Coupling optical sensors to solid state relays with octal buffer amplifier

Hello. I would like to couple 8 optical sensors: TCRT5000L-TCRT5000 Reflective Optical Sensor

official description

to eight Solid State Relays that are activated by a voltage of 3.5 to 5 volts.

Can I use HCT244 to do that?

This is where I got the idea and the circuit diagram

What would my wiring look like?

Do I need to add any resistors/capacitors that are not depicted on this diagram?

I connect phototransistor outputs to 1A and 2A?

1Y and 2Y are the outputs for everything that can be directly wired to the inputs of a Solid State Relay?

Where do 1G and 2G connect to?

Thank You.

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.

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.

Hi, To quote from the site of your schematic.

The following circuit diagram is [u]what I want to achieve[/u] and so I need to work out the values of the resistors to use..

It doesn't say he achieved it.

In fact if you look at the document that the site cited, there are suggested circuits with transistor and op-amp interfaces.

Tom... :)

VT91: Then why did I find a circuit where the phototransistor is directly connected to the buffer amplified?

That drawing might be the graphical equivalent of pseudo code. It may work. However, if it doesn't, that's the first place I'd look at more closely.

Thank you.

This looks like a real working circuit with a discription.

This also looks ligitimate.

My last question would be:

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)

I found this page about this flipflop array that I may use.
http://www2.hawaii.edu/~jrand/ElectricalEngineering/5%20-%20Flip%20Flops/

If I use 74HCT574 Octal D Flip-Flop , do I enable all D flip-flops (that work individually) by tying the CP pin to high?

I want to use some octal IC to create 8 individual latched outputs, without using the clock. Is that possible?

I am looking for something like 74LS373 ?

VT91: What would I need to do to make individual optical sensors change state of individual flip flops?

Wire each sensor to the clock input of a 7473 or 7474 flip-flop. Consult the respective datasheets for the toggle configuration.

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(!)