Uni-Byte 0228 - Let's Build A VARIABLE DC Load: (It LIVES) Part 2
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- เผยแพร่เมื่อ 21 พ.ย. 2024
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In this multi-part series we are going to design and build a variable DC load. In part 2 here we will build up the main board and do some initial set-up, adjust the program for proper fan operation and do some functional tests. In subsequent videos we'll do more set-up, test it's limits and finally put in a nice cabinet.
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Nice Job! It turned out well Uni.I really like the heatsink you used. It's like it was made for this.
RJ
Thanks RJ. Actually, in a way this was made for the heatsink.
So pleased it lives, Everything working, boards and all. DC loads can be surprisingly tricky. I bet that's a load off your mind.
I see what you did there :)
LOL! Thanks, it is!
Have you ever used the ATtiny 85 microcontroller?
Yes, but it was more than 12 years ago now. I still have a pile of them around but really don't do a lot of MCU work anymore and if I do (like here) I usually use a PICAXE (I have even more of them!)
Awesome ! I would like a look at the code and perhaps a walk thru (pretty please) at some point. What a great start and now the next fun part is characterizing it and zipping it into a box ! Oh My that meter would drive me nuts :)
Add another vote for "a look at the code and perhaps a walk thru (pretty please) at some point."
@@cougar1861 :)
I'll see if I can fit it in. It is really simple code.
@@uni-byte :)
i think you should remove the tape over the heatsink, it is creating a duct which you want when you want to route air, but in this case you dont want to route the air, what you want is maximum airflow over the heatsink fins. in current setup airflow is limited by what the first fan can suck and also constrained by its body as the second fan cannot pull more air than what the first fan is providing. removing the tape will allow the second fan to suck more air from the surrounding and therefore more airflow on the heatsink. you can test this
I would like to see that test too !
Taping the cavity shut promotes more laminar flow and hence less resistance due to turbulence. Opening it up should cause turbulence and actually reduce the airflow. I can try it in the next video to see what happens.
fans do not blow directed air perpendicular to motor axle, instead they push it outwards diagonally in all directions. It concentrates all air pressure near the blades with very little flow reaching any meaningful distance away from fan's plane. Air flow has to be focused and this channel is designed for that.
Heatsink like that is probably meant to be put with a cutout to PCB, which also makes sense in terms of material and weight optimizations.
@@Mr.Leeroy Good point. Yes, a non-boxed (open blade) fan does does push air out like you say. However these are box fans. 50% of their depth is after the fan blade and amounts to an exit duct duct which will reduce the effect you're talking about by a little a bit. Your guess as to how it is designed to mount is probably correct. I chose this way for easier access to the mounting hardware but I guess I could have used self tapping screws.
@@uni-byte No, I'm talking about this type of fan you have in the video. They really are that inefficient; shroud around the blades is too short to be effective without direct contact to other means of flow direction control (usually heatsink fins).
Do you have a source and/or model number for these tunnel heatsinks?
My search-foo failed when I attemped to find something like this on CN marketplaces.
In video #0209 (MAILBAG #28) you will find a link to it in the description. YT will not let me place external links in the comments section.
@@uni-byte found it. Many thanks.