Laying out my own PCB - what 'options' are useful? - Page 2 - Fuel Economy, Hypermiling, EcoModding News and Forum

mpgx2 · 07-06-2010, 01:45 AM

thanks for the explanation.. I've never done it before but now feel encouraged to try.

JellyBeanDriver · 07-06-2010, 11:05 PM

There are other methods. One is to laserprint onto special (or not so special) paper, then iron it onto a cleaned PCB to transfer the toner to the board. Soak in water to remove the paper, then etch the board. The toner is a etch stop.

I've never gotten good at that method. The nice thing about the photo method is it's easy to crank out another board, or many boards, with consistent quality.

I'm going to put a socket on my LCD instead of hard soldering it to my board. This will be a test bed and I suspect I'll need/want to take it apart and change component values.

JellyBeanDriver · 07-13-2010, 01:21 AM

Programmed the chip, installed it this past weekend.

Today was the first day of driving with an MPG meter in my face, and boy was it a learning experience.

Taking off in each gear I learned something that wasn't obvious to me before - higher gears get better gas mileage!
Seems obvious but I discovered it a different way. Watching the 'instant' MPG readout, if I hold the gas pedal steady at about the same throttle position in each gear, the MPG is ~ 7-8 for 1st, 15 for 2nd, 24 for 3rd, etc. This is when the engine is loaded and not just cruising in a gear. Thought the MPG in 1st and 2nd was low until I figured out why. Duh!

Found that drafting works! And I don't have to be that close to the trailer in front of me.

Coasting, even at low low speeds, gives me GREAT mpg's! Coasting in gear I can see the injector cutout working as the MPG meter registers 99999 when it happens.

Slight inclines up and down in the road, slight throttle changes, all are reflected in quite large instant MPG changes.

Drove a LOT mellower today - trying to see how high I can get the MPG up on this tank of gas. Don't know if I'm calibrated yet but regardless this device is working and giving me instand feedback on my driving.

Display is easy to read even in reasonably direct sunlight. I'm using a STN (supertwist) display so the characters are crisp and dense and has a wide viewing angle. Trippy to look at it when the sunlight is coming in as the characters are hovering on a clear piece of glass.

JellyBeanDriver · 07-16-2010, 12:43 AM

Just refilled the tank. 51.8 MPG on that tank - best ever. Lots of drafting, lots of coasting whenever I could. Still have lots to learn on how to get the best gas mileage.

My best before this was 48.3 MPG and that was with 12" tires and original brakes/knuckles, but average was more like 46MPG.

Best after my brake/knuckle/13" tire upgrade was 45.5MPG, but average more like 44-45mpg

JellyBeanDriver · 07-25-2010, 11:12 PM

Satisfied with the operation I redid the PCB layout, cleaned it up a bit and put a terminal block on for wire attachment.

JellyBeanDriver · 03-29-2012, 01:28 AM

Ends up I'm going to make a bunch of these due to requests on GMF. Board is out being fab'd, should have it next week.

Pretty much the same board as shown in my posts above but with added traces to feed the 2 unused analog inputs on the ATMega for those that want to add other features. Also added in a 6 pin ICSP header for programming.

Only comes with the switches shown but I do have solder pads for adding external switches (you can cut the bats off the existing switches if you don't want to use them).

Will be assembled - I laid out the board for my ease of assembly and cost so I'm using SMT parts, some thru hole where the parts are cheaper.

Stay tuned (I don't frequent this page that often)
(oh, and I need to update my signature - my metro is up to 411,000 miles on the original engine).