Anotherpower.com Forum
Renewable Energy Questions/Discussion => Automation, Controls, Inverters, MPPT, etc => Topic started by: Mixerman on April 19, 2012, 06:19:28 pm
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This is my first post! I am new to electronic's, I have a radio shack learning lab, only done a few things with that!
Would this project be a good one for my learning lab?
http://www.aaroncake.net/circuits/steth.asp
Most of the threds I have read are people wanting to detect heart beat!
What I have in mind is a little different I don't know if it can be done the way I want it to.
I want to detect the clicking of a fuel injector coil going off an on! I don't want to listen , just the LED blink is fine.
In the plans there shows a OPTION to add LEDS! Could I just build that and eliminate the head phone part of the plans?
I would also like to have a prob to reach into a running engine and touch hard to reach injectors for the sound pickup.
Any help with this?
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What I have in mind is a little different I don't know if it can be done the way I want it to.
I want to detect the clicking of a fuel injector coil going off an on! I don't want to listen , just the LED blink is fine.
Are you going to hear the sound of the injector over the sound of the engine?
I'd be thinking more of using an inductive pickup and putting that right by the injector coil and detecting that, probably much more immune to noise.
Downside is - if the injector COIL is working, but it's all gummed up inside and not actually operating, you wouldn't pick it up this way.
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Yes , it will work without the headphone output but I think it would help you to have headphones more than you would think.
A couple of things to consider about this circuit . . .
- It does not include a sensitivity adjustment and it's probably too sensitive for the volumes that you want to sense
- It looks like the LEDs will display the audio just as you would hear it, might be helpful to have some threshold adjustment so it would only light up on the volume peaks
- An electret mic is very sensitive and a bit fragile, might try a piezo element but watch out for some High Voltage output from them which will destroy the opamp
That's all I can think of now
Nice project idea
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What I have in mind is a little different I don't know if it can be done the way I want it to.
I want to detect the clicking of a fuel injector coil going off an on! I don't want to listen , just the LED blink is fine.
Are you going to hear the sound of the injector over the sound of the engine?
Yes!
I have a harbor freight Stethoscope now! No problem hearing the injector click over the engine noise, its much louder! I just dont like wearing the thing around moving parts or 100K volts!
As for the frequency of the click sound compared to a heart beat I have no idea!
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Yes , it will work without the headphone output but I think it would help you to have headphones more than you would think.
A couple of things to consider about this circuit . . .
- It does not include a sensitivity adjustment and it's probably too sensitive for the volumes that you want to sense
- It looks like the LEDs will display the audio just as you would hear it, might be helpful to have some threshold adjustment so it would only light up on the volume peaks
- An electret mic is very sensitive and a bit fragile, might try a piezo element but watch out for some High Voltage output from them which will destroy the opamp
That's all I can think of now
Nice project idea
I've reading about the Piezo ele devices! I had no idea! there everywhere!
http://www.mide.com/pdfs/vibration_harvesting_conference_2008.pdf
I butchered a buzzer out of a PC mother board last night! I'll have to look more in the junk pile!
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Having issues with the inputs on the second op-amp in that circuit...
Why is there a cap (C3) in the positive feedback path if the goal is to filter the highs out (C4)?
Steve
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I'M really not tied to this set of plans! But its the only one I could find that included LED's, it took me 2 days to find it. I seen alot of different plans for such things as LEDS dancing with music, that sort a thing! I would like to keep this a small device. Won't be doing any dancing!!!!
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If you use a piezo. Put at least a 1000 ohm resister in series with it to control the voltage.
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I did some expermenting tonight! I hooked my meter up the buzzer and stuck a nail in the hold for sound to come out, then placed the nail into my running drill. The output was AC,about 6.0MV was all I could get.
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Sound is a very small voltage in the beginning
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Did a little more today
From the circuit descritpion:
• U1b operates as a low-noise Sallen and Key, Butterworth low-pass-filter with a cutoff frequency of about 103Hz. R7 and R8 provide a gain of about 1.6 and allow the use of equal values for C3 and C4 but still producing a sharp Butterworth response. The rolloff rate is 12dB/octave. C3 and C4 can be reduced to 4.7nF to increase the cutoff frequency to 1KHz to hear respiratory or mechanical (automobile engine) sounds.
