Let the breadboarding begin...

[Justin B.]

I just received my "care package" containing differential pressure sensors, op-amps, and other such bits of wizardry so I guess I'll drag out the 'scope and start breadboarding a test/prototype circuit for the "Twinmax" replacement.  Besides using a common DMM for the readout I'm also thinking about maybe a few LEDs...

[weasel01]

I'm excited to see what you come up with!!

If you dont mind my asking what is your initial plan of attack?

Will it be an analog comparator? or ccp on an mcu?

Or would it be straight resistive measurement? or other?

The ability to adjust sensitivity and fast tracking would be nice.

[Justin B.]

The final "black box" will just output a voltage that the user will monitor with their DMM.  I am using a pot on my test unit so I can set the "zero" point anywhere between 1 and 11 volts (using 12V supply) and usually set it at 5 volts.  When one side is lower pressure the voltage drops (below the zero setpoint)  and when the other side is lower the voltage rises above the setpoint.

This works fine on the bench so I will now need to get a chunk of perfboard and make a more portable one that I can hook up to a bike to see what the wild pulsing will do to it!  I'll probably need to use an RC network of some sorts to dampen or smooth the output of the transducer before it gets to the op-amp stage...

[weasel01]

Now will this be a device that is used in the garage or will you be able to ride with it?

It would be awesome to tune with realtime feedback.

[Justin B.]

Both. totally portable and will run off the vehicle battery instead of an internal battery.

[weasel01]

Excellent! Good luck with the prototyping.

I love to design with electronics and I do it a lot.
I used to go from breadboard to a pcb house like "pcb express" for my designs but the cost is extreme especially if it's a developement and you are constantly improving or expanding the design.

So to cut costs and because I am a true tinker-a-holic I got interested in CNC and designed and built my own actually 2 now and almost 3.

My first machine is a gantry style mill that I use for everything from isolation milling of PCB's to cutting RC airplane and helicopter parts to complex patterns that I then use with router table.
 I keep this machine in my home garage.

The second machine is a converted Enco brand round column milling machine and it is used for much larger metal work and precision repeated drilling keep that one out at the shop.

And I have a small (9 x 20) Jet lathe that I am slowly converting to CNC hopefully I'll get hat one going this winter (also in my garage).

If you prototype much it's well worth while and surprisingly easy to do.

[weasel01]

I went out to the garage and took some pictures of my cnc setup.

The first picture is the dust confinement box

The 2nd is inside ...the router head or spindle travels 24" x 48" and up about 6"

The 3rd picture is a standard blank pcb and the method is called isolation milling as the it cuts the traces in little islands.

That particular pcb is version 1 of my homemade Segway human transporter.

[Justin B.]

That's pretty cool, I've been trying to con. err talk, Suraklyn into building a CNC router but so far no luck.  I have a small CNClathe (based on a Sherline, I think) that I play around with but nothing serious...

[Bengt_Phorqs]

There are those of us that are less technically proficient but like to keep up with the dialog here.  For my edification what is "breadboarding", and what is a "DMM".  I understand a manometer and all the lathe/mill talk, but I'm just trying to follow where you're going with this.  

And, if you build it, will I want to buy one? :-/

[Bob_Roller]

Bread-boarding, is the assembly of a prototype circuit board, it can be adjusted during assembly without using of solder joints, to solve any unforeseen problems , DMM is short for a digital multimeter .

If you see a term you don't recognize, go to wikipedia, and usually you can get a not overly technical explanation of the term or phrase .

[Justin B.]

Bob covered it...

I have the test circuit soldered together and maybe this coming weekend I'll finish putting it in a box (so it won't fall apart) and try it out on a "live" bike instead of a Mity-Vac.

[Bengt_Phorqs]

Thanks, I thought it might be something like that.

[weasel01]

I'm really curious about how the carbs react  (if different or not) under a real world load.

[weasel01]

The other thing that I'm really curious about is why does the idle rpm change from cold  to operating temp?

[Justin B.]

Oil warms up and gets thinner, fuel vapor doesn't tend to "cling" to intake runner walls, lots of things contribute...