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test instruments projects
BH9005
power supply +5V with adjustable current limit

The power supply is made with power 5-pins IC stabilizator Sanken 9005. expanded with adjustable current limit circuit. Sanken 9005 has droupout 1Volt at current 4A. Neccessary input voltage should be between 6.5 to 7 Volt. Pin 2 of stabilizator allows setting of output voltage. If you use precisious 10-turns trim, you will be able to setup output voltage with resolution of tenth of microvolts (tested with Keithley 2000).

The stabilizator is switched off with signal over 2V on pin 3. This signal is produced by comparator which is made from operational amplifier. It compares adjusted potentiometer voltage with voltage from resistor 0.1Ω. The signal from resistor 0.1Ω is comming through 10:1 operational amplifier. Output voltage 1 Volt represents current 1A at resistor 0.1Ω.

Comparator input and operational amplifier's output is connected over switch to voltmeter. Actual current or adjusted current limit is displayed. With 10-turn potentiometer is adjustable current limit resolution 10mA.

The PCB is single sided, size 70 x 40 mm.



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