This circuit provide automatic current limiting up to 8.4A. Unlike current limiter that uses only a resistor, this current limiting circuit doesn’t drop the voltage, or at least keep the voltage drop at minimum, until a certain current amount is exceeded. This current amount limit is adjustable from 1.4 A to 8.4A using a potentiometer. You can modify the component value to give different current limiting range. Here is the circuit’s schematic diagram:
The resistor R1 is there to sense the current. At R2 potentiometer at minimum resistance (the center tap connected to R1), if the current drawn by the load reach 1.2A then the voltage across R1 reach 0.6V and Q2 begin conducting, thus shorting the base voltage of Q4 to ground. This shorting action reduce the base current and therefore reduce the output voltage sensed by the load, and prevent the current to flow further. If you need the current limiter to limit at lower threshold range, you can change the R1 to 1R and you’ll get about 0.7A to 4.2A adjustment range.
Because of the power dissipation capability of 2N3055 transistor, at the worst case that the load is shorted to ground (zero resistance), if you limit the current to 8.4 A then the circuit can handle maximum source voltage of 14V, while limiting the current at 4.2A can handle up to 27V source voltage. The maximum voltage can be handled by this circuit is 60 volt, but at that maximum voltage you can only safely set the current limit at 1.9A in the extreme condition, when the load is shorted to ground. Please make sure the Q1 transistor has sufficient heat sink. [Circuit Schematic Source: Designed by FreeCircuitDiagram.Com]
Possibly Related Articles:
- Single Chip Thermocouple 4-20mA Current Loop Transmiter Circuit
Thermocouples give many benefits compared to thermistor/RTD (Resistance Temperature Devices). Some advantages of thermocouple are their wider temperature range, their reliability, and their consistency over long period of time. In... - Adjustable 0-30V Power Supply
The first thing you must have in your workshop/lab is power supply. In experimenting many new electronic circuit design, it is easier if you have a flexible adjustable power supply.... - Pulse Generator (Oscillator) With Adjustable On-Off Period Using CA3130 Op-Amp
One of the interesting features of CA3130 op-amp is its high input resistance, because using such high input resistance, we can build an astable multivibrator with high R/C ratios. The... - Variable High Power “Resistor” For Power Supply Testing
Current handling capability of a power supply system often needed to be checked. Finding high power rated variable resistor to provide variable load testing might be difficult. There is wire... - Current Amplifier Using CA3140 Op-Amp
Current amplifier application need very low input bias current, and CA3140 is one of suitable op-amps for this purpose. The circuit's schematic diagram is shown in the figure below. In...
| DESIGN BY 