warda Posted June 21, 2006 Report Share Posted June 21, 2006 GUd evening !!EM working on RAdar speedometer from the schematic of this site .the url is http://www.electronics-lab.com/projects/test/021/index.html .Unfortunately the 74 AS ics use in this project are not available in my city . i wana ask is der any replacemnt Ic of 74AS which ll work accurately?I ve discussed this matter with another person on this community n his views are "I don't think that project works. I have noticed that its photodiode is backwards. It doesn't have accurate oscillators and doesn't have any calibration for accuracy.The same author has another project using 74A ICs that also doesn't work."AudioguruNow is there any other schematic which can resolve the matter?plz help me out !!with reagrdswarda Quote Link to comment Share on other sites More sharing options...
gogo2520 Posted June 22, 2006 Report Share Posted June 22, 2006 Hello warda the 74AS ic's or pretty much obsolite. You might try the 74LS series ic's it runs at the same voltage. have fun gogo Quote Link to comment Share on other sites More sharing options...
audioguru Posted June 22, 2006 Report Share Posted June 22, 2006 74LS is much slower than 74AS. 74HC is also much slower. Quote Link to comment Share on other sites More sharing options...
warda Posted June 23, 2006 Author Report Share Posted June 23, 2006 yes de problem is that 74LS and 74 HC ahave greater delay which ll decrease speed.Do any one have any other schematic of digital speedometer? Quote Link to comment Share on other sites More sharing options...
MP Posted June 26, 2006 Report Share Posted June 26, 2006 The same author has another project using 74A ICs that also doesn't work."How do you know these projects do not work if you have not built them and rely on comments from someone else who has also not built them? Most projects have links to the author. Why not contact the author directly? mailto:[email protected]MP Quote Link to comment Share on other sites More sharing options...
audioguru Posted June 26, 2006 Report Share Posted June 26, 2006 How do you know these projects do not workBecause photodiodes don't work when they are backwards. Quote Link to comment Share on other sites More sharing options...
MP Posted June 26, 2006 Report Share Posted June 26, 2006 It is rare to see anyone go through the trouble of making a project and then posting it if it does not work to begin with. In most cases, I see simple things like component drawings backwards, a line in the drawing that gets connected to the wrong lead or is missing a connecting dot. These are all drawing semantics. Keeping in mind that the original project works, you can easily get past these small details. It also builds knowledge. For those who are in school, keep in mind that when you are working in the Industry, these are things you will see on a daily basis. Drawings are hurried, and since the Company does not hire just anybody off the street, it is recognized that you will have some technical knowledge to begin. It is all a part of everyday electronics troubleshooting. Got a drawing with a backwards part drawn into it? Turn it around and build the device. Look at all the Smart Kit drawings...perfect example of this. The kits work, but not always the way the schematics show them.Thus, I repeat: How do you know the project does not work when you have not built it? You only know that there is a problem in the schematic. From a manufacturing point of view, these are two completely different things.MP Quote Link to comment Share on other sites More sharing options...
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