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steven_191 |
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 steven_191 Nearly there...

Joined: 31 May 2009 Karma :   
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 Posted: 17:26 - 17 Jan 2012 Post subject: home made quickshifter |
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inspired by nowhere.elysium's home made dash project i decided to have a play with the Arduino controller.
ive done a bit of messing around and already have various ideas for projects ill get stuck in with, probably all at the same time.
but heres the bike related one.
ive bought myself a £5 hand held digital scales. apparently from hong kong, which arrived today. I took it apart to have a nosey at it. The build of the strain gauge lever isnt what i expected but will benefit me as i can make the parts i need to fix into the gear linkage then bolt is in place. (you will see by the pictures)
so first things first. I gave it a 3v supply and hooked my work bag on it for a test. 10.77kg. so when i have it hooked up i can use that as a general reference. not that im interested in any specific weight value.
ill be taking whatever readings come out of the circuit map it to what i want then use that to pick a pressure at which to cut the ignition for a given amount of time then turn it back on.
my plan is to push onto the gear lever at a constant rate, and this will need a bit of trial and error to get it to a point where it comfortably moves the linkage, cuts the ignition, slots in the gear and turns the ignition back on. this will be in less than a second. maybe less than half a second. we'll wait and see.
the code side of this is very simple.
read the analogue data.
at a specified threshold switch the output
wait
switch the output back
ill also add a small screen in just so i can see the values to help with setting it up.
apparently the arduino can read an analogue input 10,000 times per second so this should be quick enough.
all i need to do is measure the current voltage used for the strain gauge. it runs on 3v so it may be that. and make sure i wire it up right
i have
I+
I-
E+
E-
on the wiring where its soldered to the board
i think e is excite meaning the value output but its connected to red and black which suggests power supply. the other cables,, green and white are what i would assume to be the output and these are labelled i.,
step one, get the digital scales
https://i1112.photobucket.com/albums/k493/steven_191/strain%20gauge%20quickshifter/IMG_1018.jpg
step two, take it to pieces
https://i1112.photobucket.com/albums/k493/steven_191/strain%20gauge%20quickshifter/IMG_1019.jpg
this is the strain gauge. it measures the force applied to the metal bar by its varying amount of 'stretch' on the sensor. (the sensor being a long thin bit of wire that changes resistance when stretched)
https://i1112.photobucket.com/albums/k493/steven_191/strain%20gauge%20quickshifter/IMG_1021.jpg |
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CHR15 |
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 CHR15 Turbo nutter bastard

Joined: 14 Jun 2008 Karma :     
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 Posted: 21:41 - 17 Jan 2012 Post subject: |
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looks very interesting. ____________________ Turbocharged drag thing / project death weapon / GK73A
Ste: I'm not entirely sure how you'd go about verbally abusing someone with a potato but I'm sure it's possible. |
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steven_191 |
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 steven_191 Nearly there...

Joined: 31 May 2009 Karma :   
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nowhere.elysium |
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 nowhere.elysium The Pork Lord

Joined: 02 Mar 2009 Karma :    
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 Posted: 17:07 - 19 Jan 2012 Post subject: |
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Can you post a couple of clear photos of the board, so we can try and figure out how it does what it does?
I'm not claiming any kind of expertise, but I'm guessing that it's mainly the display controller, with a fairly simple reset/calibrate function, and a set of fixed scales for measuring the weight.
Is a microswitch out of the question? ____________________ '10 SV650SF, '83 GS650GT (it lives!), Questionable DIY dash project, 3D Printer project, Lasercutter project |
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steven_191 |
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 steven_191 Nearly there...

