I have a Vishay Reflective Optical Sensor (TCRT5000L) which I would like to use to measure the RPM of a rotating shaft. The Datasheet for the TCRT5000(L) is here, and an "application" document is here. In the application document, there is a simple circuit diagram on page 11 that looks like it'll suit my purposes, but it uses an "operational amplifier". It doesn't really specify the exact component, and I'm not clever enough to work which op amp it is from the description, which says: "Special attention must also be made to the downstream logic gate. Only components with a low input offset current may be used. In the case of the TTL gate and the LS-TTL gate, the I LH current can be applied to the sensor output in the low condition. At –1.6 mA or –400 ?A, this is above the signal current of the sensor. A transistor or an operational amplifier should be connected at the output of the sensor when TTL or LS-TTL components are used. A gate from the 74HCTxx family is used." So after my initial excitement of finding a circuit diagram to follow, I am now stuck.
Would anybody be able to point me in the direction of what kind of transistors or op amps would be suitable for this circuit?
Also, in case it helps in some small way, on page 14 of the application document there are more circuit diagrams but these are for 10V circuits using op amps or transistors.
Many thanks in advance for any advice you can offer this newbie. Candice