Load cell Project: I pay cash.

[HatTrick]

Hello,
I did a search for load cell circuits and found an old post from mrseaton about load cells.
I need a board built for a load cell from a bathroom scale, that will display weight on an LCD display.
The features are,
1. an on/off switch,
2. the scale must immediately read the load cell and display the weight immediately, I do not care about it zeroing, it doesn't even have to be that accurate
3. it must continually read the weight as it changes, like 25 samples a second
4. you must provide a schematic of the lay out of the board so it can be mass produced.
The pay for this project is $1,500 U.S.D.
I live in San Antoino Texas. My cell is 210-845-9855 My name is Scott. My email is maxrepmail@yahoo.com
This device will go on an invention similar to this one **broken link removed**
That is my invention and that is me in the video describing it. I prefer to work with someone local to me, but that is not required. Contact me and we can work out any details or concerns.

 

[Pommie]

Try to get hold of the April 2009 issue of Elektor. It has exactly the project you describe. Found a **broken link removed**.

Mike.

 

[HatTrick]

That article says the board will interface with a PC to show the load profile vs. time. That is cool but a little more involved than I need. I couldn't access the page right away. I think I need to be a VIP or something.

That one is dealing with kitchen scale which go up to a pound of force or so. I need something to go to 300 lbs. or so.

 

[Pommie]

The article explains how the load cell works and has an interface circuit. The type/size of scale/load cell is immaterial, the interface is the same. I just thought it would give you a starting place.

You can pay a small fee to download the article.

Mike.

 

[HatTrick]

I really don't have the time to try to do it myself. I was hoping someone had already done it and could do it again rahter easily.

 

[Pommie]

Well, if someone wants to make $1500 then that article is a good place to start.

Mike.

 

[Rolf]

Hello,
I did a search for load cell circuits and found an old post from mrseaton about load cells.
I need a board built for a load cell from a bathroom scale, that will display weight on an LCD display.
The features are,
1. an on/off switch,
2. the scale must immediately read the load cell and display the weight immediately, I do not care about it zeroing, it doesn't even have to be that accurate
3. it must continually read the weight as it changes, like 25 samples a second
4. you must provide a schematic of the lay out of the board so it can be mass produced.
The pay for this project is $1,500 U.S.D.
I live in San Antoino Texas. My cell is 210-845-9855 My name is Scott. My email is maxrepmail@yahoo.com
This device will go on an invention similar to this one **broken link removed**
That is my invention and that is me in the video describing it. I prefer to work with someone local to me, but that is not required. Contact me and we can work out any details or concerns.

Something like this?
Amazon.com: EatSmart Digital Bathroom Scale w/ Extra Large Backlit 3.5" Display and Oversize Platform: Health & Personal Care

 

[HatTrick]

Rolf-yes it is very close to that. that has multiple load cells. I need one that has just one and that handles 300 lbs. directly onto the load cell. The problem with that particular scale is it has 4. The problem with the one's with just one is they are levered inside to balance the weight from 4 corners and the lever is a 20:1. So when you barley push on the load cell it is quickly maxed out showing 300 lbs. when I am only pushing down with 15 lbs. of force.

 

[HatTrick]

I am in contact with someone from this site that is local to me. Hopefully I am going to meet with him this weekend. Please post your interest in the project here. If it doesn't work out for whatever reason, I will immediately be looking for someone else. The clock is ticking for me, I have about 3 weeks before a trade show. thank you for your interest. When he is finished we will post some pics and a diagram of the project. I haven't really perused this site yet, the stuff is way over my head, I participate in a sailboat forum and we always post pics of our boats and projects. So if it is cool with the guy building the board we will psot them here.

 

[Rolf]

Rolf-yes it is very close to that. that has multiple load cells. I need one that has just one and that handles 300 lbs. directly onto the load cell. The problem with that particular scale is it has 4. The problem with the one's with just one is they are levered inside to balance the weight from 4 corners and the lever is a 20:1. So when you barley push on the load cell it is quickly maxed out showing 300 lbs. when I am only pushing down with 15 lbs. of force.

You can decrease the the force on the load cell by using a several pulleys, each pulley would decrease the output by 50%. This of cause must be engineered in reverse of a "normal" pulley system.

 

[Boncuk]

I suggest to purchase the balance and salvage the sensors for your application.

I checked strain sensors and most of them are <50US$.

 

[HatTrick]

That is the plan for now. We will buy cheap bathroom scales and take the load cells out. We can get a scale for $20 USD. So $5 a piece for load cells. The cheapest load cell I found on the internet was $500 USD. That makes no sense to me.
Rolf-I am leveraging the load cell with a lever but only at 2:1. Actually I am leveraging the brake pad so the force applied is halved but the output force is the same. So the load cell only gets half the force it was.

 

[HatTrick]

I wanted to update you on this project. A guy on this forum from Austin Texas built the board for me and he did a great job. It worked perfectly.
It is on this machine. Run Rocket We haven't updated the pictures yet but it will be shown on there soon.