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tfunder
tfunder
8/31/21 4:46 p.m.

Hi all,

This is my first post. I have been lurking for (quite) some time because whenever I'm goooogling for something racing+diy I tend to end up here - so I though it was time for a bit of pay-it-back :-)

Disclaimer: I am an IT guy, no even worse I'm an IT manager ;-) so by continuing reading you accept that I have absolutely no clue what I'm doing. This could break, burn, short or disperse radiation on an unknown wavelength. Also I am not offering 24x7 support, in fact please consider this 'grabware'. You grab it, and see if you can make it work for your purpose.

That being said, I'd try to help if I can ;-)

Background: I was looking for some corner weights, but was not able to find anything suitable (read:cheap) enough in my  part of the world. So I went online and found some cheap(ish) parcel scales from eBay. They are only rated for 300kg, but since my car is in the 975-1050kg range that was ok. AFAIK most 'budget' scales are constructed more or less similar so I would assume other rated scales would work just as fine.

Solution: I found out that cutting the original wiring of the scale, replacing it with 4x HX711 load cell amplifiers connected to an Arduino worked perfect. Adding in some LCD displays, wiring,  network cables, 3D printed parts and a plastic box and I ended up with this:

(With my foot on FR scale just to show some numbers)

I'd be happy to share wiring diagrams, arduino code etc. if anyone is interested. 

I had some of the parts, connectors, wiring etc, but estimated cost is around €335/USD400.

 

alfadriver
alfadriver MegaDork
8/31/21 4:49 p.m.

Where did you find load cells?  That's really cool.

APEowner
APEowner GRM+ Memberand SuperDork
8/31/21 4:51 p.m.

Welcome. That's a heck of a first post and a very cool project.  I'm sure I speak for others when I say that we'd like to see whatever you're willing to share.

tfunder
tfunder New Reader
8/31/21 4:51 p.m.

Load cells are in the scales ;-)

Edit: this is how the scales look like out-of-box. I cut the black DB9 cable and solder the 4 wires coming out of the bottom of the small green print to the HX711. Connect HX711 to the Arduino, calibrate the scale (lot's of guides online, ie. https://circuits4you.com/2016/11/25/hx711-arduino-load-cell/)

Repeat 3 more times.

 

tfunder
tfunder New Reader
8/31/21 5:08 p.m.

In reply to APEowner :

Here's wiring diagrams and Arduino code (v.09x) for starts. 

https://github.com/tfunder/Corner-Weights

 

 

bgkast
bgkast GRM+ Memberand PowerDork
8/31/21 5:19 p.m.

This is awesome, thanks for sharing! I just started messing with an Arduino with my daughter.

APEowner
APEowner GRM+ Memberand SuperDork
8/31/21 5:32 p.m.
tfunder said:

In reply to APEowner :

Here's wiring diagrams and Arduino code (v.09x) for starts. 

https://github.com/tfunder/Corner-Weights

 

 

Cool.  Thanks.  I've never messed with an Arduino.  Am I correct in assuming that LiquidCrystal_I2C.h is a library module?

tfunder
tfunder New Reader
8/31/21 6:01 p.m.

In reply to APEowner :

Yes :-) Ctrl+Shift+I in the Arduino dev tool to open "Manage Libraries" and add.

..and you also need to add the "HX711.h" library.

californiamilleghia
californiamilleghia SuperDork
8/31/21 6:12 p.m.

GREAT :)

What other things have you built ?

 

tfunder
tfunder New Reader
9/1/21 12:21 a.m.

In reply to californiamilleghia :

I have been playing around with Arduinos, but this is actually one of my first "finished" projects.

I do have a breadboard-prototype of a servo "Throttle Blipper" with configurable timing and amount ;-) I'll share if I get it done ;-)

MadScientistMatt
MadScientistMatt UltimaDork
9/1/21 6:35 a.m.

Nice work!

2002maniac
2002maniac Dork
9/1/21 12:20 p.m.

nice work!

sevenracer
sevenracer Reader
9/1/21 9:34 p.m.

Nice work indeed.

 

Years ago, I briefly entertained building something similar with a USB analog i/o board plugged into a PC, but I couldn't find reasonably priced load cells that were up to the task. These days, there's probably something suitable and cheap out on Alibaba or similar.

03Panther
03Panther UltraDork
9/1/21 11:23 p.m.

In reply to tfunder :

Love the disclaimer! You're gonna fit right in.

