If a 5 Ohm solenoid is connected to a 1.5 V AA battery, the resulting current will be 300 mA. For a 1000 mAh battery this should provide about 3.3 hours of operation. Is it practically possible to connect a 5 Ohm solenoid to a stabilized DC power adapter with 1.5 V output? Will the voltage still be 1.5 V with such low resistance load?
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2\$\begingroup\$ A DC adapter capable of supplying 300mA at 1.5V would, of course, work. That is Ohm's Law in action. Maybe if you give a specification for the solenoid, at least a link to its datasheet, and explain what you are trying to do then people can help. I think a solenoid specified for 1.5V is unusual. \$\endgroup\$– gbulmerCommented Aug 3, 2016 at 17:20
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2 Answers
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If a 5 Ohm solenoid is connected to a 1.5 V AA battery, the resulting current will be 300 mA.
Correct.
For a 1000 mAh battery this should provide about 3.3 hours of operation.
It probably won't. You need to read the datasheet and see at what discharge rate the 1000 mAh figure is rated. E.g., It may be at C/10 (100 mA) or C/20 (50 mA). The mAh rating will be reduced at higher discharge rates.
Is it practically possible to connect a 5 Ohm solenoid to a stabilized DC power adapter with 1.5 V output?
Sure, but why? The solenoid will generally be tolerant of an unregulated supply such as full-wave rectified, un-smoothed DC. There may be no need for regulation unless the supply voltage varies too much.
Will the voltage still be 1.5 V with such low resistance load?
Yes, provided the power-supply current rating is greater than 300 mA.
answered Aug 3, 2016 at 17:22
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If the power adapter is capable of supplying 300mA (it will say what its output current capacity is on the label) then it will. If it is not capable of 300mA, then it won't. I don't think I've seen any DC output adapters with that output voltage though.
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\$\begingroup\$ There are DC adapters with switchable output voltage. The problem is the output voltage depends on the load. I am not sure if the correct way is to set the adapter to 9V to get 1.5V on the solenoid. \$\endgroup\$– bkxpCommented Aug 3, 2016 at 17:14
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\$\begingroup\$ @bkxp - The output voltage will drop significantly if the load demands more current than the DC adapter can supply. Use Ohm's law. If you put 9V across a 5 ohm load, then 9/5A will flow. If the DC adapter can supply over 1.5A, then the voltage will not drop. However, the solenoid might get very hot. \$\endgroup\$– gbulmerCommented Aug 3, 2016 at 17:18
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\$\begingroup\$ @bkxp: If you allow the solenoid to draw so much current from the 9 volt supply that it drops to at 1.5 volts across the solenoid, you might find that the supply will overheat. \$\endgroup\$– FiddyOhmCommented Aug 3, 2016 at 17:45