Hi, this is Wayne again with a topic “Projects with Ryan Slaugh: Building a Mobile Prototyping Platform”.
Having your own shop is great, but sometimes all you have is the kitchen table regardless. You still need a place where you can write. Your code lay out your tools for use and your parts and work on your electronics. This often happens to me, so i built the mobile prototyping platform and i’m going to show you how i did it. The mobile prototyping kit involves a dell mini10v for control and data acquisition and the hardware is housed in a pelican case. I have dc voltage outputs from a computer power supply, a radio shack dmm, that’s rs-232 connected breadboard field and digital. I o provided by an arduino uno, that’s reprogrammable to any input and output configuration.
I need. The prototyping kit has plenty of features: for instance, the front pocket to carry your jumper wires, always need plenty of jumper wires, even more jumper wires over here, two breadboard areas are smaller and larger, giving plenty of prototyping room a breakout, screw type terminal from the arduino Uno, giving i o and two dc voltage lines from the computer power supply. This gives plus minus 12 volts 3.3 5 volts and plenty of ground plugs on the back cover. There’S the dmm connected to the hub through a usb to rs232 converter.
This signal comes into the hub and then connects to the main line going to the dell mini 10v also into the hub are two different connector types of usb, so i can connect to an arduino leonardo if i wish, or other arduino platforms or even other usb Platforms as needed, the best way to show you how something’s put together is take it apart. First, that comes off. Is the dmm pull it off from its cable? There dmm actually just velcros to the back of the case, so you can remove it for easy use away from the case out in the field measuring whatever else you need to measure. The dmm connects to the system through a custom umbilical that connects into its rs-232 and delivers power for the communications and then into the usb hub.
The actual platform where all the electronics are mounted is a polycarbonate base that can be easily pulled out. It actually velcros to the bottom of the case. I know what you’re thinking velcro isn’t strong enough trust me. The velcro i used is and i’ll show you a moment. The power supply can be unconnected using a quick, quick disconnect and that allows you to actually change. Electronics or fix anything very easily for projects.
Sometimes you choose the case and sometimes the case chooses you in this case. The 1450 was what i had on hand for this project. So i designed everything to build and fit inside, as mentioned before, the velcro used is the industrial strength type. In fact, when i first started doing this project, i had the velcro adhesive, giving way before the velcro did so.
I had to jb weld the velcro down to the bottom of the cases this ensured that it actually worked and wouldn’t rip off the adhesive to bring power in. I use a regular power tail or end of a cord connected to a receptacle. That’S a panel mount receptacle.
These are easily locatable at digi-key. They have a fuse built in for safety to mount it in the box. I use a drill to start the hole and then a dremel to actually etch out the shape that i needed.
I then drilled holes in each side for the mounting bolts, slid it through the case and bolted it in. I connected the power tail using regular wire spades. The electronics is mounted inside a polycarbonate or polycarb frame that sits inside the pelican case.
I like polycarbonate, better over acrylic, because acrylic can crack and shatter and it’s kind of a mess to deal with bending it requires heat, etc. Polycarb doesn’t you can drill it easily, cut it easily and it’ll actually bend just like some soft metals without heat needed? So i made a nice compact case in order to fit inside the pelican after bending my polycarb into shape and affixing the velcro tabs onto the bottom. I added a stabilizer in the center just to give a little more rigidity and allow for stability in the center of the box. In case you were pushing or pulling things on top of the breadboard or into the power terminals to lay out the power terminals. I lay out two columns with tape and marked exactly the measurements that i needed and then drilled the holes required for the power terminals to be screwed in after that i actually installed the terminals themselves, color coding for different power rails and different options. Green for ground orange for 3.3, black for 5 volt white for plus 12 and purple 4 minus 12 volts all of the components mount to the polycarbonate shell in one of two ways: either they’re bolted on or they use adhesive. The dc terminals, as we’ve seen before, have their own bolt and their own nut that secures them to the polycarbonate top the arduino uno mounts underneath with its own bolt pattern and i’ve also added a hole here.
So i can access the reset button. The usb hub mounts to the surface by using double-sided sticky tape, as does the breadboard surfaces, the breakout bar actually bolts and has a hole that goes through and then can be wired to the arduino. The power supply mounts in two locations front and back this back location here allows for a piece of metal to slide into the chassis of the power supply itself right here at the back and then be bolted to the polycarb. The front has a little t-nut.
That goes into the power supply case as well. Both these tighten down give a good, stable platform on which the power supply is mounted. The power supply is wired to the terminals via the atx connector that came with the power supply. That way, it gives a quick disconnect in case you need to swap the power supply out.
For any reason, if you look at the atx, connector you’ll see a resistor. This is to give the power supply a constant load. Most computer power supplies will not turn on their outputs unless a load is sensed so adding this resistor, giving it a load to sense, allowed the power supply to turn on its outputs whenever main is attached. Another option for this power supply is to mount a switch here.
That would turn the resistor in and out of the circuit, so you could turn off the power supply if needed. The way i found the proper resistance value is, i found the current sense lines and just change the resistance until i found a good, stable resistor that would allow the power supply to turn on every time. Mains power was applied, all of the analog inputs and digital. I o have wires soldered onto them and they are connected to this breakout terminal block.
This terminal block has all the signals available, plus 5 volts, 3.3 volts ground digital. I o and analog inputs. I can take a jumper wire hook it to there and jump it right into the breadboard you’ll note on this connector to the meter that there’s more than just the rs-232 to usb hub connection, there’s actually power wires. This old meter required plus and minus 12 volts and able to activate the communication circuits on the meter itself.
New meters now have usb ir or even bluetooth for connection this project was born out of necessity. I needed a mobile prototyping platform so looking around, i found that i had this case with some simple fabrication. I was able to build a box mount it to the case using industrial strength, velcro and use an optiplex power supply, found off ebay, using some simple power tools and some wiring techniques. I was able to put all the parts i needed in place in order to have a workable solution to my need along the way of designing and building this, i thought of a lot of changes that could be made for a rev2.
In fact, i’ll probably put in a larger power supply an adjustable power supply even and i might include a dso nano like you find on the maker shed well. I hope that my ideas give you ideas for your own mobile prototyping kit, happy building, .