The day has finally arrived, I've begun! Hopefully, someone can use these pages to learn about robotics while I'm learning, then making their own bot and making it better! Here we go!
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| A lot of parts to go on that little board! |
First, lets work on the power conditioning circuit. I've spent most of Saturday putting this little thing together. I have the start of the drawing on Post #2, I pretty much stuck to that initial drawing and built the circuit on the Radio Shack prototyping board.
Here you can see all of the parts I have to try and squeeze on this little prototyping board. Initially I was thinking I would be able to break that prototyping board in half and use it for other parts, but that dream died when I saw the size of those 4700uF caps! The 100mH RF Choke was also bigger than I anticipated, I was pretty lucky to squeeze all of these components on the full size prototype board as it was!
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| Problem 1.... header does't fit |
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| problem solved |
Well, lets begin. First up, first problem. The holes on the board don't fit my screw terminals . I wanted to to make it as plug and play as possible, so I thought these terminals would be useful.... Out comes the drill bit to make the holes bigger and make them fit! (note, I lost my drill bit, How could I lose it after I just used it? ugh).
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| Parts Laid Out |
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| Start Soldering |
Now that this problem is solved (just a minor one), time to start locating the pieces parts and see if I can make things fit. After some experimenting (OK, a lot of experimenting), I figured out a combination of locations that keep my mounting holes free and fit everything on. On the right you can see how I finally got everything to fit, on the left, the work to solder them in.
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| Finished Power Conditioner |
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| Power Conditioner Soldering |
Wherever possible, I used the leads of the each component and bent them down to touch the next component using the leads as my copper traces, so to speak. I had to add a jumper wire or two in order to get things completely hooked up, but overall, pretty easy. Just be patient with your soldering, keep a clean soldering tip (I just used a folded/wet paper towel) and don't spend too much time on each point, just touch, solder and back off. The black line in the picture above left is just me tracing my ground around the board to make sure I didn't solder it to the hot and avoid a disaster.
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| Power Conditioner is holding a charge! |
Now, how to test this thing? Putting an ohmmeter across the + and - isn't going to do any good. All of these capacitors are just going to draw all the current out of your meter and make it look like a shorted circuit. So, what to do.... Well, I took a risk. I got out the battery I, tied some wires onto the + and - and then touched them to + and - on my little board. I got a spark the first time (the Capacitors needed charging), but the second time, no spark. That is a good sign. If everything is as it should be, the board should hold charge for quite some time. Lets see.... yep! I'm done for today! It's been a long Saturday so far :).
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| Day 2, Still 10V! |
Sunday, a new day. Today I just wanted to make sure my little creation from yesterday is still good. Putting the voltmeter on, sure enough, I still have charge from yesterday. After about 24 hours my little board has lost only 2 volts! OK, I 'm thinking this board is good to go. Now, on to the next.
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| Add Caps to your Motors |
Another source of noise in any device with motors, is, well, the motors! It is best to get capacitors down as near the motor as you can, trap the noise at the source. My motors have plastic covers on the back so have no idea if they came with caps or not. Opening them up, no, they don't. So, adding them to each motor. Take off the back, solder on a cap so that it doesn't interfere with the cover, put the cover back on and test. done. I didn't grab a pic with the caps soldered on, but you can see it laying there. I used some wire insulation around the leads so they don't short out with the motor case when the plastic cover is put back on, but other than that, no biggy here.
Now to begin mounting the power peripherals, the switches to turn on main power, to disconnect the motors with another switch and the power jack so we can charge our little creation. I arbitrarily chose the left hand side of the robot, just seemed natural. I took off the side, measured things out, placed my fuses with two sided tape and tapped a hole for a screw in the middle.
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| Early Power Control Panel |
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| Power Control Panel (inside) |
On the left here, you can see I've already mounted my fuse holders (one for charging, one for the main circuit). Once those are on, I was able to measure and drill holes for my motor switch, main switch and power jack. On the right, the two fuse holders are at the bottom, the main switch is on the left and the motor switch is on the right.
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| Inside of Power Control Side Panel |
Next, have to wire things up. This next pic shows how I pull a lead from the one of the fuses (the other side goes to the battery) to one throw of the switch, the center pole goes out to the power conditioner circuit I built above (the red wire coming off the center of the switch). Notice also the 2 resistors wired in parallel from the opposite throw to ground. This will drain the capacitors through 205 ohms to ground when the main switch is in the OFF position. The power jack is in the middle, I pulled the + (center) from and ran it to one end of the other fuse. This fuse will be the charging fuse to the battery. In case anything goes wrong, this fuse should save our battery/charger. On the right, I pulled 2 red wires off a throw and pole of that motor switch. One wire will come from my power conditioner circuit, the other will go to V+ of the motor circuit.
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| Outside of Power Control Panel |
After drilling, tapping, mounting and soldering, here is the finished product for the side panel. Also, just to keep my documentation up to date, I've updated my schematic to better match the as built. Some experimenting showed that 5K resistor was too high to drain the caps very fast, so I lowered it to 205 ohms and that seems do draw down the caps a lot faster.
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| Creeper Bot Schematic Rev 2 |
All done with my Sunday.. just have to write my blog entry :). Please note, this will take more time than you plan for it to take! Especially if this is your first robot build. You end up going to stores looking for parts alot. You get some parts, don't like them, get other parts... You really don't know what you want until you try it out. My intention is to record my learning curve here so that if you want to undertake this project, you can follow my pics and posts and get some better ideas for your build. Enjoy! :)
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