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How do I run a 12V 450mA DC motor using a 12V 1A DC adapter? It is for a small water pump for one of those decoration waterfalls. Should I simply add a (R=V/I) resistor? If so, what is the approximate R value I should go for? Also, where should I put the resistor in the circuit?

user1478983
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    12V motor , 12V supply - the motor needs 450mA the adapter can supply **up to** 1A so everything is fine. The motor only takes the current it needs and as long as the supply can provide it (or more) you don't need a series resistor. – JIm Dearden Aug 29 '17 at 17:36
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    Using a water analogy: my house is connected to the water mains with pressure of 2 bar. I need 1 L/s at 2 bar in my house but the water mains is capable of delivering 300 L/s. Will it destroy my house or the supply station? No. My house will draw only what it needs. – Transistor Aug 29 '17 at 17:44
  • What start up current does it need and will the stall current destroy the adapter? – Andy aka Aug 29 '17 at 17:48
  • @Transistor, why use the water example? My house has a feed of electricity 110V capable of supplying maybe 400 A of current (20 AC outlets at 15A each, plus air conditioner, plus stove and other appliances). If I plug in a 110V/10A electrical teapot, why it doesn't explode or destroy the electrical transformer outside the house? – Ale..chenski Aug 29 '17 at 18:21

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Just plug it in. The wallwart might be able to supply upto 1A but that doesn't mean it always will.

In this instance the voltage is key and they are equal (for a certain definition of equal).