Joined: 31 May 2009 Karma :   
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 Posted: 17:57 - 19 Jan 2012 Post subject: |
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a microswitch isnt accurate enough.
well the high quality chinese solder broke off almost instantly just by looking at it.
the strain gauge is no longer connected to the pcb
Ive tested the voltage and resistance across a few wires before it few apart and the only change i saw was that the resistance went from around 1005ohms to 1008ohms. so not much really.
https://i1112.photobucket.com/albums/k493/steven_191/strain%20gauge%20quickshifter/IMG_1022.jpg
ive just soldered it back together and its working again. still havent found any details on how its supposed to work though.
there was a constant 2.2(ish)volts on the red/black so that could be the supply. |
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lllN30lll |
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 lllN30lll World Chat Champion

Joined: 12 Jun 2005 Karma :   
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 Posted: 18:30 - 19 Jan 2012 Post subject: |
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CHR15 |
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 CHR15 Turbo nutter bastard

Joined: 14 Jun 2008 Karma :     
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 Posted: 21:25 - 19 Jan 2012 Post subject: |
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oh hi shervin. ____________________ Turbocharged drag thing / project death weapon / GK73A
Ste: I'm not entirely sure how you'd go about verbally abusing someone with a potato but I'm sure it's possible. |
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steven_191 |
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Joined: 31 May 2009 Karma :   
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steven_191 |
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 steven_191 Nearly there...

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nowhere.elysium |
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 nowhere.elysium The Pork Lord

Joined: 02 Mar 2009 Karma :    
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 Posted: 13:36 - 20 Jan 2012 Post subject: |
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I can't help but think that we should join forces, you know. Combine my dash, with your quickshifter, and work out a bunch of other trick bits for bikes, then just package the whole thing up as a complete trackday/tart-up system.
Having said that, I'm clearly just trying to poach your electronics expertise  ____________________ '10 SV650SF, '83 GS650GT (it lives!), Questionable DIY dash project, 3D Printer project, Lasercutter project |
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steven_191 |
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 steven_191 Nearly there...

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nowhere.elysium |
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 nowhere.elysium The Pork Lord

Joined: 02 Mar 2009 Karma :    
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 Posted: 16:47 - 20 Jan 2012 Post subject: |
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steven_191 wrote: | but anyway, once this lot is done ill send you the details and im sure you can join it up to your dash project easy enough. im using 1 analogue input and 1 digital output. plus another digital input if i want to use this speed compensating idea, but you already have that. |
Cool. Doesn't mean I'm not going to pick your brains periodically, though, along with those of the other main contributors in my thread.
I'm going to be banging heads together with my Dad this weekend, to try and plan out the coding that'll be required for the big bastard version of the dash, along with the I2C coordination and hardware integration.
I'm reckoning on designing and planning out the fullest spec possible, and then trying to make it as completely modular as I can. That way, it's just a matter of whether or not you want the function - if you want it, plug it in; if you don't, then don't.
Once I've got something to show, I'll pm it to you. ____________________ '10 SV650SF, '83 GS650GT (it lives!), Questionable DIY dash project, 3D Printer project, Lasercutter project |
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steven_191 |
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 steven_191 Nearly there...

Joined: 31 May 2009 Karma :   
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 Posted: 17:59 - 20 Jan 2012 Post subject: |
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the only trouble with doing it that way is that whatever wants to be displayed thats not plugged in wont be displayed correctly so you might have odd numbers on the screen.
and if that is the case you will need to compensate with some sort of digital input built into the 'plug' that you may of may not be using and this could turn that area of the dash on or off when it senses its plugged in
also think my op amp is buggered. it measures the different between the two inputs so if you have both inputs from the same source the output =0v. except it doesnt. its 1.68v or something. i connected a potentiometer to one line and the output goes from 5v to 1.6 with nothing in between. definately fucked!!! |
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nowhere.elysium |
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 nowhere.elysium The Pork Lord

Joined: 02 Mar 2009 Karma :    
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Codemonkey |
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 Codemonkey Crazy Courier

Joined: 18 Oct 2009 Karma :  
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steven_191 |
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 steven_191 Nearly there...

