morpheous87 Posted August 23, 2012 Report Share Posted August 23, 2012 Hi, I want to make this VA meter project for my 0-30V power supply unit(also project from here). I have a few questions about the VA meter. http://electronics-lab.com/projects/test/007/index.html is the project.- The power suplly, can exceed the 30V limit, and to be aroun 31-32V for example. The maximum input voltage for the VA meter is 30V, can this be harmfull for the VA meter?- One of the VA meter's inputs gets positive power directlly after the bridge rectifier. On the schematic the limits are 14-35V. In order the power suplly transformer has 2x30V windings, after the rectifier I expect voltage value above the 35V maximum?- Can I use separate 5V power supply only for the VA meters( with common ground with the power supply)This is for the current moment :)+Best Regards! Quote Link to comment Share on other sites More sharing options...
redwire Posted October 13, 2012 Report Share Posted October 13, 2012 Hi morpheous87, with the right tweaking you can get the display to work with much higher voltages. I set mine up to work up to about 60 V. It's been many years since I worked with this but here are some of the issues:1. The voltage signal to the chip must be less than 5 volts so the voltage divider needs to be changed to ensure your max voltage signal to the chip does not exceed 5v. The project you referenced was designed for a max of 30v so the voltage divider was designed with that in mind. 2. because the sense voltage in 1 above will represent a different value than the original program you need to change the software code to display the correct voltage.3. Most 5 and 12 V regulators don't tolerate imput voltages higher than about 30V. I think I used a LM317HV regulator to get to 12 volts then used a standard regulator to go from 12 to 5v.I think sample code was posted several years ago on this forum. Quote Link to comment Share on other sites More sharing options...
hemiyat Posted October 14, 2012 Report Share Posted October 14, 2012 Yes, great, “used a LM317HV regulator to get to 12 volts then used a standard regulator to go from 12 to 5v.” Quote Link to comment Share on other sites More sharing options...
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