Gn0stik Posted March 14, 2006 Report Share Posted March 14, 2006 Ok, first post here. I'm a total newbie to electronics outside of replacing components that have obviously fried, some minor soldering etc, etc. I know nothing of what various components look like, and have very little understanding of what many of them do. Here's my story....I have a problem. My son who is still very young (10) got a kit for his homeschooling in which he can build a bunch of little projects on a bread board. He's never really taken an interest in science, but he's really biting into this. Perhaps it's his love for video games, but it's sinking in. Kinda cool really, but he's getting all these ideas for things he want's to build, or try to build, and I'm all for encouraging it, but I know squat, and can't help him with much of it.Anyway he's starting to become interested in free energy, hydro, wind, solar, etc. We've built little wind generators and taken them to the beach and powered a little radio we built from it (which fried but it was still cool). We've built little solar powered cars, nothing with hydro yet, but I imagine that will come up, I'm sure. When I ask him why he's so interested in this stuff, his reply is simply "No batteries, duh".At any rate, his latest interest is peizos, we went to a friend of mine's house and he was getting ready for a ski trip. He had these ski's with a piezo in them that lit a little LED, when you smacked them, or they were vibrated in any way. He though that was pretty cool as there were ("no batteries, duh") in them.So we did some research on piezos and learned a bit about EH/S (energy harvesting/scavenging). That flipped his wig. He had to play with some. So like true garage electronics buffs we started looking for devices that had piezos in them. We quickly abandoned lighters and ignitors as they require too much shock to generate a spark, albeit a large one, when they get the shock they need. We destroyed my wifes sonic toothbrush, and a few buzzers and speakers. All to no avail, and significant scowling, and scourging from the wife. So we turned our attention to the internet, and we finally settled on one from a supplier named digikey, who sells a product manufactured by Measurement Specialties inc. The data sheet says it generates 10 millivolts per microstrain, which he insured me was enough to illuminate an LED, which we will try first. Here's the URL of the data sheet. I got the 3rd one down from the top in the second table (page 4). http://rocky.digikey.com/WebLib/Measurement%20Specialties%20Inc/Web%20Data/Piezo%20Film%20Sensors.pdfMy son decided he'd like to smooth out the intermittent voltage of the piezo to the light so that when it vibrates light sort of "fades" on, and when it stops vibrating it likewise "fades" out, If you catch my drift.. .knowing that his is beyond my abilities, I argued that we only were hooking it up to an LED for testing and that we'd hook it up to other stuff later on once we knew it worked ok, so who cares if it blinks(dear god save me from this child). No dice, that's what he wants. I told him I though that that would be done with a capacitor or a inductor (not sure which), after hours of research on the internet. So now, we come to my question..... Drumroll..... Which one should we use, and types, and should I wire them in series or in parallel? *rimshot*feel free to edit my premature circuit drawing i've added below for your convenience. Quote Link to comment Share on other sites More sharing options...
Gn0stik Posted March 15, 2006 Author Report Share Posted March 15, 2006 Can't anyone tell me which way we should go with this? Or even if it's possible? BTW, if it's determined to be impossible, a small explanation would be great, as I will in turn have to explain it to my kid. I understand your hesitance, as it's quite possible that, helping a kid with this kind of interest at such a young age could mean your helping the inventor of the device which will destroy the world at some point in the future. But still, I would have thought, as active as this board is, we would have gotten at least one response. Little help here? Quote Link to comment Share on other sites More sharing options...
Staigen Posted March 15, 2006 Report Share Posted March 15, 2006 Hi Gn0stikWhat is it that you have bought from DigiKey? All i get in the link you providedis an old pricelist from 2001, and on page 4 there is no second table! ??? ??? ???No wonder you dont get any answer!Show us an accurate datasheet of what you bought, and i will look at it, but icant promise you what to do.//Staigen Quote Link to comment Share on other sites More sharing options...
audioguru Posted March 15, 2006 Report Share Posted March 15, 2006 IF the piezo is big enough and you hit it hard enough, the LED will blink. I don't think it is big enough to charge a big capacitor to continuously light an LED. Quote Link to comment Share on other sites More sharing options...
