I changed the title from the thread.
The pump is in-da-house and the first tests are done.
So I really aimed at the cheapest pump that draws 65% of vacuum at 15$ all in price.
Found it on the auction site under:
DC12V 65Kpa DC micro vacuum pump Pumping air pump 65Kpa Air sampling
It seems they increased price to an amazing 16.14$ meanwhile.
In picture attached below it shows to draw more than the promised 65%, it went 78% of vacuum, huray.
It comes with nothing on the poles as in the selling picture, but these little motors like to have some capacitor on the poles, so there's less of sparks forming on the brushes, sparks lead to heat lead to shorter life time or faster degradation of performance. It will no doubt work without, but I like to do things properly if possible for a buck.
Between the poles comes a 470nF 250V capacitor which does most of the job.
On the auction site they come as
4 pc - .47uf 250v (0.47uf, 470nf) NP axial capacitors FREE SHIPPING
Only 4$ all in price.
I did extra effort with 2 capacitors, 1 from each pole to the iron mass of the motor, this is really optional but takes away interference to surrounding.
On the auction site they come as
50pcs Monolithic Ceramic Chip Capacitor 0.047uF 47nF 473 50V
Only 1.42$ all in price.
All these capacitors have no polarity to respect.
Just take care the + from supply comes to the red dotted motor pole.
I had a mimo powder pulp that did not drip 1 drop, unless the pump was started and all liquid came trough wonderfully and clean.
Then I tried powdered rue, but this did not work, and I cannot imagine that even a full vacuum would be sufficient. Some drops came trough but it was to slow to let the motor run so long for it.
Give it 1 minute and it comes to its max vacuum in a 1 liter bottle.
So it worked, but the main question is how long it will keep up performance for that price of pump. We'll see. It makes a soft grumble sound, no high pitched RPM wining, thank god
Now as power supply: I used a heavy 12 V DC station for testing, but reason I choose for the 7Watt pump was to find a cheap supply too. I was hoping something convenient like this would work, but I have to test that later:
AC 100-240V To DC 12V 2A Adapter Plug Power Supply For 5050 3528 Strip LED
5$ all in price.
So that a total price of below 25$ adapter + pump was reachable.
Another advantage, this combo fits almost in your pocket.
And what if it keeps doing the job well for once a run in a month?