First of all, I'm a new hobbist trying to learn how to do these sort of things. So I'll try to explain my problem as best as I can!

I'm trying to use my Arduino, via a mechanical switch (Illustrated as button) to send a signal to the base of my transistor, in order to make my solenoid(Illustrated as a motor) respond.

I have connected the ground to the emitter, the "solenoid ground" to the collector and the positive wire of the solenoid connected directly to the battery. The base is connected with a 1k resistor to an arduino output pin.

Seen in the sketch below. enter image description here

So my problem is for some reason the transistor is only outputting 4,7 volts to my solenoid, is there something that I have misunderstood? Do I need to use another type of transistor?

I've followed this picture, to understand the difference between the pins of transistor. Mine is named: 2N2222A H331, is it the same? enter image description here

I tried making a sketch more, this is my first time doing it so i hope it's not too confusing. enter image description here

  • \$\begingroup\$ H331 is just a manufacturing date or batch code, you can safely ignore it. \$\endgroup\$ – Finbarr Jan 29 '18 at 10:19
  • \$\begingroup\$ Cartoon diagrams like the one in this question are frowned upon here on Electronics.SE. Next time, click the circuit diagram button while editing your question, and add a proper schematic. Being able to read and draw proper schematics is a life skill. \$\endgroup\$ – Dampmaskin Jan 29 '18 at 10:19
  • \$\begingroup\$ @Dampmaskin Thank you very much for the information. I'll look into it. The reason I'm using this cartoonish style currently, is beacuse it's closer to my reality and what I understand and have experience with. :) I'm not that indepth yet, but soon enough! \$\endgroup\$ – Artonn Jan 29 '18 at 10:31
  • \$\begingroup\$ Have you checked the battery voltage while powering the solenoid? Is the battery voltage dropping? \$\endgroup\$ – HandyHowie Jan 29 '18 at 11:07
  • \$\begingroup\$ You should really find a tutorial and try implementing a few existing schematics before designing your own. \$\endgroup\$ – Dmitry Grigoryev Jan 29 '18 at 11:57

1) Your transistor is backwards - emitter and collector reversed. 2) You need a reverse-biased diode across the motor/solenoid.

Incidentally, your 5V regulator does nothing.

  • \$\begingroup\$ Hi henros. I've tried pulling the transistor out and simply rotate it and plug it in, so far it displays a little higher voltage closer to 5 now, but not the 9v I was expecting. Sorry if I understood you wrong. :) I only have 1N4007 diodes laying around atm, can they do the job? \$\endgroup\$ – Artonn Jan 29 '18 at 10:28

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