The couple factor of the reflex sensors is relatively small. Even in the case of good reflecting surfaces, it is less than 10%. Therefore, the photocurrents are in practice only in the region of a few μA. As this is not enough to process the signals any further, an additional amplifier is necessary at the sensor output.
They also illustrate several amplifier circuits further down. It doesn't look like you can directly drive the buffer chip with the sensor output.
A Nano has eight analogue inputs (with buildin pull up resistors).
And eight digital outputs for your relays.
Reflector sensitivity can be set in software.
Leo..
dougp:
Did you catch this in the sensor datasheet?
The couple factor of the reflex sensors is relatively small. Even in the case of good reflecting surfaces, it is less than 10%. Therefore, the photocurrents are in practice only in the region of a few μA. As this is not enough to process the signals any further, an additional amplifier is necessary at the sensor output.
They also illustrate several amplifier circuits further down. It doesn't look like you can directly drive the buffer chip with the sensor output.
Then why did I find a circuit where the phototransistor is directly connected to the buffer amplified?
Maybe there are other kinds of 74HCTxxx out there?
Is there a good octal amplifier for this purpose? I am building something that would use 8 channels. 8 sensors.
In the past, I made a revolution counter by attaching a phototransistor in place where pedometer pendulum with contacts goes. It worked! It counted the number of turns in the shaft.
This task of a bigger project would not involve a microcontroller.
What would I need to do to make individual optical sensors change state of individual flip flops?
I decided that it would be more economical to make my device in such way that the optical input changes state of a flip-flop (D trigger) every time there is a reflection.
What IC would you recommend for this individual flip-flopping?
In this case I don't need a counter that sums all the bits of data into a number. I want individual circuits to work like this: (see attachment)
You want indivual DQ flip flops, not a transparent latch.
You want each positive going edge from the optical sensor to invert the flipflop state?
Then you have to wire Q-bar to D, and route the optical sensor to the clock input. This means
you need 8 individual flipflops, the clocks cannot be shared.
I think that means 4 74HC74's are needed (they are dual DQ flip flops with schmitt-trigger clock
inputs).
Noone uses 74LS logic family for decades, 74HC is what you need.
You can run at any voltage from 2V to 6V with 74HC chips too, so they work with 3.3V
systems, not just 5V. And they are cheaper than 74xx and 74LSxx as they are not
antiques(!)