Gn0stik Posted March 15, 2006 Author Report Share Posted March 15, 2006 Hi Gn0stikWhat is it that you have bought from DigiKey? All i get in the link you providedis an old pricelist from 2001, and on page 4 there is no second table! ??? ??? ???No wonder you dont get any answer!Show us an accurate datasheet of what you bought, and i will look at it, but icant promise you what to do.//StaigenHere's one sheet that describes the general properties of most of their piezo film elements. It probably has WAY more information than you need but I believe it does have the info that you need. They might ask you to sign up, but I don't think you have to. On the sign up page it says you don't. http://www.meas-spec.com/myMeas/download/pdf/english/piezo/techman.pdfAnd here's a sheet that describes the power generation during a test they had wherein they physically shook a piezo (the one I bought coincidentally) by hand and recorded the outputs. http://www.meas-spec.com/myMeas/download/pdf/english/piezo/RB_GP_11.pdffrom this document is the following table:Frequency Quote Link to comment Share on other sites More sharing options...
Staigen Posted March 15, 2006 Report Share Posted March 15, 2006 Hi again Gn0stikIm not sure that this can produce enough current to light up a led,You have to try it, connect it to a rectifier bridge and connect thatone to the led, to see if the led lit, if it does, you can also connectan electrolytic cap too, to get the led to lit for a longer time.Do you have MSN or ICQ or something like that, its easier and fasterto communicate that way?//Staigen Quote Link to comment Share on other sites More sharing options...
audioguru Posted March 15, 2006 Report Share Posted March 15, 2006 The spec's mention an output current of only 2uA to 6uA for the piezo sensor. An LED uses an operating current that is 1000 times more. Quote Link to comment Share on other sites More sharing options...
Gn0stik Posted March 15, 2006 Author Report Share Posted March 15, 2006 The spec's mention an output current of only 2uA to 6uA for the piezo sensor. An LED uses an operating current that is 1000 times more.I don't see that. The only places I see where it give an output, is based on the strain applied to it in the form of millivolts per microstrain.And nowhere do I see an amperage value. the only other place I see it is in the hand shaking experiment paper. in which you see the results in the table of my previous post.still no amperage in that. where did you find it? Quote Link to comment Share on other sites More sharing options...
audioguru Posted March 16, 2006 Report Share Posted March 16, 2006 I don't see that. The only places I see where it give an output, is based on the strain applied to it in the form of millivolts per microstrain.And nowhere do I see an amperage value.The specs show an operating current of 2uA tp 6uA for their accellerometers, which is what I assume that you have.The specs show that the 1M ohm of the input of an oscilloscope loads-down the extremely high output impedance of a piezo sensor. High impedance means very low output current.Did you try lighting an LED with your sensor? Quote Link to comment Share on other sites More sharing options...
Gn0stik Posted March 17, 2006 Author Report Share Posted March 17, 2006 No they are sending me a sample with one pre-wired to it. They sent me the wrong parts turns out, so I called them up and bitched and they are sending me a free one. After telling them what I wanted to do they said they had samples with them pre-wired as demonstration units. They are the vibration sensors. Not the accelerometers. The accelerometers on their spec sheets are pressure activated ceramic sensors (for measuring g force). Technically they could measure shock, and vibration too, but they are not sensitive enough. The vibration sensors are thin film piezo fibers on a poly substrate. The one they are sending me is not by any means a super bright led, but it doesn't need to be. I can always scale up if I need that later (two or three piezos). I think my son will probably be bored with it once we finish however. What's interesting is that he said the led was wired directly to the piezo. No rectifier. Could I get a brighter LED to light up if I put a rectifier in there? Quote Link to comment Share on other sites More sharing options...
audioguru Posted March 17, 2006 Report Share Posted March 17, 2006 What's interesting is that he said the led was wired directly to the piezo. No rectifier. Could I get a brighter LED to light up if I put a rectifier in there?Certainly, if the rectifier has a transistor switch and a strong battery in it. ;D Quote Link to comment Share on other sites More sharing options...
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