I am currently using a pump
Brand : Keyukang
Model : KYK50BPM
DC12V
My power supply has OUTPUT 12V - 1A.
The situation:
When I turn on the power supply, and measure them with multimeter, i get a stable voltage at around 12.41V
But when i connect with the Air Pump alone and measures the voltage with multimeter, the voltage fluctuate greatly from 11V to 1V at the pace of around 1 change per second. The funny thing is when i switch the multimeter positive and negative pin towards the circuit, i get a stable -10V reading. Which is beyond my comprehension.
Your help is greatly appreciated, Pls feel free to ask if you want to know more, thanks!!
It is also beyond my comprehension, but I get a "led power supply" feeling.
I think that the pump is okay, but I'm not sure about the power supply and your multimeter.
I think that the pump is 12V, 400mA or 900mA. The power supply should be more than 1A.
Which power supply and which multimeter do you have ?
If you bought a power supply for leds, then you need a better supply. If you bought a cheap power supply with no certifications from AliExpress/Amazon/Ebay, then the 1A is exaggerated and it might be very noisy. What else do you have that can give 12V ?
Some power supplies are very bad quality. Maybe ten times worse than you think is possible
Q:
May i know what you mean by "LED power supply", isit different from the normal power supply?
Do you mean the minimum ampere to make the motor work is 400mA and 900mA? Or isit refering to the range? If 900mA is the maximum, then could it be over supplying of current to the motor that causes the fluctuation?
The brand for my power supply is sanzhixiaoyu
The brand for my multimeter is Rolson 27259
You may need to get a proper power supply. The supply (and motor driver) must be able to safely handle the stall current of the motor. The stall current is drawn, briefly, every time the motor starts. The stall current can be 10 times (or more) the running current. The stall current should be listed on the motor data sheet. That means that a 1A supply may not be good for a 400mA motor and not at all good for a 900mA motor.v
That is the cheapest possible multimeter there is ! (and I bought one out of curiosity).
The wires of the leads break easily. Can you check that ?
It can measure voltage but it is not accurate. The voltage might be 10% wrong.
It can not measure the current for the pump
Thread summary (for future people with similar problem):
Issue: The reading of multimeter is showing readings that are not normal.
Solution at the end:
I used a battery supply to replace the AC/DC power supply.
Key take away:
There are two types of power supply that we have to take note, LED power supply and normal power supply, can refer link below for further explaination.
Rolson 27259 is the cheapest possible multimeter, which can cause low accuracy for its reading.
Power supply is causing the problem instead of the motor.
