audioguru Posted August 23, 2004 Report Share Posted August 23, 2004 Hi Guys,Nice new project. Lotsa ICs.This project is here:http://www.electronics-lab.com/projects/automotive/011/index.htmlAutomotive catagory? No wonder I couldn't find it.For those of you who build this project, I recommend adding a capacitor across the power supply, and replacing the 555 IC with the CMOS version.The small, rectangular 9V PP3 battery increases its internal resistance as it is running down, causing the supply voltage to change with changing load current.As the 555 oscillator's output is switching, the power supply has large current variations (spikes of up to 400mA!) which will cause the battery's voltage to fluctuate wildly and which may disrupt the logic ICs, especially when the battery is getting low. A CMOS version of the 555 is recommended to be used here, since it has a much lower current spike and draws less operating current.The logic ICs also create a power supply current spike, but it is only a few mA.A power supply capacitor reduces battery voltage variations by supplying current when the voltage attempts to drop. Therefore I recommend adding a power supply capacitor of at least 100uF, and since I have a lot of cheap and small 1000uF at 16V ones, then I always use them in my 9V battery projects. Quote Link to comment Share on other sites More sharing options...
MP Posted August 24, 2004 Report Share Posted August 24, 2004 ;D ;D The project text already says to use CMOS for all ICs. MP Quote Link to comment Share on other sites More sharing options...
audioguru Posted August 24, 2004 Author Report Share Posted August 24, 2004 MP,All ICs in the project's parts list have CMOS part numbers, except for the standard, high-current 555.Perhaps the author doesn't know that the standard 555 draws a high switching current and is not CMOS.8-pin DIP CMOS 555's are available at Digikey as follows:TLC555CP Texas InstrumentsLMC555CN National SemiconductorICM7555IPA Maxim (Intersil) Quote Link to comment Share on other sites More sharing options...
MP Posted August 25, 2004 Report Share Posted August 25, 2004 audioguru, the author of the project only mentions to use the 555 IC (no specific type stamping) and to use CMOS version for all chips. You are making a mountain out of nothing. Nowhere in his reference do I misunderstand him to mean anything but that. He does not give specific part numbers for the chips. Only 555, 4027, 4017, etc. All of my 555 types live in the same bin. I read the numbers on the chip to determine which type I have in my hand. I also refer to them all as 555s (which they are), so the article reads as nothing strange to me.But it is good that you mention it as others will also misunderstand him as you have. I agree that for some, he should have spelled out the exact part to use and for others exactly where to buy it. Perhaps even with a link to mapquest directions for some. ;DMP Quote Link to comment Share on other sites More sharing options...
audioguru Posted August 25, 2004 Author Report Share Posted August 25, 2004 Hello,I'm a newbee and I built this project and it doesn't work with a battery, but works OK with my regulated power supply. I used a 555 IC just like in its parts list.Could somebody help me pleez? Mapquest couldn't.Here come these queries! ;D Quote Link to comment Share on other sites More sharing options...
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