DigiLite Lesssons to be Learnt from the Past Projects

[batcfm]

First I would like to thank those involved in DigiLite (and Poor man’s DATV) to give ATV a new direction and purpose. Having been a BATC member since the 70’s and from the 90’s had wanted to get back into active ATV construction again. But had little time or knew what direction to go as it is important to have a common specification to make sure all equipment is compatible.
Having bought the BATC components, I am currently buying the remaining DigiLite components. I planned to build the F1CJN Controller as it used the common HD44780 LCD, which I have one available and was able to down load all of the support material. Where as the G8BYI design didn’t specify the LCD in the BOM or on web page, but the interface is obviously not for the HD44780. Secondly I have always had some difficulty downloading items from the DigiLite site. On clicking the green arrow button for the latest G8BYI code (or clicking on the blue hex button), I just get a very quick flash of a new empty window, but no error message to help me identify where the issue lies (site, browser IE8, firewall, etc.). I don’t know if this is a problem for others as I have not seen any forum postings on this subject. I have waited until the latest web site updates completed to re-check in case the situation improved. But probelm still exists for me.

On looking at the F1CJN design I noticed on closer inspection of the overlay diagram, that all of the PCB diagrams appeared to have some shorted pads. Being shorted to either the ground plane or to other pads. I guess that if I am correct this might be due to the creation of the PDF file. It would be useful to know if anyone else has noted this or has attempted to build this PCB with the as published PCB board diagram?
Similarly, I had been looking at the COMTECH mods information in particular the video output amp circuit and PCB, reference RX010.709. It was clear that there was an inconsistency between the circuit, overlay and PCB track diagrams. Ignoring the typo in resistor ID for the device that is not required for a split power supply. On U3 Pin3 of circuit is a 20k resistor, on overlay this is a 680pf capacitor. On the circuit and overlay there are 3 x 75R resistors. However on the PCB track diagram there are no pads for the left most 75R, just a straight track that would short out the resistor if fitted. Also the actual 680pf capacitor (C12) is connected to L2 & L3. This connecting pad is actually shorted to the ground on the PCB track diagram. Not sure if anyone has built this circuit and corrected these apparent errors

My point I am trying to make is that whilst it is OK to publish ideas, notes, and sketches if marked as such. But for technical constructional articles it is very important to make sure the information is correct. For ATV to grow and survive articles should cater for all level of members and non-members. To get active members across the UK must be an aim so that at any location it is possible to make contacts over the air with others, otherwise it will continue as a few pockets of activity for a minority of knowledgeable members. Not all members have an electronics degree or technical background that allows them to spot and correct such errors. I can visualise seeing a lot of discarded projects due to not being able to getting them to work due to incorrect information. Although generally there are people around who would help out if asked, and we now have a successful forum and the internet.

But I see DigiLite as a good start for a bright ATV future but must not be allowed to be dogged by errors in any future projects. I know we are not in a commercial business and we are “amateurs” but a little professionalism will help everyone involved in ATV.
I remember during the 1970’s when Practical Electronics and Practical Wireless magazines were full of construction articles. As a kid the frustration of having limited success in getting projects built to work. Talking to other engineers decades later it was a common theme of non-working projects. Was it that we were young, quality of components due to lack of pocket money, construction techniques, or the design? It was clear some designs were built from items in the author’s junk box and sometimes difficult to source the same components.

If my comments offend anyone then I apologise but I felt this needed to be said and back in 2009/10 when there was a shortage of copy for CQ-TV. I did start to write an article on this subject covering lack of copy, past experience of ATV, and lessons to learn. But I came across by chance the Poor man’s DATV and then later by DigiLite and the void seemed to have been filled with a new project for anyone who wanted to join in with DATV could do so.

[g8ajn]

If I can answer a few of your points batcfm ( sorry I don't know your name as you did not give it). The details from F1CJN were as supplied and I have no other details. Please remember that not all of the articles have been published by CQTV yet, there is a detailed article giving constructional details of G8BYI add-on board the website is carrying only the minimum information until after the articles are published to help those wishing to proceed with the boards ahead of the publication. There is a huge lag from the writing of an article to getting it published, the DigiLite articles were written a year ago.
Any errors on my website are always corrected quickly when they are pointed out, but I repeat, when they are pointed out. The folk producing these designs are amateurs and therefore are liable to miss an error or two. Clearly not something that you might be liable to but then I imagine that you have not produced any project articles for the CQTV magazine for us to judge.
I have not had any questions from anyone regarding the link to the software on the website, perhaps you have an early version of Flash on your pc? With twenty or more add-on boards being sold by BATC shop I think we might have heard if there is a problem, and all boards have been built and checked by several local amateurs before the articles were written up to avoid any errors.
The DigiLite article is not connected with the Comtech article on my website yet you feel that because the add-on board pdf for the Comtech has errors in it that the DigiLite is also incorrect.
I have received no other comments despite my email address being available on the front page of the website you appear to have made no effort to contact me about your problems which could have been quickly resolved as they are so petty.
I will go over the various points you make and see if they are valid and I will make any necessary changes quickly and will report them on the first page of the DigiLite section. Please do not knock the efforts of the DigiLite team who have gone to great lengths to provide a cheap and effective entry to Digital ATV and the BATC who have backed this project from the outset and provide an excellent magazine for just £4 a year.
Dave G8AJN

