Where Does Current Go With a 4V Servo?

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Discussion Overview

The discussion revolves around the behavior of current in a circuit involving a 4V power source and a 4V servo that requires a running current of 200 mA. Participants explore the implications of using a power supply with a lower current rating than the servo's requirement, as well as the role of capacitors in this context.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant questions where the current from a 4V, 50 mA power source goes when connected to a 4V servo requiring 200 mA, suggesting it may heat the motor or be stored in a capacitor.
  • Another participant notes that using a power supply that cannot meet the servo's current requirement could lead to under-serving the servo, and asks if the original poster has tested this setup.
  • A participant explains that if the servo is active continuously, a capacitor may not be beneficial, but it could help if the servo is only active part of the time, depending on the capacitance size.
  • One participant clarifies that capacitors have maximum voltage ratings and will stop charging once the voltage at their terminals equals the supply voltage, countering the idea of a capacitor 'bursting' with current.
  • Another participant uses a water analogy to describe how current circulates in a circuit, emphasizing the continuous flow of current around the circuit.

Areas of Agreement / Disagreement

Participants express differing views on the effectiveness of a capacitor in this scenario and whether the power supply is adequate for the servo's needs. The discussion remains unresolved regarding the best approach to take with the described setup.

Contextual Notes

There are assumptions about the operational characteristics of the servo and the power supply that are not fully explored, such as the duration of servo activity and the specific capacitance required for effective operation.

pug
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Hi I am trying to do a DIY with a servo and I was wondering...

If I have a power source (e.g. 4V with 50 mAmps) connected to a 4V servo with a running current requirement of 200 mAmps...where will the current from the power source go? Will it just heat the motor of the servo? Or if there was a capacitor will the capacitor collect the current and then periodically discharge it to the motor?

I have been taught that voltage is akin to the 'height' of the electron and current is the amount of electrons that are flowing. So if the voltage is correct will the electrons compile in the capacitor like a dam until it 'bursts' or discharge?

thank you for any help!
 
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If your servo requires 200 mA, and you picked a power supply that can only deliver 50 mA, then you could be under-serving your servo. What little current your power supply is providing will still go into the servo. Have you tried it yet? Please report on what happens.

If your servo is always doing something, a capacitor will not help. If your servo is only active, say less than 25% of the time, yes a right-sized capacitance will help (depends on how long the servo is continuously active).

Why use with an undersized power supply to begin with?
 
pug said:
will the electrons compile in the capacitor like a dam until it 'bursts' or discharge?

The circuit should not over-voltage the capacitor, capacitors have max voltage ratings. A capacitor voltage will rise at it charges, and it will accumulate less and less charge as the voltage at the terminal connected to the charging voltage source rises. The capacitor should not burst or overcharge, it will just get full and then current will stop flowing because the voltage at the input terminal of the capacitor will equal the voltage at the output of the power supply.

The below is more elaborate / formal / better explanation.

http://www.electronics-tutorials.ws/rc/rc_1.html
 
pug said:
Hi I am trying to do a DIY with a servo and I was wondering...

If I have a power source (e.g. 4V with 50 mAmps) connected to a 4V servo with a running current requirement of 200 mAmps...where will the current from the power source go?
In general, current just goes around and around the circuit. Using the water analogy, it's like a circular piping loop.
 

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