Arduino + solenoid powered by on source

[jirik23]

Hello. I would like to power solenoid and arduino with one power source. Is it safe to connect it like it is on the picture? Thanks.
http://resize.like.cz/images/89_24_18_96_22-01-13-11-53-06_1358851986nyx_2.png

[larryd]

What is the resistance of the solenoid?
Its best to label the GND as 0 volts rather than -10V.
What is the current rating of the 10 volt power supply?

[jirik23]

Solenoid: http://www.ebay.com/itm/330850756486?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649
12V 1A

As a power source i need to use 9V battery

[larryd]

I see your solenoid is 12 volts, 1A.
It may not work at 10 or 9 volts.  If it does, your power supply should be rated at at least 1.5 amps
as your controller needs power.
I think I would add a diode & large capacitor across the power supply o/p (may be 470uF) to supply the initial solenoid surge current.

[jirik23]

OK. Thanks a lot. I will try it. I have to buy these components. What about to add 100k pulldown resistor between transistor gate and GND to avoid problems when reseting arduino?