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Is this circuit correct?

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When transistors saturate the Beta reduces to about 10% of the linear range or 10:1 (Ic:Ib) for most datasheets, although super junction ( See Diodes Inc) "ultra low Vce_sat_ devices can be as high as 50:1 in saturation. or 2% of the collector current and then usually have a linear Beta of 500.

EDIT

Your SIM had a solenoid,, but you are using a relay, please me correct your mistakes with specs. on motor, relay, etc. or rela part numbers or links.

With 1mA base current when the transistor comes out of saturation the Beta will increase to >100 typ. with 100mA on collector . If the Solenoid has a DC resistance of 10 Ohms, there will be 1V drop across the coil and 11V across the transister with 1.1W dissipation and it will fry without a large case (TO-220) then may need a heat sink.



Think of all switches, transistors and solenoids as switches with current gain ( output rating/ drive current) Relays can be very efficient as high as 5000 from OMRON while transistors can be very inneficient ( 10% drive or 10:1 gain)

That's why you need to provide a coil resistance spec. then increase your base drive from 2 to 10% of coil current, which may be at least 1 Amp to drive a 1HP motor. JUst a guess, it could be more)

So start all over with specs of ouput power of load, then solenoid then transistor then drivers. then power supply to start a proper design.
 
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I will post the resistance value as soon as I get the solenoid. It will take 15 to 30 days as I ordered through free shipping.
 


1st link says 12V DC Coil ( 22 Watts ) so that is 2A steady state, which usually means >3A on start while moving the solenoid due to mechanical load.

SO start from there

with a 5A transistor and 500mA bias or choose a MOSFET.
 
SunnySkyGuy

Can you please modify the Circuit to work with IRF840 ?
 

From yor posts, you want to reduce the spill of water. It would be naturally that you use a normally closed valve, since a normally open valve would open if the power is lost, and the water will flow.

Of the three valves listed the first is normally open, and the last two is normally closed. The second is a 2W valve, @166mA activated. The last one is a 6W valve, @500mA activated. If you are filling a tank of water, I would assume that the closed time is greater than the open time for the valve. This should mean that using one of the two normally closed valved would be optimal.
 
Yes, I decided to use Normally Closed but I have to use a battery because if main power fails then valve will not open if needed.




Edit : I am going to use 2N3055. It can handle 15A Ic and 1.5A Ib.
 
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I received one Solenoid valve and its resistance is 4.1E. So, current is 12V / 4 = 3A.
 

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