Another USB relay controller

Rickertsen2 · 05-21-2006, 03:13 PM

I'm working on another USB relay controller. It will be 5 channels of 15A SPDT relays and will be bus powered, meaning no 12v connections necessary. I have a board made so far(sorry no pics) and am waiting to get my hands on the parts. From there i will write the code, and when i am done, i will create some instruction on how you can make your own. All the parts are about half the price of a phidget, but you must not be afraid of soldering (including SMD parts) and making your own circuit board. I may look into making a kit which is something i know zero about.

Code:

U S B   5 c h   S P D T   R e l a y   c o n t r o l l e r   B O M
			
Desc				Subtotal	Qty	Digi-Key
PIC18F2450-I/SP			$6.53		1	PIC18F2450-I/SP-ND
USB conn			$1.92		1	WM17113-ND
Circuit Board 3x4.5		$4.60		1	PC51-ND
MRA4003T3G Diodes		$0.26		10	MRA4003T3OSCT-ND 
TRANSISTOR NPN 50V 0.5A SOT-23	$2.31		7	497-2531-1-ND
10K resistors			$0.88		10	311-10.0KFRCT-ND
470 Ohm resistors		$0.88		10	311-330FRCT-ND
3 pin terminal block 5.08mm	$0.98		1	281-1436-ND
12 pin terminal block 5.08mm	$3.86		1	281-1441-ND
Resonator 4.00MHZ Ceramic w/cap	$0.54		1	X902-ND
relay				$6.00		5	255-1103-ND
28 pin DIP socket		$0.34		1	AE8928
LED T1/2					1	
CAP CER 1.0UF 10V 10% X7R 1206	$2.64		10	490-1800-1-ND

T o t a l:			$31.74

W3bMa5t3r · 05-21-2006, 04:17 PM

sweetness... subscribed

keep us informed. I've no problem soldering, though the board making might get me.. lol but I'm willing to give it a go. That's way cheaper than anything else I've seen.

Rickertsen2 · 05-21-2006, 04:57 PM

Quote: Originally Posted by W3bMa5t3r

sweetness... subscribed

keep us informed. I've no problem soldering, though the board making might get me.. lol but I'm willing to give it a go. That's way cheaper than anything else I've seen.

If there is demand i can probably make a kit with a premade PCB available. I would really like to make a fully assembled product, but i don't know anything about the process.

It turns out, making a board isn't as hard as it sounds. I found a method that is pretty easy. It doesn't look like it should work well, but in actuality works awesome. I found it Here. I will summarize the process.

1.) Print out the pattern onto Inkjet Photo Paper using a Laser printer. If you are like me and don't have a laser printer, then print it out on photo paper(for quality), take it to Office Depot, Kinkos, etc and use their laser copier, to copy the artwork onto the inkjet photo paper. I have tried two different brands of paper, one works better than the other, but both work well.

2.) Prepare the PCB by cleaning it off well. You may want to use some high grit sandpaper like 1000 grit or whatever to get the dirt and oxidation off. Alternately, i had some stainless steel cleaner lying around that brightened it right up on contact. Just for good measure, i went over it with some rubbing alcahol.

3.) Cut out the pattern and iron it on to the board. Use the hottest setting you have along with plenty of pressure, and take your time, The paper will stick to the circuit board and so will the ink. TAKE YOUR TIME. You cannot use too much heat, too much pressure or too much time. This is the most critical step of the process, but it is not hard if you take your time and work the whole thing over thoroughly.

4.)You now have a blank circuit board with a piece of paper stuck to it. Run it under warm water and carefully peel off the paper. This will not happen cleanly and will take some work. using your fingers, a rag or whatever else, remove all fragments of the paper. The ink is fused to the board, but it is not impenatrable. Care must be taken to scratch/pull off all the paper without damaging the ink. Paper left over the ink is ok, but make sure there is none anywhere else.

5.)Now it is time to etch the board. If you have screwed up before this point, you can use some acetone to clean off the entire board and start over. Soak the board in tray of Ferric Chloride (available at many radio shack's) until all the copper except that covered up by the ink is eaten away. DO NOT do this in anything metal. This stuff will screw up anything metal. Do not pour it down your nice stainless sink, it will screw that up too. The etching will take awile. Monitor the process stirring occationally. If you can heat up the solution, the process will go a little quicker. For my board it took about half an hour.

6.) When the board is finished, rinse it off. Use Acetone to clean the ink off leaving you with a nice shiny board.

7.) drill the holes. You will need REALLY small drillbits. I got mine from http://www.store.yahoo.com/drillcity/10pac8503new.html. It says they are for drilling propane orfices, but one the package they say they are for drilling PCBs. You are done.

Scouse Monkey · 05-21-2006, 05:03 PM

keep up the good work. am watching

what code language are you gonna use?

W3bMa5t3r · 05-21-2006, 05:07 PM

Yeah, I saw some of the products at the Rad Shack for doing this, but I wasn't tooo sure I wanted to try it, but you make it sound easy enough. Are you using a single or double sided copper clad board? Does the IC have to be programmed, and if so, will you be doing that as part of providing the kit? Also, what do I print out? One of the pics you have posted above? Thanks :-)

Rickertsen2 · 05-21-2006, 05:27 PM

Quote: Originally Posted by Scouse Monkey

what code language are you gonna use?

