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need clarification on opamp installation — Parallax Forums

need clarification on opamp installation

mleadermleader Posts: 8
edited 2009-12-02 19:50 in Learn with BlocklyProp
I have a question regarding the dual power supply necessary to build this circuit. The instructions say to use a 9v battery on the BOE board, but if you connect a 9v battery to the BOE board you cannot plug in the cord from the AA battery power pack.

Would you use 2 9v battery clips with tinned leads and connect the positive lead of the 1st clip into VIN and the negative lead to VSS. Then connect the positive lead from the second clip to VSS and the negative lead to the negative supply input of the opamp??

These are the instructions on the stamps in class mini project page:


" To get good amplification with one opamp circuit, the opamp chip can needs two supplies, a negative voltage and a positive voltage. By plugging a 9 V battery into the Board of Education's battery clip, this will give you + 9 V at the Vin sockets above the breadboard. If you measure this with a voltmeter, connect the positive lead to Vin and the negative lead to Vss. To make the -9 V supply, simply connect the positive lead of your second 9 V battery to Vss. The negative lead will then supply -9 V. Most 9 V battery clips with tinned leads have a red lead connected to the battery's positive terminal, and a black lead connected to the battery's negative terminal. Verify this with a voltmeter. If the red lead is indeed the connected to the 9 V battery's positive terminal, then connect the it to Vss, and set the black lead aside. You will connect the black lead to the opamp's negative power supply input when you build that circuit."
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