74122 IC as a monostable multivibrator    

 

 

Matt
Can CD4098 replace CD74HCT221 for +12V operation? For gate generator?
Thank

 

==================

t can be, but I caution using a retriggerable monostable multivibrator.  I have many SN74HCT123A chips and found out the hard way what their limitation is.

 

==================

It can be, but I caution using a retriggerable monostable multivibrator.  I have many SN74HCT123A chips and found out the hard way what their limitation is.

The original VIC circuit has a 74122 IC as a monostable multivibrator, same as the 74123, to adjust the gate.

It would be helpful to know what the limitation is, and propose a better solution.

=====================================

The difference being retriggerable versus non-retriggerable.  The non-retriggerable variant I find to be more useful for deterministic pulse generation because it delays a predictable amount of time regardless of incoming trigger signals--only the first trigger matters.  Granted in a looped dual configuration like used here in this driver board, either method works fine since you are guaranteed to only get one trigger.  But in other applications, you may not have this guarantee, so the pulse width or pulse delay may get extended when the chip gets multiple triggers that fire before the time delay has expired.  When you see this on the scope for the first time, you'll question whether your duration time is working as you have set it.  The answer is yes, it is, but is now non-deterministic because you have multiple triggers.

Bottom line:

  • Retriggerable -- uses the last trigger seen; looks at every subsequent trigger as a restart until the cycle is able to complete.

  • Non-retriggerable -- uses the first trigger seen; ignores any triggers after this until the cycle completes.

Depends on what you want to do.  In my experience the non-retriggerable one-shot is more useful overall.v

 

=====================================

 

Matt
What is direct replacement for cd74hct221 from CD 4000 series , for 12V supply operation?
Thank Matt

About Us

Secure Supplies Media Group is

an international collective of Hot Rodders photographers, writers & drivers with a shared passion for promoting the world's most exciting

Hydrogen car culture stories.

Team Secure

Editor in Chief: Daniel Donatelli 
Senior Editor: Simone White
Editor at Large: Johny Case
Commercial Director: Willem Coetzee
Community Manager: Ryan
Butters
Technical Editor: Jason Nash
Concept Artist:  Samuel Hill
Senior Contributors:  Jacky Bright
Contributors:  Sally Smith, Joanne Livey, Bruce Smith.

Contact Us

We're always very interested to hear your own stories as well as to receive your feedback.

Please New Members first but if you don't find what you are looking for then you are welcome to contact us via email, thank you.

Secure Supplies  Social

 Facebook- @SecureSupplies

 Twitter      - @SecureSupplies

 Instagram - SecureSupplies

 Pinterest   - Secure.Supplies

Event Partners

Untitled.png

Automotive Partners

logo.jpg

Back to Main Site 

www.securesupplyusa.com

Merchandise Partners

Manufacturing  Partners

Manufacturing.png

Secure Supplies Energy Power Gas Magazine ™

All Rights Reserved Worldwide. Copyright © 2012 Secure Supplies Limited Daniel Donatelli © 2009 

TRADEMARKS BELONG TO THEIR RESPECTIVE OWNERS. ALL RIGHTS RESERVED

 No duplication is permitted of this site graphically or
conceptually unless requested and approved in writing.

TERMS OF SERVICE // PRIVACY & COOKIE POLICY // LEGAL NOTICES // ADVERTISING OPPORTUNITIES

Work with us Employment