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Some interest was offered, so here's a quick guide on how to build your own fan that reverses direction at intervals so it seems to breathe in and out. This is the bare bones of what COULD be done, and the expense is unfortunate because the components mainly have to be bought in bulk. Anyone interested in working with me (I'll buy parts and design what the customer wants, you build it since I have terrible co-ordination and fine motor control) PM me or comment or what have you and we can work something out.
Category Story / Miscellaneous
Species Unspecified / Any
Size 50 x 50px
File Size 91.4 kB
The idea is interesting, but i see a few flaws there.
The major problem is the fan. Except for handheld plastic toys, there are since at least ten years only electronic commutated fans in use that can run only in one direction by their design. There is no way to reverse them unless you completely redesign the motor and drive electronics.
What you can do is to place two fans back to back and alternate between them. You should leave at least one cm gap between them or you might get an very noticeable tone from the closely passing blades.
Also i would recommand an stronger driving circuit. Most operational amplifiers are designed for much smaller currents and cant handle such an motor well. My suggestion is the classic NE555 that can safely handle 100mA, or the dual type NE556 for two fans.
The major problem is the fan. Except for handheld plastic toys, there are since at least ten years only electronic commutated fans in use that can run only in one direction by their design. There is no way to reverse them unless you completely redesign the motor and drive electronics.
What you can do is to place two fans back to back and alternate between them. You should leave at least one cm gap between them or you might get an very noticeable tone from the closely passing blades.
Also i would recommand an stronger driving circuit. Most operational amplifiers are designed for much smaller currents and cant handle such an motor well. My suggestion is the classic NE555 that can safely handle 100mA, or the dual type NE556 for two fans.
Oddly enough, as I mentioned by quadsuit fan can run backwards. Actually, both the 50mm and 40mm can do so. I must have gotten lucky.
Smaller case fans don't take much current. My op-amp wasn't heating up running it, but I'll take your word for that.
How would you run two fans like that? I thought maybe have the other fan have its live on the low and ground on the virtual ground, but it seems like that would put a lot of stress on the batteries by forcing them to reverse direction when the fan does.
Smaller case fans don't take much current. My op-amp wasn't heating up running it, but I'll take your word for that.
How would you run two fans like that? I thought maybe have the other fan have its live on the low and ground on the virtual ground, but it seems like that would put a lot of stress on the batteries by forcing them to reverse direction when the fan does.
First of all, can you please tell me the maker and type numbers of your fans that can actually reverse? I am very interested to see them because all small fans that i know since years have the cheap brushless type of motors that cant be reversed.
My suggestion for an circuit that can work with both types would be an bridge circuit that is fed from something like an fourpack of AA cells (preferably the rechargeable NiMH type).
The circuit would alternatingly put one of the outputs to positive, then rest with both at negative, then the other output positive, then resting again and so on.
If two fans mounted in opposite directions are useed they are connected from each output to negative. Then alternatingly one fan runs, both fans stop, then the other fan runs...
If one reversible fan is used it is connected between both outputs. Then it gets alternatively positive on one wire and runs in one direction, then stops because negative on both wires, then runs in reverse with positive on the other wire...
My suggestion for an circuit that can work with both types would be an bridge circuit that is fed from something like an fourpack of AA cells (preferably the rechargeable NiMH type).
The circuit would alternatingly put one of the outputs to positive, then rest with both at negative, then the other output positive, then resting again and so on.
If two fans mounted in opposite directions are useed they are connected from each output to negative. Then alternatingly one fan runs, both fans stop, then the other fan runs...
If one reversible fan is used it is connected between both outputs. Then it gets alternatively positive on one wire and runs in one direction, then stops because negative on both wires, then runs in reverse with positive on the other wire...
http://www.amazon.com/gp/product/B0.....UTF8&psc=1 and http://www.amazon.com/gp/product/B0.....UTF8&psc=1
A 4-pack could work if you have the holder for it. A little bulkier than 2 9Vs I think.
So logic gates? Easier to reprogram.
I was going for the smallest circuit possible with as few connections. A more complicated circuit has benefits. I was going for simplicity in this case. If there's demand I could do something more ambitious, but only if people take an interest. One day I intend to buy a simple surface ECG and experiment with a brain controlled tail.
A 4-pack could work if you have the holder for it. A little bulkier than 2 9Vs I think.
So logic gates? Easier to reprogram.
I was going for the smallest circuit possible with as few connections. A more complicated circuit has benefits. I was going for simplicity in this case. If there's demand I could do something more ambitious, but only if people take an interest. One day I intend to buy a simple surface ECG and experiment with a brain controlled tail.
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