I am doing a personal project I need to create a electronic saximeter. (Normally cost 7000US)
The system is used in civil engineering to record the number of hit a hammer make onto a pile. These noise are extremely loud so loud you have to use ear protection when working around the environment.
I need to create a system that will measure the number of hits (tuned to a certain dB so I can filter out background noise) so everytime the hammer hits a pile it will record the hit. So it would basically count the number of hits.
I need to find a high quality microphone to do this for me. Microphone must be able to measure dB within range of 160dB-230dB.
Any reason you can't use an ordinary microphone and put it in an insulated enclosure?
Or a very insensitive accelerometer?
The device is not mounted on the hammer the forces produced by the hammer along any part of the hammer is so much that it will destroy anything that at least not 5 inch thick steel.
The hammer ways about 10tons. and it lifted by a crane.
someone on the ground hold the device and the device count the number of hits. Every X feet the operator would press a button and it will record the number of hits per feet.
So basically I am counting the number of hits per X feet. I just need a microphone that can withstand dB in that range and be able to give good reading. I have worked with ultrasonic sensor before but I don't think that small diaphragm can handle that kind of noise.
No i can't use an acceleration the vibration alone would break the components and certain IC have mechanical shock rating on them.
How about a Piezo element? They respond well to shock waves, and can probably take that kind of jolt and survive… Seems to me that what you are dealing with is more of a shock wave than it is sound per se.
Piezo elements give off voltage when they are flexed, impacted, or otherwise strained- probably perfect for the sensing of those impacts. That, and they are DIRT cheap fornthe common disc type, which will probably suffice.
Well I can tell you when you stand there you don't really feel a sound or shock wave. I stood about 30 feet from one and all that shakes is the ground because of the vibration.
I have owned a saximeter before the only problem I don't feel like spending 7000us for a new one.
I'll look into the piezo element thanks by the way
I'd say it's likely to be the cheapest and easiest solution.. I think a condenser element micxrophone is just going to break at those levels. Seeing as the piezo element would probably be able to detect either the loud sound or the vibration, it would be my first choice to try, particularly as they are very cheap and there's many notes out there on how to interface them.
I worried that when the operator taps the device to record the number of feet the pile has sunk it will create an extra reading on the pizeo meter. Since the operator hold the device every x number feet the pile sink he press a button that records it on the device.
So basically if he does that and the piezo meter think it actually a hit it will record false data.
That could be handled all sorts of ways, but the easiest would be a simple switch telling the Arduino to not count.. Toggle off, throw it across the yard, no change. Place it down and turnback on.
I think you miss understand how the system works. The Ardunio must never stop counting it must count all the time. I am recroding count per hit or counts per blow so I will know how far the pile has been driven into the ground.
The only way to measure the number of feet you sink is to have someone look at the pile while it sinking, the pile has marking on it the marking are made before the pile is raised by the crane and these marking arn't made in any special way someone would either just draw a mark on it every 6 feet or so. Every time the piles sink 6 feet he would press a button on the device which would record it. So I would get hit per blow as a unit. I have owned one of these before it's just that they are very expensive to buy they cost 7000us or so and the type of piles we drive into the ground at our company doesn't require those advance one. Usually the pile we drive are driven in relativity hard mud so the sound is very unique. Most these meter compensate for oil rig pile driving.
I don't need one of those.
So yes I would need someone to press a button because there no one way to measure the amount of feet the pile has sunk. And i cannot put anything on the pile it will be destroyed buy the impact hammer the amount of force the hammer generates make the ground about 30feet away feel like a earthquake trimmer.
I can't turn off the device because the hammer doesn't stop until the pile is driven all the way into the ground. I need it to keep recording until the entire pile is driven into the ground every few minutes the pile would have sunk to 6 feet the operators just press a button.
Well, using the SOUND, just about any microphone would pick it up. Muffled, baffled, just about any of the mic modules you might find on ebay or SparkFun would work fine for picking up the impacts.
How about adding a rf remote, that way the operator doesn't have to actually touch the impact counter at all?
When the six feet passes, click a keyfob kind of thing (cheap and easy to use) and the device makes a note of it.
So, are you going to want to store the data? SD card? or just display it on an LCD?
If I understand right, the device keeps track of the impacts and the operator clicks a tally button when six feet have passed. I suppose this tracks how far each impact is driving in the piling, you would just display the "current" impacts per tally (six feet).. right?
No i will store it. But that not hard I have done multiple projects with arduino and android. I just have not worked with may microphone and thus I don't know any good brands and so on.
I know how to build the circuitry I already have a rough design.
Can you not put a sensors somewhere else on the driving rig? There must be plenty of components that move in relation to a hit.
Or are you not able to add stuff to the rig?
You may consider separating the distance measurement from the counter. In addition if you use multiple sensors and identify an impact (strike) profile for all the sensors it will be harder to get a false reading when 2 or more sensors indicate that a strike has occurred. The strike sensor might be best stored in an isolated place (ie operator cabin). Both instruments may act as a slave to a a data collector or the data collector. You may want the distance measure to display the strikes (collected from the multi-sensor counter). Perhaps bluetooth might be an option to enable the display and transmitting of values.
A regular microphone and a simple preamp/amp circuit is required..
I bet what gives the high gain reading of the 7000$ unit boils down to the circuit used amd ehat kind of filtering it's got..
You could use an opamp or transistors and a cheap mic...