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Build a circuit board

Posted: Mon May 02, 2016 6:50 pm
by agraco
Hi. I am building my first circuit board ...

Project: I would like the RPi to control 5 LED strips, plus 1-2 motion sensors. Each LED strip needs 3 MOSFETs, which means 15 GPIO pins, plus 2 sensors.

Progress so far: Using a breadboard, I have prototyped one of the LED strips with the MOSFETs. I used thermostat wire so that the RPi stays in a central location, but the LED strip is in the room of one of my children.

Challenge: I would like to graduate from a breadboard to a circuit board. I can see myself needing a lot of room on the circuit board so I don't quite know how to get organized.

(1) Is a ribbon cable, connected to a T-Cobbler, and then soldered to a circuit board the only way to join the RPi to the circuit board? I get that using jumper cable is a no-go and that I need a more permanent solution.

(2) Is the T-Cobbler soldered onto the circuit board?

thanks for any tips...

Re: Build a circuit board

Posted: Mon May 02, 2016 7:01 pm
by Douglas6
A cobbler will take up quite a bit of space on the circuit board. I would use female dupont cables with the other end cut and stripped and soldered to the board. Or solder just as much header as you need to the board and leave the cables intact.

Re: Build a circuit board

Posted: Mon May 02, 2016 7:09 pm
by agraco
Thank you. my thinking on the female dupont cables is that they are useful for prototyping...Then don't seem to firmly stay on the RPi. And since I will be using 17 GPIO pins, that is a lot of cables to play with.

I have not found a ribbon cable that is male-female and can be pushed into a circuit board. . :/

Re: Build a circuit board

Posted: Mon May 02, 2016 8:54 pm
by mthomason
If you want to go with a ribbon cable, just solder one of these to the circuit board to plug the other end of the cable into.

https://www.coolcomponents.co.uk/raspbe ... Gwode3kAZg

Re: Build a circuit board

Posted: Mon May 02, 2016 11:07 pm
by mikronauts
Once you have your circuit fully working on breadboards, transfer it to a permanent prototyping board.

Here are a couple of examples:

http://www.mikronauts.com/raspberry-pi/ezaspi/ (can stack on a Pi with 26 pin stacking connector)

http://www.mikronauts.com/proto/ezaspieproto300/ (can stack on a Pi with a 40 pin stacking connector)
agraco wrote:Hi. I am building my first circuit board ...

Project: I would like the RPi to control 5 LED strips, plus 1-2 motion sensors. Each LED strip needs 3 MOSFETs, which means 15 GPIO pins, plus 2 sensors.

Progress so far: Using a breadboard, I have prototyped one of the LED strips with the MOSFETs. I used thermostat wire so that the RPi stays in a central location, but the LED strip is in the room of one of my children.

Challenge: I would like to graduate from a breadboard to a circuit board. I can see myself needing a lot of room on the circuit board so I don't quite know how to get organized.

(1) Is a ribbon cable, connected to a T-Cobbler, and then soldered to a circuit board the only way to join the RPi to the circuit board? I get that using jumper cable is a no-go and that I need a more permanent solution.

(2) Is the T-Cobbler soldered onto the circuit board?

thanks for any tips...

Re: Build a circuit board

Posted: Tue May 03, 2016 12:02 am
by exartemarte
I had a similar construction issue with an Rpi internet radio project. I made up a short ribbon cable with an idc connector at one to connect to the Pi; at the other end I separated out the connectors and soldered them individually to the appropriate points on the circuit board. Unused connectors were just cut off short. You can use any kind of ribbon cable, but if you use the rainbow coloured type the colours make it easier to avoid wiring mistakes. The idc connector makes a secure connection to the Pi.

Re: Build a circuit board

Posted: Tue May 03, 2016 1:15 am
by asandford
If you control the mosfets via an MCP23017 i2c gpio expander, you only need a few connections (and you can connect up to 8 to the Pi for a total of 128 i/o).

Re: Build a circuit board

Posted: Tue May 03, 2016 2:28 am
by agraco
asandford wrote:If you control the mosfets via an MCP23017 i2c gpio expander, you only need a few connections (and you can connect up to 8 to the Pi for a total of 128 i/o).
Hi. This looks incredibly interesting but, for right now, beyond my skills. I have never built my own circuit board so just getting this to work will be an accomplishment. To give you a sense of where I am:

(1) YouTube is teaching me how to solder a circuit board. :D
(2) I still need to buy a decent soldering iron. :)

Re: Build a circuit board

Posted: Wed May 04, 2016 1:46 am
by asandford
agraco wrote: Hi. This looks incredibly interesting but, for right now, beyond my skills. I have never built my own circuit board so just getting this to work will be an accomplishment. To give you a sense of where I am:

(1) YouTube is teaching me how to solder a circuit board. :D
(2) I still need to buy a decent soldering iron. :)
The chip is quite cheap and readily available in breadboard DIL packages.

Re: Build a circuit board

Posted: Wed May 04, 2016 8:20 am
by norahvoss
I think you can get a lot of useful things on this website if you are a beginner. It's also useful for electronic engineers.
http://hardware.ui3g.com/

Re: Build a circuit board

Posted: Fri May 06, 2016 2:30 pm
by BMS Doug
agraco wrote:
asandford wrote:If you control the mosfets via an MCP23017 i2c gpio expander, you only need a few connections (and you can connect up to 8 to the Pi for a total of 128 i/o).
Hi. This looks incredibly interesting but, for right now, beyond my skills. I have never built my own circuit board so just getting this to work will be an accomplishment. To give you a sense of where I am:

(1) YouTube is teaching me how to solder a circuit board. :D
(2) I still need to buy a decent soldering iron. :)
The MCP 23017 is available in an easy to assemble expansion board called the Slice of PI/O, very easy even for a beginner.

Re: Build a circuit board

Posted: Fri May 06, 2016 3:53 pm
by DougieLawson
I'll second that - I built a project this week. The only hard part was soldering the addressing pads. With hind sight I'd do those first before the IC socket.