Designing a replacement cruise amp - Page 2 - PeachParts Mercedes-Benz Forum

#16 05-26-2008, 01:48 PM

Quote:

Originally Posted by ForcedInduction

The cruise amp is an analog computer, the switch to digital alone will make a huge cut in the parts count.

OK, but I still don't understand how anything can be hand-made for less than $100 (unless you are paying yourself minimum wage).

300SD81 · #17 05-26-2008, 04:35 PM

I've got most of the circuit designed already, total parts cost is going to be around $15 for the first one (already have most of the parts laying around), closer to $30 for more, I'll probably be willing to sell these for $75 with core (need the connector) preassembled, $50 for a kit with etched circuit board... I'm a highschool student, so really, I'm happy with minimum wage, and I'll be able to get these soldered in less than an hour easily. I'll even post the schematic and source code when I'm done so you can build your own.

I can add some more features too, who would like to have a temp sensor that will use the cruise to raise the idle slightly when its cold so you don't have to hold down the gas?

I'm using a 40-pin PIC microcontroller because I have them laying around, so there are many unused IO pins, how about connecting them all to solder points, so you can use them for anything you want? I'd be willing to custom program anything you want for $25 or less...

I'm doing this for myself as well, so the first one pays for the hours of design work...everything else is just a bonus for me..

bgkast · #18 05-26-2008, 04:38 PM

I would be interested.

MB-Owner-in-ind · #19 05-26-2008, 06:00 PM

I would buy one for earlier year (vacuum servo)

300SD81 · #20 05-26-2008, 09:14 PM

Quote:

Originally Posted by MB-Owner-in-ind

I would buy one for earlier year (vacuum servo)

I'll look into it if you can provide something like the wiring diagram in my first post, I have no idea how the vacuum servo is controlled...

-------------------------------

So it seems I have at least 2 confirmed sales? Turns out I need a new microchip programmer..haven't used mine in months and it got broken... so I need at least 2 to cover my costs for it. I'm going on vacation in a week and won't be able to work on it until I get back and get the new programmer, so the earliest I can have them avaliable is around June 20th.

jkoebel · #21 05-26-2008, 09:23 PM

I'm interested as a curiosity, but honestly, in about 2 weeks I'm planning to write a big check to GDL and re-do my OEM cruise system with OEM parts.

#22 05-26-2008, 09:42 PM

Seriously, it you are going to build this for sale (or for yourself), make sure the design is "fail safe" such that a malfunction (loose contact, etc,) will cause the cruise control to disengage (not to accelerate).

charmalu · #23 05-27-2008, 07:52 AM

Quote:

Originally Posted by Craig

Why not just replace/repair the correct system? I installed a rebuilt amp and a brand new actuator from GDL for about $600 total, it's not really worth trying to reinvent the wheel. You can also install an after-market system, just leave it reversible so the next owner can take it out and put in the correct system.

$600.00

? I use a stick I jamb between the peddle and dash with a string tied to it so I don`t fish around on the floor for it on kick down

.

Sounds like an interesting project, go for it.

Charlie ☺

#24 05-27-2008, 08:21 AM

Quote:

Originally Posted by charmalu

$600.00

? I use a stick I jamb between the peddle and dash with a string tied to it so I don`t fish around on the floor for it on kick down

.

Sounds like an interesting project, go for it.

Charlie ☺

It costs about $250 for a rebuilt amp and about $350 for a new actuator (no point in toasting the new amp with the old actuator), and the whole thing bolts in much less then an hour. Any other option would take more than $600 worth of my time anyway.

mobetta · #25 05-27-2008, 10:43 AM

I would really be interested if it had a high idle setting.................

maybe even pay a few more $.

ConnClark · #26 05-27-2008, 07:55 PM

I thought I might chime in on this thread. Since I now work for a company that assembles, designs, and consults on PCBs I thought I would put in a shameless plug for our services in case you want to do volume production on a prebuilt version.

http://www.njc.com

You probably won't deal with me directly though.

babymog · #27 05-28-2008, 12:38 PM

My King cruise control acts as a high-idle controller when in neutral (using neutral start switch):

Resume = high-idle
Resume = increase idle
Set = decrease idle
Brake = cancel
Drive or Reverse = cancel

Works great on my big CAT in the coach for high-idle, not necessary on the 60x IMO but maybe on a 61x.

Quote:

Originally Posted by 300SD81

I can add some more features too, who would like to have a temp sensor that will use the cruise to raise the idle slightly when its cold so you don't have to hold down the gas?

validius · #28 05-28-2008, 02:23 PM

im confused. Is this the piece for 1985+ cars?

dieseldan44 · #29 05-28-2008, 03:16 PM

My advice as an EE designer...

Be warned: You are entering a rat hole. It's really hard to build stuff this and get it right - especially long term in automotive, even for the pros. We use extensive circuit simulation and testing on stuff like this - and it NEVER works the first time.

Don't think about selling them until you have one that works for a long time. Even then, the liability/tech support/field incidents will take all your time.

That being said, success or failure youll learn so much working on the project itll be worth it, especially if you want to go into EE. Youll make about $1 an hour if you tally up how much time it will take to make a working unit youd trust in your car :-)

You are going to need access to an oscilloscope, and someone to consult on the PCB layout.

Go for it...show this project at an EE job interview and you're hired.

dd

babymog · #30 05-28-2008, 04:18 PM

Not that hard, most of my circuit designs went into production on US and German cars without changes and passed validation testing without trouble.

I like creating, spend some of my free time repairing and re-designing circuits also, it's a hobby and doesn't always need to make money. Same with cars, some of the repairs or mods I make would cost less at a dealer.

If you want to do it, I'd say sell them as "cruise control test devices, not intended for street use" or something similar.

Have fun with the design, just don't set your sights too high on production.