Joined: 31 May 2009 Karma :   
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 Posted: 22:42 - 20 Jan 2012 Post subject: |
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Well I've been having a play with it. I connected a resistor back from the output to one of the inputs. I did read a bit about the biasing but I didn't think that applied. I thought I could set it up so that the differential in the two inputs is what gets amplified.
i set it up as per this
https://www.daycounter.com/Calculators/Op-Amp/Op-Amp-Voltage-Calculator.phtml
and used the calculator to work out my resistors.
the op amp im using is a UA741
https://www.datasheetcatalog.org/datasheet/SGSThomsonMicroelectronics/mXssuwx.pdf
and the one i will be getting is
https://www.ti.com/lit/ds/symlink/lm386.pdf
although this isnt an op amp like the UA741.
also i did try having a capacitor between V+ and ground and lastly i was running this from a 9v battery through a 5v+ regulator. so the actually circuit was all 5v+ and ground. no negative voltage.
if you know how i need to set it up that would be helpful. cheers
edit;
i measured the volt out from each pin of the strain gauge to ground and they were both the same even under stress. but when testing between the pins i get around 5mV deflection. i need to amplify!!!! |
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Codemonkey |
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 Codemonkey Crazy Courier

Joined: 18 Oct 2009 Karma :  
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 Posted: 21:11 - 21 Jan 2012 Post subject: |
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You might want to read this
Also, there is a useful program from Linear Technology that will allow you to simulate these things before wasting time building them. Its called LTspice and you can download it here ____________________ Test Passed 10/05/2011 Current bike: XJ6-N |
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steven_191 |
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 steven_191 Nearly there...

Joined: 31 May 2009 Karma :   
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Codemonkey |
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 Codemonkey Crazy Courier

Joined: 18 Oct 2009 Karma :  
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 Posted: 08:04 - 24 Jan 2012 Post subject: |
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It would help if you could post a schematic of what you have. You could use that LTSpice application to draw one then post a screenshot or something ?
As for component values, well it just depends what components!
Really you'd be better off with a single rail Op-Amp. The thing you are using is an audio amplifier and the schematics shown in the datasheets (this one at least https://www.ti.com/lit/ds/symlink/lm386.pdf) are all for amplification of ac signals. You are trying to amplify a dc signal.
The datasheet attached shows a single supply (5V) strain guage amplifier on page 11 (Figure 16). ____________________ Test Passed 10/05/2011 Current bike: XJ6-N |
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steven_191 |
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 steven_191 Nearly there...

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Codemonkey |
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 Codemonkey Crazy Courier

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steven_191 |
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 steven_191 Nearly there...

Joined: 31 May 2009 Karma :   
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 Posted: 21:47 - 24 Jan 2012 Post subject: |
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https://i1112.photobucket.com/albums/k493/steven_191/strain%20gauge%20quickshifter/4bcf757c.jpg
i was talking about the texas instruments pdf. the only thing this is currently missing is where the output is going. I normally connect a lead and clip the volt meter onto it. I also tried a buzzer so that i could ground the other end and make sure it wasnt because of an open circuit. but it was a 6v buzzer and only had about 4.5v coming out. buzzed ones very quickly then nothing. I also tried a small piezo element but that has a slight click when voltage is applied but no sound. |
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nowhere.elysium |
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 nowhere.elysium The Pork Lord

Joined: 02 Mar 2009 Karma :    
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steven_191 |
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 steven_191 Nearly there...

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nowhere.elysium |
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 nowhere.elysium The Pork Lord

Joined: 02 Mar 2009 Karma :    
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 Posted: 15:26 - 25 Jan 2012 Post subject: |
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OK - firstly, Codemonkey's advice of using spice is good. Take heed of it.
Secondly, from what I can see, this is how you've wired this up:
https://farm8.staticflickr.com/7165/6760450911_c3f8dd9022.jpg
I've just noticed (after running your image through a massive zoom factor) that I've put the notch at the wrong end of the chip.
However, would it not make sense to isolate the input from the variable resistor from the output from the chip?
If you could give us a more accurate diagram of what you've got, it'd help. I'm far from knowing what I'm on about when it comes to electronics, but it's easier to read diagrams than to decipher someone else's breadboard
As an afterthought; does a negative voltage input have to be from a separate inverted source, or can it just be hooked into ground? I've never been sure. ____________________ '10 SV650SF, '83 GS650GT (it lives!), Questionable DIY dash project, 3D Printer project, Lasercutter project |
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Old Thread Alert!
The last post was made 13 years, 274 days ago. Instead of replying here, would creating a new thread be more useful? |
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