MP

Shamim, I do not think you will find one simpler than the design with diodes that RDL posted. Still, with this one you do not have very good accuracy. MP

Ooops! Sorry about that Shamim. I attached the wrong drawing when posting. Thanks to RDL2004, it looks like you have what you are looking for. It is still simpler than the one I meant to post. Best of luck with your project! MP

Shamim, Are you looking for something like this? (click on the picture to enlarge it.) MP

Wow...let's just gang up on the guy. ::) I think if he is happy with the power supply that he built, he doesn't owe anyone test results. Just a note to the community that he is satisfied with the project. Admin of this site also built the original and it did not cause such problems as burning up. I see 90 some pages of discussions based on theory suggestions. Where are the test results for all of these? Why does someone have to provide test results because he does not agree with another 's theory? Let's request the theory guy provide the test results on both designs since he has implemented the discussion of change. (In other words) You have made your opinion. Let it go. MP

You need to read up on how comparators work. Breadboard this chip and get out your calculator. Then this can be a learning experience for you. You will be surprised at how easy it is once you get into it. MP

Look at the schematic in the data sheet. R Hi and R Lo determine the end points. As you can see, the chip is based on a series of comparators. MP

Wow...has this gotten off course to the topic. In response to that ...not completing the part of the course which required a mentor is what I was referring to. The course is not complete. As your school would advise, the mentoring is an important part of the coursework to become an Engineer. This is recognized by Canada as a necessity. Otherwise it would not be required in order to register as an Engineer. Perhaps I could have simply stated to Walid that AG is not a registered R&D Engineer in Canada where he lives. My main point in posting was that AG stated the original author was not an R&D Engineer and he was. Rebutting that statement with comment that the author looks strange and posting his picture as such speaks of prejudice and bigotry such as I have seen in other posts from AG. Many of which I have deleted in hopes that no one would see them before hand. This is an International forum. No one on this community has a right to put down anyone else based on where they live, what they look like, their ethnic background, or religious beliefs, etc. We all live in this world and all of us here on this forum are members because we have a common interest. Let's keep the other garbage out of it. As a final note I would like to say that this is not supposed to be a discussion of anyone's aptitude or appearance, although it did turn into that direction with Walid's conversation about respect. Please continue discussing the importance of data sheets here. There are other places on this community where you can talk about anything that you so desire (provided it is in line with the rules of the forum). Please help keep the community organized in their categories. Thanks, MP

If your printer does not have the capability to print negative, you can export as an image, then use your image editor such as microsoft paint, etc to invert the colors. Make sure the scaling is correct in Eagle for the image file format. It is much better to use a positive photo etch if you can. The negative print will use up a lot of your black ink and you will need a good quality printer to keep from getting pin holes in the black print on the transparency if there are large places on the film. Someone might have a better solution. I do not use negative images, but thought of this solution which will get you there if there are no other solutions submitted. MP

Walid, Perhaps you have misunderstood the conversation. No one has been disrespectful to audioguru. However, you might not know that audioguru is not an R&D Engineer. In fact, he is not an Engineer. He mentioned in another forum that he did not complete his Engineering course. In regards to being disrespectful, I find it disrespectful to say someone looks unusual when discussing their knowledge or capabilities. It is an insulting statement. Ones appearance has nothing to do with ones Electronic knowledge or capability. MP

It is my understanding that the author of the project is an R&D Engineer. I have seen him elsewhere on the web. You are throwing out rumor and speculation instead of fact. (theory? ;D ) Are you claiming to be an R&D Engineer? You stated what R&D Engineers do, then you started talking about your selection. I was a little confused of the meaning behind that. MP

Since this topic is about the importance of data sheets, I will add a little to that. Data sheets are very important to get an image of what a product can do and where it has limitations. The data sheets will give you some test results as examples, but one should note these tests are not the full story. They are only an example to get you started. If you limit yourself to the specs of the tests performed for the data sheet, you will have a workable design. However, if you perform additional testing of the device, in most cases, you will find that there are many more capabilities. This is where the split between theorist, hobbyist and R&D Engineer becomes clear. Only designing to the specs written in a data sheet are correct, and it will work well. However, performing tests and designing to parameters not given or specified in a data sheet are also correct as long as the testing was performed correctly to insure it is not a one-time result. This can work both for you and against you. There are other things such as elevation, barometric pressure, relative humidity, solar radiation,etc that sometimes must be addressed even though the spec sheet does not give you specification regarding it. Designing only from a spec sheet, will give you a workable product, but certainly leaves one with limitations compared to a design that is tweaked on the bench. MP

