The motor in the submersible pump I was using has started to rusting after a year and a few months. The rust stops the motor from spinning until I hit it with a high enough voltage which eventually exceeded the power supply I was using.
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| Pump motor is rusting |
I ordered a couple of replacement pumps, but they are probably stopped somewhere between China and the post office due to the virus. I have decided to go for a different approach.
I made a servo controlled valve to control the water flow from a
siphon. This simplifies the overall design by removing the pump at the source and reduced the wring needed.
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| Top view of assembly |
I used a
Tower S9 micro servo mounted in a cut out dental floss case with a couple of M2 screws. I used a cheap
metal air valve, but it seems to work okay so far for water. It is held down with 3 L shaped bracket with a couple of screws. The brackets are made out of the left over bits from the case. The servo arm is coupled to the handle with a 'g' shaped metal strip from a transformer. The valve side is loose enough to allowed it to move to accommodate for minor misalignment.
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| Side view of the assembly |
Two large holes are drill on the side of the case for connecting the tubing.
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| Timer Aux power supply |
There are a few modifications needed on my
timer project for driving the servo.
- R2 is replaced by 2.7K while R7 is replaced by 8.2K. This sets the output to 5V
- D3 is removed. The 5V output on J4B is now always on.
- J6 is installed. The /EN signal is used for driving the servo
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| /EN (PD3) is used as PWM for driving the servo |
The 5V, GND, PWM signal are routed to a 3-pin connector for the servo.
I used TIM2 for generating a 50Hz PWM signal for controlling the servo. TIM2 is disabled after 1 second when the servo is in the "Off" position. This powers down the servo and prevents the annoying rattling in some cheap servos.
