EEVblog Electronics Community Forum

EEVblog => EEVblog Specific => Topic started by: EEVblog on May 02, 2019, 10:14:59 pm

Title: EEVblog #1208 - Circuit Analysis & Debugging
Post by: EEVblog on May 02, 2019, 10:14:59 pm

Fundamentals Friday
Dave answers a beginner forum question of why their 74HC390 based breadboard counter circuit does not work properly.
Let's get up to our armpits in datasheets and troubleshooting.
A two sentence forum response turned into a step-by-step 27min video investigation involving rise and fall times, setup and hold times, metatability, optocouplers, bypassing, open collectors, and connector traps for young players.



https://www.youtube.com/watch?v=x0Dk5SSCMZo (https://www.youtube.com/watch?v=x0Dk5SSCMZo)

Title: Re: EEVblog #1208 - Circuit Analysis & Debugging
Post by: Raj on May 03, 2019, 08:49:20 am

Quick googling resulted in 74HC4024-Q100, ripple counter with schmitt 'cp' input....7bit though

Title: Re: EEVblog #1208 - Circuit Analysis & Debugging
Post by: mancausoft on May 03, 2019, 09:06:00 am

About the noise of the audio, if you have it you should disable NFC before start shooting.
 I have the same problem and same type of noise, and it's seems was the NFC.

In some case you can see the NFC signal on monitor/tv:
https://youtu.be/Xf5-yam1wKc

I spent a lot of time to found the cause of this noise, because was present even on  airplane mode.