I have a sepehoscope from harbor freight I can just place it on the running injector and hear it "snap" on problem!
I dont like wearing it around moving parts and 100K volts!!
Some of these injectors are hard to get to! Infact some engine dis-assembly is required to get to them, and thats just to check them for mechanical movement. Doing this with a prob using sound or light short-cuts this whole process, for the shade tree DIY'er!
I did some experment today with a (portable phone) earphone,I hooked the ear phone to my meter and a red LED , when I tapped the earphone the LED blinked dimmly and got a reading of about 29.0 MV, AC, used a min-max meter. Tap was more like a slap!
Thanks for your thoughts!
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Any small amplifier can power an LED directly, and the volume control will adjust the brightness.
Try searching for Infrared Audio Transmitter, build that but use visible LEDs instead of Infrared LEDs.
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I searched for it and found it! Its got a transmitter and reciever it ! Maybe its not the one you mean!
I have some plans that came with the RS learning lab, one of the plans is to "Build a super sentive op amp audio amplifier ( to listen to ants), this one also uses a speaker though!
Thanks
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You don't need the receiver. Just the transmitter.
The opamp will not need to be sensitive. Just substitute LEDs for the speaker.
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I put together most of the project today! Afew more options to add! If intrested its on page 74,75.76.
http://www.radioshack.com/graphics/uc/rsk/Support/ProductManuals/2800027_P1_PM_EN.pdf
For my bench test I placed the piezo pickup face down on the table, about a foot away I ran the portable drill resting on the table (eng noise mockup), about 2 foot from that I placed a 12v relay from a car on the table, (injector noise mockup)!
The projects responce to this was when the drill was running the LED was lit (maybe mid-way) I adjusted the pots until the LED were very dim, then tripped the relay, LED lit with the tripping of the relay! (maybe midway). So far its working!!!!!
Still have to try it on the real thing! Need to do some expermenting with a probe to attached to the piezo.
Still need to do the upgrade on the LED on page 76!
Spent most of the time trying to figure out the colors on resisters.
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Spent most of the time trying to figure out the colors on resisters.
RossBot could have helped you!
It will do both, conversion from the colours to the value, and from a value to the colours.
<RossW> !resistor 4k7
<RossBot> 3-band: yellow violet red gold. (unspecified, assumed 5%)
<RossBot> 4-band: yellow violet black brown brown. (unspecified, assumed 1%)
<RossW> !resistor orange white brown gold
<RossBot> 4 bands, 390.000 Ohms 5.00%
<RossW> !resistor brown black black red brown
<RossBot> 5 bands, 10.000 Kilohms 1.00%
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You could probably reduce the feedback resister (R3) considerably if it seems a bit touchy to adjust.
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Spent most of the time trying to figure out the colors on resisters.
RossBot could have helped you!
It will do both, conversion from the colours to the value, and from a value to the colours.
<RossW> !resistor 4k7
<RossBot> 3-band: yellow violet red gold. (unspecified, assumed 5%)
<RossBot> 4-band: yellow violet black brown brown. (unspecified, assumed 1%)
<RossW> !resistor orange white brown gold
<RossBot> 4 bands, 390.000 Ohms 5.00%
<RossW> !resistor brown black black red brown
<RossBot> 5 bands, 10.000 Kilohms 1.00%
Do you have a link to this? Cant find it.
Thanks
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Do you have a link to this? Cant find it.
Thanks
RossBot is available as commands on our AnotherPower IRC Chat channal
irc.anotherpower.com #otherpower (http://irc.anotherpower.com #otherpower)
you can click the link on the Top Right-hand corner of any page
Here are the commands that are available there
http://home.albury.net.au/~rossw/irc-converter-help.html
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You could probably reduce the feedback resister (R3) considerably if it seems a bit touchy to adjust.
OK, I'll give that a try, just have to move the wire and try it!
Now I understand, thanks for the link!!!
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Spent most of the time trying to figure out the colors on resisters.
RossBot could have helped you!
It will do both, conversion from the colours to the value, and from a value to the colours.
...
