Help needed with Phototransistor L14G3

Hi

I am using photodiode TIL 38 as an infrared source and using L14G3 as a detector. Between the diode and the detector I am keeping my finger so that the output at collector will vary according to the change in blood volume in the finger. By this i intend to measure the heart rate.

Can anyone help me in biasing the ckt. because I think I am not biaising it correctly. I am unable to get any output at the collector(it's totally random and no way near to what I am expecting) , also sometimes 50Hz wave (power supply noise) comes at the collector.

If anybody has any idea how to overcome these problems then do reply.

Since you didn't attach your schematic then we can't troubleshoot your circuit.
There are a few projects like that on a search in Google. One explains how the phototransistor must be shielded from the flickering of AC lights.

Google for 'hemon' a PIC based project, it includes just such a sensor.