Handbook Sync Circuit

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Re: Handbook Sync Circuit

Postby Harry Dalek » Fri Aug 10, 2018 10:15 pm

FlyMario wrote:I am playing with DesignSpark PCB at the moment. I saw online that it would draw Hops. But sometimes it feels like these get overly complex. I guess it is about making the component to where you like it and then saving them to a user file. One day I would like to take my little Mill ( https://www.amazon.com/gp/product/B01GF ... UTF8&psc=1 ) to make a PCB. And maybe send out to have one made. Just to say I have done it.



I like dip Trace
http://getintopc.com/softwares/developm ... -download/
It seems ok lots of parts to choose from in fact most i have seen so far on any of these programs but again it have the over lapping wiring arrrrr :roll:


Right now I am prototyping on one of these ( https://www.amazon.com/gp/product/B0040 ... UTF8&psc=1 ) Yes it is way wasted space but whatever. It will do.


never a waste always learning ,i tend to recycle my boards parts unless its a keeper .

Wow looks like I am being paid by Amazon.

I bought some of these the other day ( https://www.jameco.com/z/MCP41010-I-P-M ... 41744.html ) they look fun. Probably won't use on this project.


Not really tried a digital pot i have looked into them due to the cost over a trimmer or panel pot i have not got any yet they do look useful but .

Do you test those big Volume control type of rotary pots by measuring the leg to the middle to find out if they are good? I tried to use one for the video signal and it seemed no good. I had to cross the video input directly into the coupling cap before I got a signal to go through the op amps.

Yes pretty much ,i would use a new pot ,old ones your lucky if they are still ok wear of use they are the first things to play up ...i always put in a trimmer for testing at least as you can replace it when you panel mount a pot .
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: Handbook Sync Circuit

Postby FlyMario » Sat Aug 11, 2018 6:57 am

Robonz wrote:Hi Fly

Its great to see you making progress. Just a couple of notes.

1) There is no decoupling capacitor across the supply of the chip/s (in your diagram). You can end up with random sync pulses without it. Each op amp should have something like a 0.1uf or 0.01uf capacitor directly across the chip.

2) The input signal should be in a coaxial cable. You can end up with random sync pulses with out it.

Also your 5V rail should have at least 47uf capacitor across it for noise suppression.

Good luck
Keith


Well, crap. I have never used a decoupling cap in the past even though I had seen lots of digital circuits having them. Nothing I made with my Z80's ... memory seemed to have an issue. I watched a video today https://youtu.be/UW_XFGGTh0I and now I understand what they do. Ok look... I never said I was good with electronics... I just like playing with them. Fantastic results. Must apply this. Thanks for pointing me in the right direction Keith. I will let you guys know what happens.
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Re: Handbook Sync Circuit

Postby Steve Anderson » Sat Aug 11, 2018 12:56 pm

A fairly good demo of the function of decoupling capacitors in that video, sometimes also called bypass capacitors. The residual ripple in the waveform is probably due to using a 'breadboard' and/or the 'scope grounding.

As a rule of thumb I put one 0.1uF (100nF) disc-ceramic capacitor across the supply lines for every four chips, placing them closest to the chips running at the highest frequencies. That's for logic circuits of the type generally found in connection with NBTV. Also throw in a moderate sized electrolytic (say 100uF) to mop up lower frequency junk, one per board is usually enough. The cost is nothing compared to the frustration that you will endure one day, you've been lucky so far...

The disc-ceramic capacitors look like the attached photo, they're also cheap, so buy bucket-loads.

Ground/earth/0V lines should be as fat as is sensible.

I generally don't show these capacitors on circuit diagrams as they're implied, but there's no harm in putting them on the circuit...perhaps I should in future.

Steve A.
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Re: Handbook Sync Circuit

Postby Steve Anderson » Sat Aug 11, 2018 5:03 pm

As an example I attach a photo of a board for the SSTV-625 up-converter at the start of the build. There are five 100nF/0.1uF disc-ceramic capacitors scattered around the board plus another on the underside. Note the one within the 40-pin socket for a processor which runs at 64MHz - this is essential. The smaller paired caps are pert of the crystal oscillator circuit for each processor (there are two processors on this board - hence the two six-pin programming headers).

