Hello
I'm almost embarrassed to post this very basic question, but my knowledge of electronics is so poor that I'm stuck. I'm sure that my reasoning is faulty, so if someone could just point out the error, I'd be grateful.
I have a 7.4V lipo that I want to use to power the receiver and 3 servos in a RC glider. The receiver and servos take between 4.8V and 6V. So, I figured I could just put a resistor in series between the battery and the receiver to drop the voltage from 7.4V to 6V (see pdf attached). I used another battery (5V) to power the receiver and servos to measure the current they draw. When the servos are not moving, the current is about 50mA. When all the servos are moving, the current averages around 100mA with the occasional peak of 140mA.
So, I figured I want to drop 1.4V over the resistor to give me 6V for the RC gear.
V=IR. When the current is maximum, the resistor should be 1.4/0.14 = 10 ohms. So far, so good.
Then I thought I'd better check for the minimum current of 50mA. So,
V=IR. V = 0.05*10 = 0.5V.
Here is the problem. Does this mean that only 0.5V will be dropped over the resistor at minimum current, leaving 7.4V-0.5V = 6.9V for the RC gear? If so, I'll blow them up as they only take 6V maximum.
I'd be very grateful for some clarity.
I'm almost embarrassed to post this very basic question, but my knowledge of electronics is so poor that I'm stuck. I'm sure that my reasoning is faulty, so if someone could just point out the error, I'd be grateful.
I have a 7.4V lipo that I want to use to power the receiver and 3 servos in a RC glider. The receiver and servos take between 4.8V and 6V. So, I figured I could just put a resistor in series between the battery and the receiver to drop the voltage from 7.4V to 6V (see pdf attached). I used another battery (5V) to power the receiver and servos to measure the current they draw. When the servos are not moving, the current is about 50mA. When all the servos are moving, the current averages around 100mA with the occasional peak of 140mA.
So, I figured I want to drop 1.4V over the resistor to give me 6V for the RC gear.
V=IR. When the current is maximum, the resistor should be 1.4/0.14 = 10 ohms. So far, so good.
Then I thought I'd better check for the minimum current of 50mA. So,
V=IR. V = 0.05*10 = 0.5V.
Here is the problem. Does this mean that only 0.5V will be dropped over the resistor at minimum current, leaving 7.4V-0.5V = 6.9V for the RC gear? If so, I'll blow them up as they only take 6V maximum.
I'd be very grateful for some clarity.
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