1Amp constant current source for milliohm meter
2 layer board of 2.36 x 2.17 inches (60.0 x 55.0 mm)
Uploaded:
August 11, 2015
Shared:
August 11, 2015
Total Price:
$25.55
1Amp constant current source. You can use this constant current source to measure very low resistances since the voltage drop is R=V/I i.e. 1mV over each 1mΩ.
To guarantee correct operation and not thermally overstress IC1, U1 and R5 keep input voltage between 6.5V≥Vin≥9V
Calibrate with P1 to achieve exactly 1Amp at output with short circuit load or 1V with 1Ω resistor load.
BOM: IC1 LM317T; U1 LT3083; R1 1K6; R2 3K9; R3 18K; R4 910R; R5 1R 0.1% 1W; R6 130R; P1 5K 10turn precision poti; C1 10µF/5V tantal; C2 15pF ceramic; C3 10µF/5V tantal; LED1 green; heatsink of maximum 3K/W or lower for IC1, U1 and R5;
For schematics look here: https://www.dropbox.com/s/cs31b9lijhswvi1/1Amp%20constant%20current%20source.pdf?dl=0
For thermal calculation look here: https://www.dropbox.com/s/gdbk54ipaouoct8/1Amp%20current%20source%20thermal%20calculations.pdf?dl=0
Have fun!
1Amp constant current source. You can use this constant current source to measure very low resistances since the voltage drop is R=V/I i.e. 1mV over each 1mΩ.
To guarantee correct operation and not thermally overstress IC1, U1 and R5 keep input voltage between 6.5V≥Vin≥9V
Calibrate with P1 to achieve exactly 1Amp at output with short circuit load or 1V with 1Ω resistor load.
BOM: IC1 LM317T; U1 LT3083; R1 1K6; R2 3K9; R3 18K; R4 910R; R5 1R 0.1% 1W; R6 130R; P1 5K 10turn precision poti; C1 10µF/5V tantal; C2 15pF ceramic; C3 10µF/5V tantal; LED1 green; heatsink of maximum 3K/W or lower for IC1, U1 and R5;
For schematics look here: https://www.dropbox.com/s/cs31b9lijhswvi1/1Amp%20constant%20current%20source.pdf?dl=0
For thermal calculation look here: https://www.dropbox.com/s/gdbk54ipaouoct8/1Amp%20current%20source%20thermal%20calculations.pdf?dl=0
Have fun!
