Doing a garden project and want to be able to switch a water pump on/off with my board. So much information I've become a little lost in researching it so I thought I would just ask!
I've seen the relay circuit pdf, but is the transistor, diode, etc necessary if its just a 5v relay? Such as a Potter & Brumfield 3-8 VDC Input 3A 60VDC
With the pump wired to its own power source and such I shouldn't have to worry about any kind of kick back right?
n3wb questions I know, appreciate any guidance here!
Cooper4891:
Doing a garden project and want to be able to switch a water pump on/off with my board. So much information I've become a little lost in researching it so I thought I would just ask!
I've seen the relay circuit pdf, but is the transistor, diode, etc necessary if its just a 5v relay? Such as a Potter & Brumfield 3-8 VDC Input 3A 60VDC
That would depend on how much coil current the 5vdc relay draws. Some will work directly from a output pin but maybe not with the contact current specification you require. Probably best to just use a transistor switch to control the relay.
With the pump wired to its own power source and such I shouldn't have to worry about any kind of kick back right?
Correct, a relay has complete isolation between it's contact circuit and it's coil circuit. Lefty
n3wb questions I know, appreciate any guidance here!
retrolefty: That would depend on how much coil current the 5vdc relay draws. Some will work directly from a output pin but maybe not with the contact current specification you require. Probably best to just use a transistor switch to control the relay.
With the pump wired to its own power source and such I shouldn't have to worry about any kind of kick back right?
Could you explain this a little better for me? So as long as the relay doesn't draw more amps than the pin can handle it should be alright? Also, when you say contact current specification, is that the "output" voltage of the relay?
retrolefty: That would depend on how much coil current the 5vdc relay draws. Some will work directly from a output pin but maybe not with the contact current specification you require. Probably best to just use a transistor switch to control the relay.
With the pump wired to its own power source and such I shouldn't have to worry about any kind of kick back right?
Could you explain this a little better for me? A relay has several specifications. One is it's coil operating voltage which in your case you stated it has a 5vdc coil. What you didn't state is how much coil current flows when 5 volts is applied to the coil. The information will be in the datasheet for the relay. If it's more then say 30ma then that exceeds the recommended output current that you should attempt to draw from an arduino output pin. If it's 30ma or less then it is a candidate for direct connection to a arduino output pin. You can't guess at this you must get the information to determine. However I will share that most relays do require more then 30ma coil current, so I would plan on using a transistor and series base resistor between the arduino output pin and the relay coil.
So as long as the relay doesn't draw more amps than the pin can handle it should be alright? Correct, what does yours draw?
Also, when you say contact current specification, is that the "output" voltage of the relay? A given relay will have two specifications that cover it's contact ratings, maximum voltage and maximum current. You should select a relay that has both maximum voltage and current ratings at least double what your loads actual work at. Voltage is not a difficult specification to met but current might be as you first must know the maximum current draw of the devices you are controlling draw.
Thanks for the help!
