[PIC] PIC controlled wiper motor current draw problem

[showmesomeluv]

hi everyone,

I got this problem that, when trying to test my wiper motor on work load with 12v 3 amps to a controlled direction with relays (refer below for schematic i found on the internet), the motor won't work. But when testing it directly with the source alone, it runs smoothly.

By the way, i already read the current output under load, it is 1.3A only, but my motor needs more.
Should i get a higher ampere source? or?...

 

[ernpao]

Does your relay toggle properly? Maybe you can try taking the tip120 out first and shorting the relay pin connected to the tip120 to ground. Your motor should turn and you should be able to change the direction if you can control the relay with the arduino. If this is the case, the problem is most likely with your tip120 driver and not the power supply (assuming that you've also double checked all your connections).

 

[showmesomeluv]

My relay works properly, i tried this circuit in my smaller dc motor and it runs just fine in both direction. =/

 

[Kurenai_ryu]

it seems your TIP120 needs at least 12mA in base to saturate the transistor (well in theory you need at least 3mA but the datasheet says otherwise) if you are triggering from a 5V out (PIN4 ON/OFF), best, change the 1K resistor to a lower value (minimum 250ohm but it seems too low) test with some values maybe 820ohm or 750 ohm, and see if the current gets higher...

or change that transistor...