This is Adjustable Constant Current Regulator circuit. This circuit can be used in a bench power supply to prevent the circuit that are tested from being damaged. This circuit can be adjusted to any value from a few milliamp to about 500mA. The max current is 500mA because it is the limit of the BC337 transistor in the current-limiting part of the circuit. Here is the schematic diagram of the circuit:
The input voltage (supply) has to be 5.25v above the required output voltage, because of 1.25v across the current-limiting section and Approximately 4v is dropped across the regulator. The LM 317 3-terminal regulator will need to be heatsinked. the LM series of regulator is suitable for this circuit because they have a voltage differential of 1.25v between “adj” and “out” terminals. the LM317 can be replaced by 7805, however the losses in the BC337 will be 4 times greater as the voltage across it will be 5v.
For example, to charge 4 Ni-Cad cells, just connect them to the output and adjust the 500R pot until the required charge-current is obtained. The charger will charge 4 Ni-Cad cells at the same current. But, don’t forget to turn off the charger before the cells are fully charged or the battery will be over-charged. [Source: talkingelectronics.com]
Possibly Related Articles:
- 5 A Constant Voltage-Constant Current Regulator
A constant voltage constant current (CVCS) regulator doesn’t mean a system with a constant load, since there will be no regulation in such case. What we call CVCS regulator is... - Constant Current Constant Voltage SMPS (Switch Mode Power Supply)
This constant current constant voltage SMPS can be used to efficiently charge a battery. This circuit gives 7.2V at constant voltage mode, and 600 mA at constant current mode. Here... - Variable (Adjustable) Current Limiter Circuit
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... - Adjustable Shunt Regulator
This shunt regulator acts like a Zener diode, but we can adjust the voltage (via a potentiometer). Here is the schematic diagram of the circuit: When the maximum load current... - Adjustable 1.5A Step Down 1.5 MHz Switching Regulator
Usually, when an high heating of the application environment is occurred due to the power dissipation, we use high current linear solution to solve that problem. But, we can solve... - Programmable Current Source/Regulator
This is a simple circuit of programmable current source/regulator. This circuit is used to generate current. Here is the schematic diagram of programmable current source/regulator : This circuit uses L... - Foldback Current Limited High Voltage Regulator
This circuit is high voltage regulator which has foldback current limiter protection. This circuit uses LM10 comparator with voltage reference, and this core integrated circuit is connected directly to high... - How Discrete Voltage Regulator with Current Limiter Works
This discrete voltage regulator has complete features that is equivalent with modern voltage regulator integrated circuit (IC). It’s not cheaper if you build discrete one like this, but it’s always... - 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.... - LM3404 Constant Ripple LED Driver
To take an input voltage of 24VDC ±10% and drive 1A through as many LEDs in series as the maximum output will allow, the circuit shown in the schematic diagram... - Sealed Lead Acid Battery Charger: Dual Step Current Charger Mode
All of the necessary circuitry to optimally control the charge and hold cycle for sealed lead acid battery can be implemented using UC2906 series of battery charger controllers. These integrated... - Adjustable High Power LED Driver
A circuit that can drive three to four high power LEDs is shown on figure below. The ADP 1610 is an adjustable boost regulator. The voltage headroom and current for...
| 