<RossW> !resistor brown black black red brown
<RossBot> 5 bands, 10.000 Kilohms 1.00%
Wow, wish I'd have known about that... I have the 3 + tolerance colors down, but the 4 and 5 band precision resistors irritate the crap out of me! :o
I really gotta play with more of the features on that thing! Can it solve world hunger? LOL
Steve
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We went out and tryed it on the wifes car today! It worked!!! I could hear and see the LED light flashing as the injector fired. The LED was not very bright though. I still have the upgrade to do though.
In the video you will see me connect a brass brazing rod to the Piezo pickup. then I will turn it over a try the other side, then back again. Listen close you will hear the injector working.
http://www.flickr.com/photos/18130316@N07/7103516039/in/photostream
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You can get one of those insane bright red LEDs from RS that will help with that... They'll blind you if just flat out powered with DC, but for quick flashes, the extra brightness makes 'em show up nicely in sunlight.
Steve
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Steve, I went down to the local RS and picked two Leds ( 276-0015) Package says Ultra High Brightness 10MM Red !! Intensity: 400mcd, FW current: 20mA, FW supply: 2.4V (max).
I just swapped them out with what I had, didnt work to well. Am I missing something?
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Shouldn't be any issue with it working with the circuit; at that level, an LED is an LED. If it's predecessor worked, this one should. But, when I went and looked up the part number, one of the reviewers said something about the polarity being reversed as opposed to what was listed on the package.
With what you're doing with it, it won't hurt it to flip it around; it will either light up or it won't.
If it still doesn't, you can test the polarity/functionality any number of ways, my personal favorite is just using a CR2032 battery (the type used for CMOS backup in computers) as a power source. A 9V with a 1K resistor works well for tests in a pinch as well. If you use anything besides a lithium coin cell to test, be sure to use a resistor - it doesn't take much to smoke an LED. You don't need a resistor to test with a coin cell because they can't deliver enough current to pop it.
Another way to determine LED polarity that I typically use is usually the "dish" of the LED is negative (where the die sits). This is true most of the time; there are odd exceptions with specialty LEDs (self-blinkers, etc).
Steve
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I flipped it around and it dosent work! Maybe its just me, when I look directly straight down both LEDS are much brighter. I might be expecting to much!
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Steve, I went down to the local RS and picked two Leds ( 276-0015) Package says Ultra High Brightness 10MM Red !! Intensity: 400mcd, FW current: 20mA, FW supply: 2.4V (max).
I just swapped them out with what I had, didnt work to well. Am I missing something?
I'd say at a guess you're missing about 15 years of technology advances.
In this day and age, nobody would call 400 mcd "ultra high brightness".
Here's a random RED LED specs I just found:
Luminous Intensity : 12,000 mcd
Emitted Colour : Red
Size: Ø5mm
Lens Color : Water Clear
Life Rating : 100,000Hours
Forward Voltage (V) : 1.9-2.1
Forward Current (mA):<= 30
View Angle: About 45-55 degree.
And $5/100 including shipping doesn't make them anything special!
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I'm not sure exactly what you mean by that... but yes, due to the shape of the package, it forms a tight beam.
One way around that is sandpaper to "cloud up" the lens.
It sounds like they are working, but I can't discern whether there is an issue electronically or not. Looking back on the schematic, it's calling for a bipolar supply (+/- 9V in relation to ground), so polarity of the LED is likely to matter very little. I hadn't spotted that before... :-\
The pulses you're going to get at the LED from an injector are going to be rather short, and so will appear fairly dim simply because your eye can't react as fast as the LED. There are a few tricks for this, but none that are in the "super simple" category.
Did you get rid of the low pass filter that was in the original schematic? Since you're not measuring things that only require low frequency response (like heart beats), this is probably working against you. I'd ditch C4 just as a test to see if this has any effect on the LED's output. Of course, you're going to have to adjust the levels and all of that once the cap is gone; the response of the circuit is going to be much different.
Steve
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The packaging says 16 degrees viewing angle, I'll try sanding one!
This is the plans free on line! I used these plans because it uses all the parts that come with the kit.
Yes! the sanding helped!!!!!!!!!!!!!!!
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Ok, this looks a little more like what you need. The supply here however is single ended, so polarity of the LED will come into play.
You have a full audio range (and then some) amp here, with all the basics to get you the output you're looking for.
The half of the op amp that's driving the LED has a fixed gain of about 30, and the preamp is set up with a gain of anything from unity to approaching infinity (not actually possible, but high enough to get the LED to light up, for sure!). In a nutshell, yes this thing is very sensitive if you need it to be.
