Normally in the equipment such as power source need does electric current to detect or feedback, electric current detects the method of the voltage that resistor is in a sampling of commonly used series connection to go up through amplifier enlarge resistor, if want to rise,detect this place often should use precision to costlier appearance amplifier, feel common to carry puts maladjusted voltage bigger.

 

A few kinds of clever cheap electricity introduce to detect below circuit:

1 dynatron electric current detects circuit

　　

 

If use dynatron simply to guide,connect with end will detect voltaic word, dynatron open wants 0.7V left and right sides, need strings together bigger adoption when electric current is smaller resistor, waste bigger feedback voltage at the same time, method of as above graph, can use less resistance, use up very little tension to be able to detect voltaic I, through adjusting dynatron base Electromechanical block can adjust detected sensitivity. This circuit can be used in the need such as charger to show the place that has charging current.

 

2.Tall sensitivity electric current detects circuit

　　

 

This circuit does voltaic sampling with two diode, sensitivity is very tall, electric current can accomplish dynamic limits very big, compare in high-power or circumstance of tall voltage application appropriate, defect is voltage needs to damage make an appointment with 1.4V.

 

3TL431 electric current returns feed way

　　

 

TL431 price is low, apply in great quantities in the feedback annulus road of switch power source, but its FB voltage is 2.5V, use directly very great sampling resistance wants when doing electric current to feedback, waste voltage. Voltaic feedback comes true with two TL431 in the graph, the electric current that can realize nicety with less sampling resistance feedbacks, if still have voltage feedback network, go up again the voltage feedback circuit of U3.