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View Full Version : My first time designing a circuit and circuit board.



Jimbo30
04-16-2010, 11:38 AM
Below are a couple pictures of the circuit I will be using for my project.· BS2p-40, MAX485 IC, two ADC0831, reed relay and some other stuff.· I must say it was a challenge and learning experience all at the same time.· The only issue I ran into was the H-bridge circuits I bought only allow 2-amps per channel so I had to order better h-bridge boards that can handle more amps.

PJ Allen
04-16-2010, 11:59 AM
It's certainly uncluttered.· Did you etch it yourself?· [Could've worked in an 'on' LED easily (Ooo, Aaah, LED.)]

How're you using all this then?

Jimbo30
04-16-2010, 12:17 PM
PJAllen

I was going to try etching it at the Tech college I went to, but I figured there would be less headaches if I just used a PCB design software and have the board manufactured. As for it being uncluttered, I was nervous when designing it, lol. This board is the control system for the ROV I am building. The only thing I have left to do is the motor control. I have the motors communicating, but my H-bridge boards go into thermal overload after a few minutes of operation. I am new to robot building so it is a learning experience as I go.

Post Edited (Jimbo30) : 4/16/2010 4:23:19 AM GMT

WBA Consulting
04-16-2010, 01:38 PM
You need to start over, it's way too clean and organized!

Very nice job, good layout. Things where they should be. Nice job making your leftover I/O pins accessible. I think that should always be done for any design.

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Andrew Williams
WBA Consulting
WBA-TH1M Sensirion SHT11 Module (http://www.aestheticacoustics.com/sht11_01.htm)
Special Olympics Polar Bear Plunge, Mar 20, 2010 (http://www.kintera.org/faf/donorReg/donorPledge.asp?ievent=322002&lis=1&kntae322002=BDAEE98623FB443591C072E356710D6B&supId=265642883)

Jimbo30
04-16-2010, 10:15 PM
Thanks WBAconsulting!· It really means a lot coming from a professional.· One thing I am disappointed in is overlooking·how I have the·PWM channels set up.· I have them right next to each other and what I should have done was have it so the three wire extension cables would fit nicely side by side for the H-bridge boards.· Good thing they sell one wire extensions.·

Leon
04-17-2010, 05:15 AM
I would have mitred those right-angled corners, they don't look right. Supply and ground tracks could be wider, and you don't seem to have any decoupling capacitors.

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Leon Heller
Amateur radio callsign: G1HSM

Post Edited (Leon) : 4/16/2010 9:22:15 PM GMT

Jimbo30
04-17-2010, 05:25 AM
Decoupling you mean filtering caps right?· My measurements didn't seem to be jumping around too much so I didn't add them.· Do you think I should have added a couple caps by the 7812 for the lights?·· Also, what is a general rule of thumb for the traces when dealing with ground and power?




Leon said...
I would have mitred those right-angled corners, they don't look right. Supply and ground tracks could be wider, and you don't seem to have any decoupling capacitors.

PJ Allen
04-17-2010, 09:05 AM
Having all that exposed copper will make the modifications a lot easier, too.

oh,... :)

Leon
04-17-2010, 06:57 PM
I meant decoupling capacitors for the MAX485 and ADC0831s. They should have one each, ideally. I'd have made the supply and ground tracks 50 mil wide.

Do you have a diode across the relay coil?

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Leon Heller
Amateur radio callsign: G1HSM

Jimbo30
04-17-2010, 11:47 PM
The Diode I have.· I am still learning so I had no idea about decoupling using caps, but everything is operating just as tested other than my PWM channels on pin 21 and 22 of the BS2p-40.· ·
On my PWM channels, I am now stuck on trying to get the right combination of a resistor and capacitor for charge time so I can·set the speed of my motor correctly.··What seems to work well for one motor doesn't necessarily work for another motor· ·.··· I used a small 5V motor (without a load)·for testing and now that I am trying to get the 12V motor with a muffin fan on it everything is quite different due to the load I have on the motor.· I like the challenge though!· Do you have any suggestions??????






Leon said...
I meant decoupling capacitors for the MAX485 and ADC0831s. They should have one each, ideally. I'd have made the supply and ground tracks 50 mil wide.

Do you have a diode across the relay coil?