You may find that you probably don't even need the 386 at all, since it's primary purpose is to drive the speaker. U1b simply taps off of the output of the 386 as it's input. While it may be providing the extra gain that the LED could need to see useful flashes of light, it's probably not necessary, and U1b (as drawn in the top schematic) can probably be connected to the "volume" pot's wiper directly instead.
If this isn't clear, let me know, I'll see about scribbling up a quick schematic.
Steve
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If you can draw it Ill try it!
My only experence in electronics is Glen's controler!
I supose the reason we would do this is to make the LED Brighter?
Thanks for your time!
Denny
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Well, since you're not interested in audible output, there's little point in having the 386 in there. Just extra parts that may or may not do much in terms of the LED.
Just as in the last diagrams you posted, the earphone/peizo/whatever acts like a microphone. The first opamp takes this tiny signal and gets it where the second opamp can generate an output that swings rail to rail. In effect you have an amplifier that has so much gain that it isn't really practical to use for reproducing audio, but is perfect for picking up on the tiniest vibration and alerting you by flickering an LED.
As I mentioned before, the flashes may be too quick for your eyes to perceive them as full brightness. To test for this, take the "probe" and rub it on something like a piece of cardboard that will give it some noise at the input. While you're actually dragging across the cardboard, there should be almost solid light coming from the LED.
If it's working properly, but isn't perceived to be bright enough from the pulses from the injector, then you need what's called a "Schmitt trigger" and a couple of other components to make the pulses at the LED "stick around" so that the light is more perceptible.
Steve
EDIT - Don't forget to adjust the gain pot (1M, R3) and "volume" pot (10K, R4) to get the output set right. If you're inside around a bunch of electronic equipment, there's a quick and dirty method for obtaining a "test" signal for something like this - your fingertip. Disconnect the peizo element, and touch the connection going to pin 2 of the opamp with your finger. It should cause the LED to light up full brightness.
[attach=1]
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Using op amps like that is producing AC on the output
you could double the output by putting 2 LEDs parallel but revers one of the LEDs so that light is produced on both halfs if the cycle
or run the output through a bridge rectifier before a single LED would make it brighter too
A piezo is capable of producing 1000 volts when struck sharply, I suggest a 1000 ohm resister between the piezo and the op amp
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I haven't done any thing yet! This it Wolf?
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gun mockup:
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Using op amps like that is producing AC on the output
you could double the output by putting 2 LEDs parallel but revers one of the LEDs so that light is produced on both halfs if the cycle
or run the output through a bridge rectifier before a single LED would make it brighter too
Actually, since it's a single ended supply, and no coupling cap at the output before the LED, the LED only sees strictly fluctuating DC, so one of the two LED's will never light up because it will always be reverse biased.
The bipolar LED or bridge idea would work with the split supply version earlier in the thread, however, and in fact actually is drawn as such.
As far as a peizo generating 1000V, while this is entirely true, it only really applies to a specially designed type of peizo crystal assembly. A buzzer element would shatter with the force it would take to get that spike.
But, even with that being said, if it were to ever see 1000V from a peizo at the input, a 1K resistor would represent little more than a short, dropping next to nothing from it (the op-amp's input impedance is MUCH higher than 1K, so there would be little if any drop across the resistor).
If you're worried about it, a 1K might be prudent in parallel (ie from pin 2 of the op-amp to ground).
EDIT - On second glance, it a resistor there will probably do more harm than good, as it will have a significant effect on the feedback provided by the gain pot. I'd just leave it out.
Steve
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EDIT - On second glance, it a resistor there will probably do more harm than good, as it will have a significant effect on the feedback provided by the gain pot. I'd just leave it out.
If you're that concerned about it, either a zener to clamp the input, or two 1N914/1N4148 etc, from opamp input to Vcc and Gnd will clamp any spikes that might happen, to the supply rail.
Reality is as you say - highly unlikely you will get even a few volts, much less a thousand.
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It strikes me that this is just amplitude modulating a led. This means noise will still light the led, and there is no real "squelch" control.
What if you were to just use the first op amp as a normal amp, and drove a second one with the inverted input tied to a reference voltage.
Feed the signal from the output of the first amp to the non-inverting input of the second op amp, and you will have a level filter.
