I have been asked to create an optical detection system that can monitor the infrared emission intensity of an ignition spark gap by outputting a corresponding 0 to 5V or 0 to 10V output based on spark intensity. The plan is to use the current from a photodiode in conjunction with an amplifier to measure a voltage output. A baseline is to be created by varying the ignition coil primary dwell time and measuring the spark light response through the optical sensor to establish a relationship from sensor output to ignition coil command input.
I ordered the TI TSL260 IR LIGHT-TO-VOLTAGE OPTICAL SENSORS from digi-key hoping this would be a direct fit for my application. The optical sensor detects spark timing and the spark duration; however, the sensor is pegged to the maximum output the moment any level of spark intensity is detected. Is there any way to decrease the feedback resistance and ultimately the gain of the TSL 260 amplifier circuit to change the light detection level of the device? If not, is there any way to add some other type of external circuitry to allow a decrease in light sensitivity? I have also used a 1 meter fiber optic cable to transfer the spark light to an isolated circuit location, but the output still pegs the instant spark light is measured from the cable.
If it is not possible to adjust the sensitivity of the TSL 260 sensor does TI have any other sensors or solutions that would be able to output a varying voltage output for the varying intensity of ignition spark? I do not have specifics regarding the light intensity of the spark, but I do know that the spark's electrical characteristics range from 8000V to 35000V and the energy release is 20mJ to 103mJ applied across a 1/2" air spark gap.
Thanks in advance for any help or suggestions that may be offered.
