[Robotgroup] Printing PCBs

[Eric Lundquist]

I don't want to discourage anyone from building their own boards but
for $17.95 + shipping you can get a complete L298 motor controller kit
here. It includes circuit board plus parts:

http://www.hobbyengineering.com/H1918.html

- Eric


On 5/7/07, Clendon Gibson <bsandyman at yahoo.com> wrote:
> Ok,
>
> I now have multiple offers to help with cutting and drilling the etched boards. I am working out swaps with them for the favor of their time and effort.
>
> Now the only thing holding me back is the need for pledges to cover the cost of the photo-etch gear. So I am going to get a definite number for the price from Frys. As a ballpark I am thinking $10 for a drilled cut and etched board. You would need to add the parts and solder. (Unless someone would care to exchange soldering time and expertise for something? Maybe brisket at Pok-e-Joes?)
>
> Now I know that you roboteers NEED a dual H-Bridge capable of driving 50V at 2A! Heck I am getting two, one to show and one to blow.
>
> If I can get pledges for 6 or 7 boards I will consider it worth my time, get the gear and make the boards.
>
> ----- Original Message ----
> From: Gray Mack <gray_mack at yahoo.com>
> To: The Robot Group Mailing List <robotgroup at puremagic.com>
> Sent: Monday, May 7, 2007 11:25:02 AM
> Subject: Re: [Robotgroup] Printing PCBs
>
> I highly recommend the photo etch process, once you get the development process down the results are very good. It requires pre-sensitized boards.  Frys sells them for I think $13 for a 6x9 +$2 for double sided. You need a bottle of developer (maybe $10) and the development light kit (maybe $30). print the tracings onto a transparency. Expose the board to light with the transparency on it. Develop the board and wash it. Then it etches in ferric chloride just like any other trace resist etching.
> I have a dremel press, the only thing I dont have is a way to cut the boards (best done after etching since you cant expose this kind of board to light before hand).
> If you want to defray the costs I recommend getting a signup list of who wants the boards beforehand. Its hard to tell how many H-Bridges are needed by TRG folks.
>
> My experience with this chip is that it will drive a 6v battery/motor from a 5v logic supply and run cordless screwdriver motors. I didnt try letting the battery sag down below that or stalling the motor outputs to see if it went over 2 amps or whatever the max was. To use the sense feedback on the chip you have to use a current shunt, I dont know if something like a fuse will work for this. Overall it seems like a good circuit to have laying around on your bench.
>
> -Gray
>
> ----- Original Message ----
> From: Clendon Gibson <bsandyman at yahoo.com>
> To: Austin Robotgroup Mailing List <robotgroup at puremagic.com>
> Sent: Monday, May 7, 2007 9:54:27 AM
> Subject: [Robotgroup] Printing PCBs
>
>
> I am thinking of getting the gear together to make single or maybe double sided PCB boards. The techniques I was taught back in the day was to use copper boards coated with photo-resist. It looks like I can get a complete kit of this including some starter boards for $70-$80.
>
> In particular I am wanting to make this board for the L298 dual H-Bridge:
>
> http://www.dprg.org/projects/1998-04a/
>
> I am thinking that if I can sell 7 or 8 of these boards to interested RG members for maybe $10 a piece I can cover my costs and provide a useful service to the group.
>
> What I don't have is a drill press or a means of cutting the finished boards. So would anyone be willing to provide the drilling and cutting in return for a board or two, or some fee?
>
> Of course some members may be happy to do the cutting and drilling themselves.
>
> If there is interest please let me know. I would also be open to printing boards from anything you can print on a transparency.
>
>
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