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Re: Handbook Sync Circuit

Postby FlyMario » Sun Aug 12, 2018 3:17 am

See, that is your board and this is mine...

boardv3.jpg


I think this forum should adopt a policy that no one gets to post pictures of their board unless they look at least as scrambled as mine. You know, I have rebuilt things before just because I couldn't stand the way the board looks. hehe
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Re: Handbook Sync Circuit

Postby Harry Dalek » Sun Aug 12, 2018 8:07 pm

FlyMario wrote:See, that is your board and this is mine...

boardv3.jpg


I think this forum should adopt a policy that no one gets to post pictures of their board unless they look at least as scrambled as mine. You know, I have rebuilt things before just because I couldn't stand the way the board looks. hehe


Well it used to bother me to have a single wire on top of the board as i like to have every thing neatly wired under via copper wire but going more complex the wires in the old rats nest idea had to be used ,i still try keep things neat as i can but its more important it works than looks .
So if it works for you that's all that matters .
If we all here constructed the same thing i am sure the end results would all have their on construction style neat to messy but that is to the eye of the beholder :wink:
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: Handbook Sync Circuit

Postby Steve Anderson » Mon Aug 13, 2018 3:47 pm

Below is how the SSTV-625 converter looked at around 99% complete, not a complete mess, but not that tidy either. There's nothing on the underside except one 100nF decoupling capacitor where I ran out of room on the top-side.

The plan is for it to also do NBTV-625 (when? - good question!). There should be no hardware changes to this board, but I haven't even started on the software for the NBTV part.

Steve A.
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Re: Handbook Sync Circuit

Postby Harry Dalek » Mon Aug 13, 2018 6:37 pm

Steve Anderson wrote:Below is how the SSTV-625 converter looked at around 99% complete, not a complete mess, but not that tidy either. There's nothing on the underside except one 100nF decoupling capacitor where I ran out of room on the top-side.

The plan is for it to also do NBTV-625 (when? - good question!). There should be no hardware changes to this board, but I haven't even started on the software for the NBTV part.

Steve A.


Hi Steve
That's pretty neat to me very hard to make plastic coated wire look good :wink: think all you can do is cut them to length and match the others bit of colour matching to their use if use can ,i still think the least of it the better .
Well i am still interested in the SSTV NBTV 625 line converter when ever its ready to construct i know you have to be in the mood to start something like this so when you are i will be .
Have to explain the PIC part of it what you will use to program it and such that would be of interest ,as for me i tend to stay away from these things .
Sorry for going off topic here
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: Handbook Sync Circuit

Postby Steve Anderson » Mon Aug 13, 2018 8:24 pm

Not really off topic Harry as you observed the way the insulation does shrink back. I use offcuts of multi-pair cable, strip out the insides and use them on stuff like this. It's the problem with PVC covered cable not meant to be soldered but used in punch-down IDC applications. Used extensively in telephone and broadcast installations.

https://en.wikipedia.org/wiki/Krone_LSA-PLUS

Attached is a photo of a moderately small Krone frame during installation of an Audio Suite in Qatar some years ago.

Each block takes 10 pairs of multi-pair cable, this is then 'jumpered' across to either the source or destination required. The advantage is changes are quick and easy. If you want to change input 10 of an audio mixer to be VTR1 instead of Radio Mic 7 - all you do is pull out the old jumper and run a new one. But - and is a big but - you MUST keep the documentation updated - no excuses!

The cream coloured cable is analogue cable, the green digital (AES). The red blocks are earth blocks to bond the screen of the cable to earth. Why they're not green I don't know, and I have asked Knone this question without an answer... - maybe red plastic is cheaper than green?

Steve A.
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Re: Handbook Sync Circuit

Postby Harry Dalek » Tue Aug 14, 2018 5:11 pm

Funny Steve them using red as earth ! i find green wire the hardest colour to find as a scrap and red the easiest most abundant colour to find so yes may be red is easier cheaper to make or just needed most in electronics.
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: Handbook Sync Circuit

Postby FlyMario » Tue Aug 14, 2018 9:26 pm

What gauge wire do you use Steve? Most of my wire is 26 or 28 AWG. I notice on one of the pictures above it looks like you are using wire pulled out of a Cat5/Cat6 cable. Mainly because of the stripes.
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