Hey guys just need to the exact MOSFET n-channel as shown in the picture above. I know there are a few but I specifically need this one please thanks.
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Hi Adam,
I can see you made two posts that are quite similar, is it possible to get the whole schematic and the values of the components? Without any more information it is impossible to find the parts you are after.
If its come from a website sending through the link would be the best way to find information
Hi Adam
The Mosfet is labeled Q1. Is there any parts list. It could be any Mosfet switch that can safely handle the solenoid current. Being driven from Arduino it would have to be a logic level device. Core I think have a general purpose device all mounted up on a little board, Freetronics unit I believe. I would recommend inserting a 1kΩ resistor in series between the Arduino output pin and the Mosfet Gate. I have been into the reasons for this before and am not going to do so again. Just believe me and put it there.
By the way That piezo device (I think) or buzzer being driven by the opto coupler (4N35) is not going to work very well wired like that.
Cheers Bob
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I’d play it safe and use this P30N06LE
We can see that when V_gs is 3.3V the transistor is not “fully on” but happy to pass many amps. Certainly enough for a small solenoid.
In the unlikely event the solenoid L1 uses <= 100mA, you could use a 2N7000
A word of caution
Solenoids are often rated for about 10% duty. If you keep the solenoid on for more than 10% of the time it may become very hot
Happy Making 
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Hi Michaell
If it is the 5V version of the Pro Mini it would be better.
It is true that the graph you have marked up shows 10A for Vgs of 3.3V. But I would say think this is very borderline. The graph on the left shows another angle. At Vgs 3.5V and 10A the S to D voltage is 0.5V which means a required dissipation of 5W. At Vgs of 3V this voltage is shown as 10V thus the dissipation is 100W. A pretty steep curve in this area.
If the ProMini is the 5V version this numbers are much better and I don’t think you would have any trouble. Adam in his wisdom has neglected to indicate which version of the ProMini has been used or what the battery supply is.
Cheers Bob
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Hey @Adam223138 - what’s the spec of your solenoid? Do you have a link?
I assume we’re only working with a low-power solenoid here, something less than two amps.
As for power dissipated, the R_ds_on is not plotted for V_gs = 3, but I reckon we can expect will be <100mOhm which would (at 1 A) give a dissipation of 1[A]^2 * 0.1[Ohm] = 0.1W worst case.
Or 0.4W for a 2A solenoid 
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Hi Michael
No bur the voltage drop is in the top left graph posted.
The on resistance at 3.5 V Vgs can be calculated, at 10A it is 0.5V which is 50mΩ.
Below this Vgs this increases quite rapidly so from the graph at 3V Vgs it increases to 1.0Ω. This resistance is a function of Vgs and is still there irrespective of what sort of current is switched.
I am a firm believer of switching these devices hard on to minimise heat problems and stand by my statement that at 3.3V this Mosfet I would consider marginal at best.
I think this device may be considered as a “logic level” unit (5V). I would base this on another part of the same spec sheet.
which interestingly quote figures for 5V and 10V.
Personally if I were to need to use this device and only had a switching voltage of 3.3V i would tend to find a way to switch at least 5V to the gate for greater reliability.
This is a pretty versatile switch for low currents but once again the numbers are only quoted for 10V, 5V and 4.5V Vgs and the on resistance is quite high, up into the ohms area.
Cheers Bob
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