Electric Pump

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for delivering precise doses of Saline

Whilst dismantling an old inkjet printer I discovered a small pump that had been used to circulate ink to a local tank near the print head. I salvaged this pump and some of the fine bore tubing in the hope that I could work out how to power the device from a simple electronic circuit and battery.

My intention is to either use pushbuttons to deliver say 1 microlitre or 2 or 3... Or to dial up a dose on thumb wheel switches such that a single button delivers a measured dose.


The printer was a "Brother type HJ-770" and the pump is a diaphragm type operated by an armature that is in turn activated by a coil that connects to the two tabs.

The picture is 2.77 x full size. I have no idea of the rated voltage, but I will start my experiments at 5v and work up from there using water as a test medium.

One thing confuses me at the moment and that is a lack of obvious valves on either the inlet or outlet of the pump, nor can I find any valves in any other parts of the original plumbing. The only conclusion I have reached so far is that the inlet is radial to the circular diaphragm chamber and the outlet is at a tangent to this circular wall. Perhaps there is some subtle fluidic process that causes one way flow.