1. Current Sensing Mike Ambrisco

2. Background All current sensing devices require being in series with the circuit. The easiest way to find current is by adding a.1 Ω resistor or smaller into the circuit and measuring the voltage across, and divide it by the resistance.

3. Types of Sensors Shunt Resistor ◦ Added known resistance into the circuit in series.  Uses a small,.1 Ω or smaller resistor to minimize total voltage drop.  Measure the Voltage drop across the resistor.  Using ohms law [V=I*R] you can rearrange the formula to find I [I=V/R]  V= Voltage, I=Current, R=Resistance. Op Amps ◦ Uses the Shunt Resistor ◦ Outputs a voltage  Can be calculated to show calculated current as output voltage. Micro Processing ◦ Uses the Shunt Resistor and Op Amps ◦ Uses the most power ◦ Can display output on LCD display ◦ Easily customizable and easily modified

4. Cost A Shunt resistor is very inexpensive. ◦ 5 to 20 cents. A Op Amp is also inexpensive. ◦ Up to $1. A Micro Controller with LCD display. ◦ $20 to $100.

5. Basic Shunt Resistor Setup V1 – V2 Shunt = Current V1 V2

6. Simple Op Amp Sensors http://www.analog-europe.com/215801634%3Bjsessionid=WGUIE44PFGWTFQE1GHRSKH4ATMY32JVN?printableArticle=true www.analog-europe.com

7. Micro Processer Setup Micro Controller A2D Converter LCD Display