[F1CJN_alain]

Hello
I have just verified that :
- I have send a zip package with all right and good files (included PCB Pdf file with not short circuits)to the BATC
- The pcb is not well reproduced on the Digilite site with many short circuits (due to a new digitalisation ?)
I joint the original pdf file as a zip file with this message.
Best regards
Alain
F1CJN

[g8ajn]

Thanks Alain. I have added the zip file to the website to replace the original which seems to have suffered in the compression somewhere.
Best wishes
Dave G8AJN

[M0ATV]

I planned to build the F1CJN Controller as it used the common HD44780 LCD, which I have one available and was able to down load all of the support material. Where as the G8BYI design didn’t specify the LCD in the BOM or on web page, but the interface is obviously not for the HD44780.

As I found out after building the bloody thing !

[F1CJN_alain]

Could you precise why the interface with the LCD44780 does not work ?
And the precises technical issues you have with this design.
This can ease the processe to help you.
It really works well as you can sse on the image on the Digilite site !
Best regards
Alain
F1CJN

[g4bbh]

Almost any of the commonly available HD4470 type displays work with the BYI circuit. I have tried 16x2, 20x2 and 20x4 displays here and all work. Just add a resistor for backlight if required and pot for display contrast. Unused LCD data bit inputs are grounded. The display contrast pot that I use is a 10K pot between 0 and 5V with wiper to display pin 3.

Dick G4BBH

[g8ajn]

From the forthcoming CQTV article on the G8BYI LCD controller addon board:
Connections for the blue/white 20 character display. The 100R is a LED current limiter (brightness) and can be changed to suit the users requirements.The 10k pot is the contrast control. I have uploaded a copy of the connections to http://www.g8ajn.tv/dlother3.html
These excellent 20 char white on blue displays can be found on Ebay.
Hope this is helpful.
Dave G8AJN

[g8byi]

To those who have issues with my Ultram controller, full tuning add on board.

The firmware IS written for the HD44780, that is what the Proton + Compiler utilizes, it knows nothing else for a Text type LCD.......Functions of pins will be the same only the pin numbers may differ between lcd manufacturers, so the datasheet for the panel should be checked.
I have had some builders who have had problems, but it always turns out to be the CLK and LE lines that had been reversed.
I have had no other emails from builders, except one requesting a detailed Build of Materials, this was supplied in generic terms rather than in detailed Farnell type part numbers, since builders may have parts to hand to build this simple circuit.
The main article for this design has not yet been published via the BATC CQ_TV magazine, but hopefully will appear soon. This was ghost written by David G8AJN, who graciously took on the task, from information supplied by myself.
So as to Lessons Learned from the Digilite Project - I say well done to everyone who has taken part, had a go at building and learned from the evolving experience.

Richard G8BYI

[batcfm]

I would like to thank the speedy response from Alain for the correction to the PCB layout and to Dave putting on the DigiLite site. As I said I thought it was in the pdf conversion as I have seen many strange and weird results at work with Supplier provide technical documents and circuit diagrams.

Going on to the download problems, I was asking to see if anyone else had a problem. As I do have the latest Flash software, and tried to access site by two different PCs. What I found strange besides getting no error message is that I can download other items on the same page. My next try was going to be at a friend’s using a LINUX box. I have investigated various settings but so far have drawn a blank.

On the latest DigiLite arrangement of pages:
OTHER ITEMS 2/5
- Clicking on top left green arrow there is a quick flash of a new window.
- Download of circuit is OK.
- Clicking on HEX FILE bottom left corner is OK.
3/6
- Clicking on V1.2 BOM is OK.
- Clicking on the Hex and Basic (blue background) creates a new window and then it closes.
4/5
- All of these downloads on this page have always worked OK.

I think there is a broken link on 1/5 as when I click on right arrow instead of page 2/5 an error page is shown.

As for my name I included it in the mandatory signature box. Which I didn’t realise was going to be printed right at the bottom of the posting rather than at the end of my text. It was there but just not where I expected. Sorry.

Thanks for help again.
Bill.