Sorry, no can do. I have no intentions of redesigning the projects on this site. Don't waste my time. Besides, there are those who have built this project and report it to be working well. That has quite a bit of weight over your claims since you have not built it. MP

Thanks for the reply Omni. Others have also built the original with success. MP

You are reading too much into the data sheet and not taking the application into consideration. The clock in the inverter circuit works. You have beat this subject to death in another forum. MP

Did you build the original design or the one with the modified parts list? MP

You should post a link to the project when you ask a question. Otherwise it is difficult for others to see what you need help with. MP

This topic has been moved to Electronic Projects Design/Ideas. Posted in wrong forum. Note that I will start deleting posts that are posted in this forum that do not belong here. [iurl]http://www.electronics-lab.com/forum/index.php?topic=10974.0[/iurl]

This topic has been moved to Electronic Projects Design/Ideas. Projects Q/A if for discussion of projects that are located on this site. Please help keep the forum organized and post in the correct location. [iurl]http://www.electronics-lab.com/forum/index.php?topic=10978.0[/iurl]

This topic has been moved to Electronic Projects Design/Ideas. Posted in the wrong forum [iurl]http://www.electronics-lab.com/forum/index.php?topic=10979.0[/iurl]

This topic has been moved to Theory articles. Posted in the wrong place. [iurl]http://www.electronics-lab.com/forum/index.php?topic=10975.0[/iurl]

Kachew, Are you looking for the formula for the CD4047? It is 1/(4.4 * R * C). R is in ohms and C is in Farads. There is a lot of tolerance latitude since this is only a square wave inverter. Square wave inverters are not used in circuits that require frequency and voltage precision since the items that require it would be damaged or would not work well with square waves. MP

Once again, the only value of your posts are personal conflict. It is posts like these that make me understand why no one would mentor you so that you could become an Electronic Engineer. As I stated earlier, the values posted in the project by the original author, Ashad Mustufa, have been bench tested and work well in application. The values you have posted will also work well. There is no value produced from this argument. MP

The posted values on the project have been bench tested. When someone posts something like the above quote, they should perform some bench testing instead of making such statements from theory and application notes. For the low frequency clock of 50 hz, these values work fine. As the TI application notes indicate, the R only has to be larger than a few hundred ohms. 1K is certainly high enough for this application. The TI suggestion for a higher R value helps with stability of high clock rates. 50 Hz is not a high clock rate. BTW- I did not choose these values. I only corrected the decimal problems in the original schematic. The project reads," Corrected by MP".....Not "re-designed by MP". There are certainly a lot of improvements that can be made of this or any other project posted on this site. However, note that the basic function of this project is correct. It is a simple battery powered square wave inverter. If you don't use the right transformer, you will not have good results. Other members of this community have built this project and are using it to power AC devices with success. As I have mentioned many times, theory is where one begins in the design process, but it is not worth much without the follow up of bench tests. One cannot make a final conclusion from theory and simulation without putting forth the work of actual application on the bench. You can never get enough information from a basic data sheet or application note to forego the bench work. Electronics is a "Hands-On"application. MP

Subodhthok, You are correct. The schematic does not show the pin numbers and the text in the project is not clear in using the terms "Offset Null" to describe this connection. To understand more about what RV1 is doing, you can perform an Internet search for "op-amp and Offset Null". You will find some pretty descriptive pages. Hope that helps. MP

I don't know why you wouldn't have the minimum 3 to 5 volts on the data lines of your parallel port unless you either measured incorrectly or you have a problem with your port. Check to see if it operates your printer. The ULN chip is not needed for parallel connection to an SSR. It needs no more current or voltage than your printer, if it were attached. MP