I'm a Peterson (yes I know, its spelled wrong! Typo on a birth certificate), a Mickelsen, a Jacobson... and.... a Garret / Hicks. Dad's father, from Denmark, jumped ship as a wee lad of 14 or so in NYC. Dad's mom came over at 16 to be an au'pare (however ya spell that babysitter word). Mom's Dad was born here in 1919 to Danish immigrants, and Mom's mom's family had been in Williamsburg since the beginning.

Anyway welcome from a square head (and proud of it!)

tfunder
tfunder New Reader
9/2/21 1:38 a.m.

In reply to 03Panther :

Thanks :-) You could actually argue your name is spelled as intended "Son of Peter" just 'translated' :-) 

 

Flerbizky
Flerbizky GRM+ Memberand None
3/26/23 6:32 a.m.

In reply to tfunder :

Sorry for Zombiefying an old thread - just want to make sure.

Is it safe to assume that this is the way you've wired the loadcells in the scales?

Thank you.

tfunder
tfunder New Reader
3/26/23 7:07 a.m.

I used this :-)

 

Flerbizky
Flerbizky GRM+ Memberand New Reader
3/26/23 1:29 p.m.
tfunder said:

I used this :-)

Thank you - same as the one I found on instructibles. Parts are on their merry way - can't wait to see how bad it is ;)

 

 

Brotus7
Brotus7 Dork
3/26/23 5:11 p.m.

For the Arduino illiterate, can you paste in your sketch? I'm a little bit aways from needing corner scales, but I'm saving this thread.

L5wolvesf
L5wolvesf Dork
3/26/23 10:22 p.m.
Brotus7 said:

For the Arduino illiterate, can you paste in your sketch? I'm a little bit aways from needing corner scales, but I'm saving this thread.

A link to the scales used would be good too 

kb58
kb58 UltraDork
3/26/23 10:46 p.m.

Back when I was a teen, microprocessor chips (in any form) were just beginning to appear. To do a project like this meant researching all the parts, ensuring that they could talk to each other, creating the schematic, making your own PC or wirewrap board, and doing ALL the coding yourself. The upside is that it was excellent self-education to become an engineer. The downside being it took a while to build something, and it wasn't cheap. Now it's almost too easy, and I wonder how much engineers-to-be get out of doing an Arduino project, especially ones with library functions. There's the interfacing... if not already done for you, and that's about it. Oh well, such is progress.

alfadriver
alfadriver MegaDork
3/26/23 11:16 p.m.

In reply to kb58 :

As an engineer who has tried and failed doing arduino projects- it's not really as easy as it seems.  I've even used someone else's program, and it would not compile and I had no idea why.  

For a programmer, they are really nice- we've used them at work a few time- commercial grade ones.  

If I were racing, I would probably give this project a shot, though.  Especially with someone here who has done it.  Seeing some of the responses on the arduino board made me hesitate to ask questions.

DirtyBird222
DirtyBird222 PowerDork
3/27/23 2:43 p.m.
alfadriver said:

In reply to kb58 :

As an engineer who has tried and failed doing arduino projects- it's not really as easy as it seems.  I've even used someone else's program, and it would not compile and I had no idea why.  

For a programmer, they are really nice- we've used them at work a few time- commercial grade ones.  

If I were racing, I would probably give this project a shot, though.  Especially with someone here who has done it.  Seeing some of the responses on the arduino board made me hesitate to ask questions.

I've had great success in using them for anything but racing. I tried following someones guide on how to use one for a homebrew shift light. Gathered everything I needed, modified the code a bit to adjust for the tach signal coming out of the Honda distributor, and it would work on the bench every single time. Threw it in the car and it would work on start up and just casually revving. Sebring would destroy the arduino in a lap no matter how many different ways I tried sealing it and mounting it  but that was years ago.

I might try this project, looks pretty simple and thank you for the write up! 

kb58
kb58 UltraDork
3/27/23 8:02 p.m.

EMI, heat, and vibration do in many circuits put onto a race track.

Tyler H
Tyler H GRM+ Memberand UberDork
3/28/23 3:34 p.m.

I used an Arduino Uno to build a 3' tall digital tach with a VTEC YO light mounted to the roof of our Lemons car 10+ years ago.  It survived the rigors of racing much better than the D16Z6 engine did, plus I could see who was busting our 6500 RPM 'soft ceiling' coming down the front straight.  One of the keys was using a pretty beefy transistor for each of the outputs to shield the microcontroller from directly driving anything.  I also shielded the input and wrote in some smoothing on the noisy input side of the whole shebang.

But yeah, Turn 17 at Sebring will kill just about anything.

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