Sensors

Help!

I'm trying to build something which will measure the force something like a
hammer hits an object. So, for example, I hit this thing and it says 78.4
PSI

I'm not a technical person whatsoever so when I search on line, I'm getting
all kinds of different stuff from industrial to engineered for space travel.

I'm looking for something cheap that I can experiment with.

And before the jokes come, I know I can get *that* in the binary groups.

Please post questions, thanks in advance for your guidence.

Studio

 

Thanks.

I guess I was thinking like $100 USD.

When I searched on "impulse measurment techniques" I am getting fairly
technical things, research papers and such.

Can you help me find a particular website?

 

If you are looking for sensors then industrial sites are the place to
look but "something cheap" depends on your definition.

What you are describing though is not just a sensor but a complete
instrument. If you are a looking for something that measures the force
with which an oboject is being hit you might refine your search to
impulse measurment techniques.

 

If you are looking for sensors then industrial sites are the place to
look but "something cheap" depends on your definition of cheap.

What you are describing though is not justIf you are looking for sensors
then industrial sites are the place to look but "something cheap"
depends on your definition.

What you are describing though is not just a sensor but a complete
instrument. If you are a looking for something that measures the force
with which an oboject is being hit you might refine your search to
impulse measurment techniques. a sensor but a complete instrument. If
you are a looking for something that measures the force with which an
object is being hit you might refine your search to impulse measurement
techniques.

Finding something that will do the job without being destroyed could be
a challenge an accelerometer attached to (or embedded in) an object of
known mass might be a good start.



Some sites:
http://www.dytran.com/
http://www.thomasregisterdirectory.com/load_cells/force_measuring_instruments_0031902_1.html

 

You are too quick for me I was in the process of modifying this when you
responded.

 

If I understand you correctly, then you might consider
putting an accelerometer on the hammer. That won't
tell PSI because you won't know the contact area,
but it may allow you to derive a useful number.

What is it exactly you are trying to do?


Bob Masta
dqatechATdaqartaDOTcom

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com

 

Something simple like a pedulum bob and a scale to see how far it is
displaced when hit?
Phil

 

Analog Devices have integrated circuit MEMS accelerometers on their site.
They use a mass and spring microengineered out of silicon to measure
accelerations of up to about 50 g.

Or you could put a sheet of rubber between two metal plates and measure
the change in capacitance?

 

What's that Lassie? You say that studio fell down the old
sci.electronics.basics mine and will die if we don't mount a rescue by
Mon, 16 Aug 2004 21:49:58 -0400:

I think what you want is a pressure transducer. They can be had from
surplus stores. I think I saw them at C+H sales.

That, plus a small hydraulic cylinder, will give you an analog signal
proportional to the force applied to the piston rod of the hydraulic
cylinder.

The transducer works like the sending unit on your car's oil pressure
gauge. You will need something to store/read the output if you need
to see the results of a fast event like your hammer example. For
slower events a DMM should be fine. You will need to test it with a
known force, and you will need to chose a cylinder that has the proper
bore(area) to create the PSI that the transducer is rated for.

Good luck.
Dan H.

 

I've never used 'em, but how about a strain gauge attached to the side
of a rod with known (or measurable) elasticity? Like a nail maybe
You could either integrate the output to get the total impulse delivered,
or peak-detect it to get the maximum force.

 

--You might try posting this to rec.crafts.metalworking; there are
quite a few folks up to strange stuff like this over there..

 

It depends what you are trying to do, and just how much force you expect
to measure. Here are a frew ideas:_

1. Load cell. A bit expensive to bash, but protect with a large plate.
read the output faster than you would a load cell in, say a weighing
scale. Analog Devices, and Maxim, among others have dedicated devices
for converting and amplifying load cell signals.

2. Known mass with accelerometer on surface of known coefficient of
friction.

3. piezo element, protected. measure the voltage spike.

4. accelerometer in flexible lever, like the old school ruler twanging.

5. as above with piezo

6. Accelerometer on the object your bashing with. Know the mass of the
object and the acceleration allows you to derive force.

7. lever element arranged to electrically detect moment of contact with
the object. A microswitch under neath, or laser beam, allows you to
determine the force the lever was struck with, based upon the time it
took from impact to switch operation.

Cheers

Al

 

The resistance of the black foame used for shipping devices sensitive to
electrostatics depends on pressure. A little bit from the last shipment
of ICs is the cheapest sensor I know of.