PROJECT FILES:
For the PANEL METER circuit you will want to visit my blog page regarding that little project.
First, I would like to recommend taking the time to view Dave's video on his Constant Current Dummy load. HERE This video gives quite an awesome explanation of the circuit.
I started by choosing components out of my "leftovers" bin. The thought process I had behind the component selection was to use anything I had lying around to build it. Personally, I didn't purchase any parts specifically for the project (other than the panel meter). If you are looking at my BOM (Bill of Materials) HERE , keep in mind these are parts that I had sourced that may be similar to what I actually used... rather than exact.
After laying down the schematic and processing my board lay out, I used an LPKF milling machine to carve out my PCB.
As I had mentioned, this enclosure required extensive modification to be useful in this case. Much of the little ribs and do-dads on the inside of the case had to be cut off. This plastic is quite soft, so a single edge razor blade did the trick. Vent holes needed to be drilled in the top for the fan. The design is such that it pulls air from the back vent, across the heat-sink, and out the top. The pot is physically too long (again, this is all I had laying around) so I needed to cut a large hole out of the front panel to accommodate the body of the Pot. (instead of just the shaft as you would do normally.)
NOTE: The pot in the BOM is a shorter one and should fit better.
The panel meter was connected in and mounted. More on the Panel Meter HERE.
And then we are set. (I hope) Apply 12 Volts DC to the supply jack. Connect a DC power supply to the input. Adjust the pot to the desired current load and Bob I suppose is your uncle.
I hope you have enjoyed this small write up. If you like what you see, share it, comment below. Comment if you didn't like it. I am totally open to suggestions and constructive criticism.
Thanks!
-Richard
I started by choosing components out of my "leftovers" bin. The thought process I had behind the component selection was to use anything I had lying around to build it. Personally, I didn't purchase any parts specifically for the project (other than the panel meter). If you are looking at my BOM (Bill of Materials) HERE , keep in mind these are parts that I had sourced that may be similar to what I actually used... rather than exact.
After laying down the schematic and processing my board lay out, I used an LPKF milling machine to carve out my PCB.
Population of the PCB was rather straight forward. With few exceptions... First I had to modify my heat-sink quite extensively to provide clearance for the two Banana type connectors on the rear panel. (shown later) Second, to minimize the footprint of the components I chose a stacking arrangement got the 10Ohm resistors (10X 10Ohm in Parallel = 1Ohm). Lastly, I decided at last minute to add a fan to the heat-sink This is due to the confined space in the enclosure I have for this project.. I thought it would be wise to forcefully exhaust the heat from the case. Sooo.... I soldered the fan to the power input jack.
NOTE: A word about the fan... it ran too fast and was far to noisy. So I had to add resistance in series with the fan to slow it somewhat.
It ended up looking something like this:
Next steps... fit it into the enclosure I have. I have specified in the BOM a HAMMOND 1598ASGY enclosure for this project, but it is a bit tight and requires quite a bit of modification to work here. I used this enclosure because I have a few of them laying around. You might want to look at something a bit bigger if you plan on building this as I have laid out here.
Let's begin to squeeze this circuit into this case:
The convenient part about these HAMMOND cases are that it is a clam shell design, with removable end plate. This makes whatever you put into them very accessible. Custom end plates are easy to design as well. Again with my LPKF machine I milled out some end plates for my case. The Gerber files for the end plates can be found HERE. The material used to make the end panels is something called Gravel-Ply II. They slip nicely into the slots on the ends of the clam shell. After milling I added all of the accessories needed to interface with the outside world. The Banana connectors, switch, pot, panel meter.
Once I had these panels complete I wired them appropriately as stated in the schematic. NOTE: my wiring in the picture is a mess... I cleaned it up considerably in the end.
NOTE: The pot in the BOM is a shorter one and should fit better.
The panel meter was connected in and mounted. More on the Panel Meter HERE.
And then we are set. (I hope) Apply 12 Volts DC to the supply jack. Connect a DC power supply to the input. Adjust the pot to the desired current load and Bob I suppose is your uncle.
I hope you have enjoyed this small write up. If you like what you see, share it, comment below. Comment if you didn't like it. I am totally open to suggestions and constructive criticism.
Thanks!
-Richard
No comments:
Post a Comment