AN-1003/AN-1005/AN-1002 channels OPT12 signal conditioner

The signal conditioner in your anemometer has different setups according to the user's request.
When any customer is purchasing a new anemometer, we always ask them about the frequency bandwidth they would use. As all of us know, opening a too wide frequency bandwidth would cause higher noise at the output.
However, sometimes a new user is using the system or the research work requires higher or lower bandwidth.
The following guide would allow you to modify the bandwidth of the signal conditioner per your current research specifications.
The bandwidth of any amplifier (including Option 12) is changing according to the gain. Higher gain will always lower the frequency bandwidth (because the RC constant is bigger). In addition to that, higher bandwidth cause higher output noise. The following guide would allow you to make your own decision about the signal conditioner bandwidth, considering the noise that would be added.
This is a picture of Option 12 signal conditioner:

The capacitors C1, C2 and C3 determine the bandwidth of the signal conditioner. The following tables contain few common setup of signal conditioner as shipped to our customers during the last 28 years:
Basic setup = Low bandwidth, low noise. -3dB point compared to output of 10V P-P @100Hz

Setup 2 = Low bandwidth, low noise. -3dB point compared to output of 10V P-P @100Hz

Setup 3 = High bandwidth@low gain, medium noise. -3dB point compared to output of 10V P-P @100Hz

Setup 4 = medium-low bandwidth, low noise. -3dB point compared to output of 10V P-P @100Hz

Setup 5 = High frequency bandwidth, low noise. -3dB point compared to output of 10V P-P @100Hz

Setup 6= Highest Frequency, higher noise. -3dB point compared to output of 10V P-P @100Hz

In order to change the capacitors, the cover of the channel module must be removed using 4 screws and Option 12 board must be removed gently using a flat screwdriver inserted below its socket.
After the capacitors were changed, the boards should be carefully examined to make sure that no drops of solder were left on the board. Flux drops can be cleaned using a piece of cotton with some Acetone or PCB cleaner spray. After the board is clean and dry, it should be inserted back into the channel module: Selector and trimpot should be inserted into the panel holes and then the electrical pins should be matched to the socket pins below and pressed into them. The plastic spacers should also be pressed into the appropriate holes on the board.
In some setups, U2 must also be changed.

If you cannot find capacitors in the right values, please call us and we will prepare them for you at a low cost of US$25.- per each Opt. 12 board including socket pins, U2 chip and shipping.

Please keep in mind that the anti-aliasing low pass filters are also used for limiting your frequency bandwidth and they should also be changed if you are looking for a higher frequency bandwidth.

All results are +/-10% or according to capacitor tolerance – whatever is higher.
Noise was measured with input connected to GND
When measuring noise, RMS=PTP/6.2 

We sell sets of capacitors + chips for modification of old channel modules per your current research demands. Please consult teh factory for more details.

Avi Aharoni
A. A. Lab Systems