spcl-0003-x22 board:ad625 instrument amp

[mike friedrichs]

1. the schematic; SPCL, dos not indicate what potential pin 7 of ad625 is tied to. I assume this is tied to circuit ground. is this correct.

2. to change the gain of the amplifier a resistor needs to be attached to pins 2 and 15. is there a solder pad available that I can't identify.

thanks,
mike friedrichs

[tomn]

Originally posted by mike friedrichs
1. the schematic; SPCL, dos not indicate what potential pin 7 of ad625 is tied to. I assume this is tied to circuit ground. is this correct.

Correct. Pin 7 of AD625 connect to the circuit ground.

2. to change the gain of the amplifier a resistor needs to be attached to pins 2 and 15. is there a solder pad available that I can't identify.

Pin 2 and Pin 15 connected to 19.6K resistor R8 and R9.
You can see those traces on the component side of the board. Adjusted VR1 (10K Pot.) to change the gain.

[mike friedrichs]

1. the schematic; SPCL, dos not indicate what potential pin 7 of ad625 is tied to. I
assume this is tied to circuit ground. is this correct.

Correct. Pin 7 of AD625 connect to the circuit ground.

2. to change the gain of the amplifier a resistor needs to be attached to pins 2 and 15,
is there a solder pad available that I can't identify.

Pin 2 and Pin 15 connected to 19.6K resistor R8 and R9.
You can see those traces on the component side of the board. Adjusted VR1 (10K
Pot.) to change the gain.

VR1 is connected to pin 3-4, which corrects the input offset. resitance is required between
pins 2-15 to adjust gain, per analog data sheet.