The actual PIC chip will be programmed in C. On the computer side, i'm not sure yet. I'm thinking i will provide examples of how to talk to it in C++, VB and maybie JAVA. What do yall want?

Quote: Originally Posted by W3bMa5t3r

Are you using a single or double sided copper clad board?

After much work, i figured out how to do it on a single sided board with only 1 jumper wire. This is the first PCB i have made myself and i was a little weary to try double sided right off the bat as you have to get both sides aligned pretty perfectly. There are through hole parts on the top of the board, and then some surface mount stuff on the bottom.

Quote: Originally Posted by W3bMa5t3r

Does the IC have to be programmed, and if so, will you be doing that as part of providing the kit?

Yes, it does have to be programmed. If i provide a kit, i will program it.

Quote: Originally Posted by W3bMa5t3r

Also, what do I print out? One of the pics you have posted above? Thanks :-)

I'll post another image of what you need to print out once i get everything working which will hopefully be fairly soon.

W3bMa5t3r · 05-21-2006, 05:34 PM

Quote: Originally Posted by Rickertsen2

The actual PIC chip will be programmed in C. On the computer side, i'm not sure yet. I'm thinking i will provide examples of how to talk to it in C++, VB and maybie JAVA. What do yall want?

After much work, i figured out how to do it on a single sided board with only 1 jumper wire. This is the first PCB i have made myself and i was a little weary to try double sided right off the bat as you have to get both sides aligned pretty perfectly. There are through hole parts on the top of the board, and then some surface mount stuff on the bottom.

Yes, it does have to be programmed. If i provide a kit, i will program it.

I'll post another image of what you need to print out once i get everything working which will hopefully be fairly soon.

As far as the programing side goes, I've no clue, so I'm out on that one. Single sided board with only one jumper will work for me. :-) SMT and all are good too. I also don't have a way to program the chip, so if you provided a kit that would be AWESOME!! :-) Just let us know when it's all good to go and thanks

Scouse Monkey · 05-21-2006, 05:59 PM

VB and c++ are perfect for me.

edit: an i know people who can do java so your heading the right way if you do a mix or just one. VB would probably be the most universal though. I would see what the RR and CF people would prefer as getting frontend support would be awesome.

Rickertsen2 · 05-21-2006, 06:00 PM

Here are some pics of the board i made:

The top
http://geargrinders.net/james/usbr/s001.JPG

The bottom
http://geargrinders.net/james/usbr/s002.JPG

kamikaze2112 · 05-22-2006, 12:43 AM

VB would definately be a good thing

W3bMa5t3r · 05-22-2006, 09:15 AM

Quote: Originally Posted by Rickertsen2

Here are some pics of the board i made:

The top
http://geargrinders.net/james/usbr/s001.JPG

The bottom
http://geargrinders.net/james/usbr/s002.JPG

Sweet, that should be easy enough to solder and with the directions you gave for making the board this should work great.

lol I'll just have to rely on the rest of you guys for the software side

I just noticed too, your board/circuit gives the option of normally open or normally closed for the relays. That is sweet, since the few other usb relay boards I've seen are one or the other.

MatrixPC · 05-22-2006, 10:03 AM

Quote: Originally Posted by Rickertsen2

It turns out, making a board isn't as hard as it sounds. I found a method that is pretty easy. It doesn't look like it should work well, but in actuality works awesome. I found it Here. I will summarize the process.

I used that Staples paper and Lazer Toner transfer to build the PCB for the Sproggy PSU.
It came out really clean

davesaudio2 · 05-22-2006, 03:47 PM

Have you calculated the trace widths required for the 15amps?
many board houses also do small production runs.
Microchip also have a small scale pre programming service.

shotgunefx · 05-22-2006, 03:53 PM

Have you looked at http://www.expresspcb.com ?

A good alternative if you don't have the time to learn eagle. It looks like you might be able to fit in on a mini-board. If so, 3 for $51.

I've used their service and was quite happy.

Here's a pic of the rgb led driver boards I made. I had to pack it damn tight though.

Rickertsen2 · 05-22-2006, 06:53 PM

Thanks for you interst everyone.
I got the parts today and assembled them (mostly). The USB connector is lying beside the board, because i routed the traces wrong, and most of the connectors are missing because DigiKey sent me the wrong thing.

Here are some pics:
The top

The bottom with the SMD components.

I tested all the hardware and it seems to work. Time to get programming!

Quote: Originally Posted by davesaudio2

Have you calculated the trace widths required for the 15amps?
many board houses also do small production runs.
Microchip also have a small scale pre programming service.

I did not do the calculations but it is something i am thinking about. As you can see in the pics, the power traces are covered in a thick layer of solder which makes up most of the cross sectional area. If/when it ever goes into or a kit or production, i will fill all the available space. What i really need to know is what kind of volume small kits like this are usually produced in. I figure I would need at least 10 to make a kit for mp3car people worthwile and at least 100-500 to make an assembled product. Relay boards are useful to more than just carputer people.

btw shotgunefx, that RGB driver is pretty sweet. I've been contemplating a similar project.