i am familiar with arduino and have coding skills yet I greatly lack electronic knowledge. i am trying to drive a solenoid through the arduino, and strangely it works for a while then it stops working. here is my schematic. i am using TIP120, 1K res, and 1n4004 diode just as in the schematic. as the solenoid, i have a push solenoid that is branded as "IDI DAYTON OH 9810 12 VDC" on the sellers website. and on the solenoid it says "IDI DAYTON OH 0237 381814-044A 3964-7706a". and i am using two 9V batteries serially connected as an external power source. i am sure i have connected the circuit properly, i have also made a fellow friend from microelectronics test all the connections and currents with a multimeter while it was connected to the arduino with the simple blink uploaded. the funny thing is the solenoid first starts off working properly but then it dies off. power of the pushes gets degraded after a few pushes then it comes to a halt. nothing is burned or damaged, everything is intact and if you let the solenoid rest for some time, and then connect again, it works again. by working i mean just about 3-6 proper pushes and then it dies off. i am so very frustrated, as i can't figure out what the problem is. if anyone has any ideas or insights, it would be very very appreciated.