|
Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets. |
|
Thread Tools |
6th Oct 2011, 2:26 pm | #1 |
Dekatron
Join Date: Nov 2006
Location: London, UK.
Posts: 3,496
|
TTL level output - how to feed signal into noisy cct?
This is related to my current post about components...
I'm making a simple PWM with a low-frequency (220Hz) TTL level output. It'll provide a signal to a buffer and modulator on a board that is noisy - as has a high-powered pulse xformer running at around 30KHz. Okay to use ribbon cable to connect my output to the input of the board? Twisted pair? What's the best 'transmission line' for such a signal. I'm sure it's not critical at such a low frequency but interested to know what's ideal.
__________________
Al |
6th Oct 2011, 2:57 pm | #2 |
Dekatron
Join Date: Jan 2003
Location: Bradford on Avon, Wiltshire, UK.
Posts: 3,310
|
Re: TTL level output - how to feed signal into noisy cct?
Will these be 5 volt pulses at 220Hz? I wouldn't have thought there would be that much interference(particularly as you are going through a buffer)-that's the point of digital. Can you sheild the 30KHz in some way? And make sure they are both well de-coupled.
__________________
"Nothing is as dangerous as being too modern;one is apt to grow old fashioned quite suddenly." |
6th Oct 2011, 3:15 pm | #3 |
Dekatron
Join Date: Nov 2006
Location: London, UK.
Posts: 3,496
|
Re: TTL level output - how to feed signal into noisy cct?
Tim, yep, thanks for that.
Oh well, good to hear that it's not critical. I think some salvaged ribbon cable is my choice.
__________________
Al |
6th Oct 2011, 3:49 pm | #4 |
Retired Dormant Member
Join Date: Mar 2006
Location: Sheffield, South Yorkshire, UK.
Posts: 1,587
|
Re: TTL level output - how to feed signal into noisy cct?
If you are concerned about noise getting off the board into your external PWM why don't you opto isolate.
Mike |
6th Oct 2011, 5:24 pm | #5 |
Dekatron
Join Date: Nov 2006
Location: London, UK.
Posts: 3,496
|
Re: TTL level output - how to feed signal into noisy cct?
Mike, great idea! Thanks
__________________
Al |
7th Oct 2011, 8:53 pm | #6 |
Dekatron
Join Date: Jan 2003
Location: Bradford on Avon, Wiltshire, UK.
Posts: 3,310
|
Re: TTL level output - how to feed signal into noisy cct?
It is, I wish I had thought of it! Should be fine at 220Hz.
__________________
"Nothing is as dangerous as being too modern;one is apt to grow old fashioned quite suddenly." |