englund
Half full - Half empty? I don't mind. It's what in it that counts.

RE: One question regarding to 7402 IC

No, I agree oh 7s do not invert but an open collector essentially does.

Keith Cress
kcress -

RE: One question regarding to 7402 IC

The 7407 is an OC buffer:

The schematic shows the standard emitter input, followed by an emitter follower, followed by an RTL inversion, followed by the OC inversion, so 2 inversions total.

Since, the 7404 can be added to either the Q or Q_bar output, or both, you can do whatever is needed.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!
FAQ731-376: Forum Policies forum1529: Translation Assistance for Engineers

RE: One question regarding to 7402 IC

Is it even possible to buy a 7407 today? Just wondering.


Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close