# Problem with line scan optical sensor drive

#### ronsoy2

Joined Sep 25, 2013
71
I realize this forum is more for connecting up a 555 chip but I thought maybe there is some advanced engineer out there somewhere looking. I have a very expensive line scan CCD sensor from a spectrometer that I would like to get operating. The sensor has zero markings on it so I think it is proprietary. However, there are only 3 wires to it, aside from the power supplies and output signal so it seems like it would be easy to figure out how to drive it.
The picture shows the traced out circuit of the driver. I have a pulse generator connected to the clock pin and a second pulse generator to the base of the transistor. The waveforms on the driver chip are nice and clean and the waveform on the collector of the transistor is clean. (note that this is the original driver board from the spectrometer) The problem is that the CCD output changes for all of the pixels at once! There doesn't seem to be any shifting going on. Covering part of the sensor causes all of the output pixels to change instead of only the ones being covered. I have varied both generators over wide ranges to see if there was some critical relationship but have so far not been able to see any separate changes in the output pixels. Am I overlooking something here?

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#### ronsoy2

Joined Sep 25, 2013
71
Sorry about the mess in the listing. First post. Inserting images is not clear how to do if you screw up!

#### RichardO

Joined May 4, 2013
2,271
Sorry about the mess in the listing. First post. Inserting images is not clear how to do if you screw up!
I get this wrong often enough that it is sometimes easier to delete everything I did and start over.

Part of the trick is to _always_ remember where you have placed the cursor. This is where the image will be inserted. This is my typical error -- I often forget that I have moved the cursor...

#### RichardO

Joined May 4, 2013
2,271
View attachment 139461 View attachment 139462 The sensor has zero markings on it so I think it is proprietary. However, there are only 3 wires to it, aside from the power supplies and output signal so it seems like it would be easy to figure out how to drive it.
Try looking into the sensor through the window. You might find a number on the sensor chip.

Without a part number this is going to be hard. The best I can think is to look at data sheets for similar sensors and see if one has driver circuits that match yours.

Failing that you are stuck with using an oscilloscope to look at the signals in excruciating detail and then reproducing them.

Thanks for looking! I found the trouble. Bad op amp in the video output! It works perfectly now! I'm betting the reason I got this $20k spectrometer on ebay for$50 is one \$3 op amp! OK!