It will produce square wave pulses, but only if they are above the "noise" threshold of the reference voltage (variable if need be, or just control the output of the first amp)
This allows you to screen all the noise out below the pulses you are looking for, and stop the led lighting on dull for low level noise, bright for the signal you want....... it will be bright for your signal (as that is a steady amplitude once you find it), and won't respond to any signal less than that reference and gain composite......
The wanted signal will then be obvious, as it's pulse will be full rail, and the noise will be zero....... the pulse will be all ....or .....nothing.... no in between.
Just another idea to consider before the build.
..................oztules
ok I'll shut up now... more complications you didn't want to hear perhaps, but I think it's worth some thought.
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You make a very good point Oz, and yes, there are several improvements I can think of on the design as well.
However in the interest of simplicity, I haven't added anything mainly because I believe the basic design is being worked out on an electronics experiment kit which has limited part count. While it wouldn't take much more than what appears to be available to make the threshold trigger, I held off making much mention since there are so many unknowns.
Steve
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Yes Steve, The circuit is on a " Radio Shack Learning Lab" The Fire ant mo niter is one the projects included in the kit, in the project book! It is also on line for free!
The assembled project responds (blinks) when the injector makes noise, I could see it and hear it! (speaker)
It sorta adjusts by turning the gain control, I can make the LED dim with volume up then when something loud is detected, it comes on, it seems the louder the brighter. I don't think the light can get any brighter then what I'm seeing now! Could be wrong.
One thing I haven't done yet is to connect the circuit and monitor the injector, then unplug it to see if the light is still on!
Here are 3 pictures of sound wave of injector firing:
http://ecomodder.com/forum/member-superturnier-albums-injector-opening-delay-picture2854-injector-voltage-signal-injector-sound-signal-resolution-between.html
If I'm reading OZ right he's saying the LED will be maxed out every detection and only the high end of the sound would be amplified.
The gun probe will be easy to use on some injectors, but on others not so easy!, Car's will be hot and running, at the firewall side you will be laying inside the engine compartment, using mirror's and light to find them, probes will have to be bent to get to some of them. This is a cheap way to check them, of course you could take it to a shop and let them do it, at the tune of about 90 to 120 dollars a hour!
I thank all you for the input! I'm all ears!
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Essentially what he's saying is that the circuit has no noise immunity. Every vibration will be amplified equally, which can make distinguishing the injector noise from background noise (other engine sounds, etc) difficult if not impossible.
You've got a pretty good system for pinpointing as close to the source you want to monitor as possible, as far as the rod -> peizo element goes, which is important of course to getting the signal you're actually after.
What he's referring to exploits that further, by making the circuit ignore input that is below a certain threshold, leaving the LED dark most of the time. If the loudest sound available at the input is the injector firing, then this portion of the waveform will be higher than that coming from unwanted background noise. The result is that the LED only fires when this threshold is exceeded.
Depending on what you've got for parts, you may be able to do something like this with little more than what you currently have wired up. There are a couple of ways to go about it...
One, as Oz mentioned, you can set a reference voltage that must be exceeded by the first opamp in order to trigger the second, which fires the LED.
Another is to put some negative bias on the input to the second opamp, which effectively does the same thing, just with a slightly different mechanism. It holds the second opamp in cutoff until the first one puts out a signal high enough to overcome the bias, firing the LED. This approach is a bit easier however if you're using a split supply instead.
Easiest in this case will probably be Oz's approach.
They both will require slightly different configurations in terms of the feedback loop (which is currently set for a gain of 30). You'll likely need to end up with a much higher gain than that in the second opamp in order to make it work effectively.
Steve
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It does a little more than just screening the noise as well.
It means any part of the spike passing the threshold will drive the led to full brilliance for the duration of the spike being above the threshold.... regardless of shape.
In normal amplifier mode (original) the led will light in proportion to the amplitude of the spike... so as it passes the volume setting you have set, it will gradually light up until the max amplitude of the spike has been achieved and then decay accordingly.
With the referenced system, any and all parts of the spike crossing the threshold will drive the led full on for the entire duration of the spike being over the threshold.... so the blink will be full brilliance for the entire width of the spike, more energy (brighter to us) than a spike can drive it with it's own native waveform..... it will be much more lucid in it's visual result..........
