I am using an Arduino UNO. A relay is connected to run a 6V dc pump. i even used an external 9v battery to run the pump.
But whenever my pump turns on my lcd display goes blank. If i disconnect the dc pump display works fine even when the relay is on.
Can some one please help me with this.
This we get very frequently here.
Have you got a reverse biased diode across your pump?
If not you need one.
No. So I will need a diode. Can you please tell me which diode the ratings . If i can't find a diode do i have any alternative.
When you say across that means in parallel with motor right.
Correct. With the diode's Cathode to the positive end of the motor, and the Anode to the negative side of the motor. The cathode end is marked with a band.
About the same current rating (or more ) as your motor.
If you can't find a diode then you have no chance of finding anything else that would do the job, as those are quite obscure and expensive device. Diodes cost pennies.
Edit please note the correction to which way round the diode should go. It is arranged so that normally current will not flow through it. And then when the mother produces a kick back reverse voltage it is clamped.
Thank you sir.
I will try this tomorrow.
If i have any problems I will ask you.
I am new to this. So thanks once again.
Can you show me a diode that i could use.
There are very different ratings and really confusing.
Here
1N4001
It works perfect. But my motor runs little slow.
It's okay right.
That is nothing to do with the diode. It is possible that the motor is taking too much current than the supply can give, or the wires are a bit thin for the current, or that the solderless bread board is not making a good contact. It is not wise to let it handle too much current.
Did you ever get the diode the wrong way round? If so you could have pitted the relay contacts and caused them to have a too high resistance. Have you another relay you could try?
The operating current of the pump is 130 to 220mA, a 9V smoke detector battery will not last very long.
Do you have a DMM?
Thanks.. Tom... 
I don't have a dmm
Then you need to get one. They are only $10 or so from a thrift store.
Okay sir
Thank you for you help now my project is almost done.
It wouldn't be possible without you.
If i face any problem I will message you.
Please post in the forum, that way others will be able to benefit from the thread as well.
If you want to alert me to a post then just use my forum name preceded by an @ and I will receive a notification.
What about using a capacitor in parallel with the display.
So that motor runs at good speed .
A capacitor can not compensate for a weak power supply, or thin wires.