..............oztules
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Made another video this time on the bench top, no Sunshine in here! The duration of the blink is a bit fast, that's as slow that I can get the drill to turn, I estimate that it need to turn 10 or 12 times in 1 minute , 200 hits! Should be about 800 rpm's. It's turning about twice that!
Maybe its just a matter of more LED's about 90 degree's apart for sure viewing while in use. Has anyone ever used reflectors?
The batterys in the learning lab were at 8.8v I put some freash ones in now Its at 9.6v! I seen no difference in the brightness of the LED's though!
http://www.flickr.com/photos/18130316@N07/6965039142/in/photostream
Thanks for the input!!!
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I knew this was gonna get complicated.
G-
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YA! Its over my head! I got this mouse trap working! I just don't have the know how, to improve it.!
I think maybe adding some leds might help seeing it operate from any position the gun happens to be in!
I dig the head out of one of these flashlights thay giveaway at harbor freight, it has 9 white leds in it, could this somehow become part of this circuit without alot of altering? Use's 3 AAA bats I see no resistor's being used! It's about the size of a quarter!
What do you guys think?
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I think maybe adding some leds might help seeing it operate from any position the gun happens to be in!
I dig the head out of one of these flashlights thay giveaway at harbor freight, it has 9 white leds in it, could this somehow become part of this circuit without alot of altering?
Well, firstly when you say "any position" - surely you don't need full 360 degrees viewing?
A few suggestions. You can get FAR brighter LEDs than the one you have. Sanding the end will help make it visible from wider angle, but also a frosted-glass or translucent plastic besel will work wonders. Using a pulse-stretcher (a diode, cap and resistor are all thats really required, into your existing opamp) will make longer blinks, that the eye can see more readily.
To answer your specific question about the 9 LED torch - if the torch ran off a 4.5V or 6V supply (3 or 4 AAA cells) and your circuit is running from a 9V battery, you can probably get them to light with very little work. A lower value resistor from the opamp output should do it... just watch that you don't try to pull too much current out of the opamp, or you won't get enough voltage to drive the LEDs hard enough to see any better than the one LED you have now.
Just an observation. Last month I had to modify a large (30' x 15' table) CNC machine to add a "cutter safe" indicator for the operators to know when to change the tool. This is in a factory environment, under normal factory lighting, and the indicator had to be visible from anywhere the operator was likely to be. (That meant a 270 degree viewing angle). I used a single, super-bright green LED (8,000mcd) and operated it on a mere 3mA. I took to the 5mm LED with my grinder to make it quite small and roughed up the face so it would fit entirely inside the plastic cap from an old pilot light/indicator, and glued it in. This thing is about 1/4" diameter, has a chrome mounting thats about 3/8" dia, and total length perhaps 1/2" long. It's more than bright enough to see in any operating condition.
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Can light up an LED with uA.
With nano-power, I always had the best luck with seeing a water-clear red LED.
It is either RED, or it is not.
Example:
Water-clear red led at 12V.
Resistor? Me, from my right big toe to my left index finger.
It is obviously Red.
I'm sending you some water clear red LEDs that are WAY better than the one from RatShak.
G-
[attachimg=1]
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Was going to make a remark something like "I'd know that toe anywhere", but it's been done
many times, so I won't.
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Well, firstly when you say "any position" - surely you don't need full 360 degrees viewing?
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Yes! its important, You do not want to take your attention off what your doing to look for a hard to see LED. The gun will have to be held in all positions to clear things. Front wheel drive auto's will be the bear on the rear bank! Some you wont get to at all, the intake has to come off!
I have tryed the strong LED and sanded it , its not that bright!
Going to try Glens LED's Next!
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I have tryed the strong LED and sanded it , its not that bright!
I said a couple of pages back your ratshack LED is a pitiful excuse for a LED by any recent standards.
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I think the ones I sent are 5,000 or 10,000 MCD.
That $2.19 LED from RatShak is only 300 MCD.
The appearance of my big toe was to show the resistor/cap/diode circuit to keep it On a bit longer will not need to supply much current.
Was going to make a remark something like "I'd know that toe anywhere", but it's been done
many times, so I won't.
I wish I had a prehensile tail too. I don't. Best I can do in some situations is use my toes.
G-