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Topic: Is This a Sensible Way to Wire and Test My Sensors? (Multiple Perf Boards) (Read 50 times) previous topic - next topic


Hi all.

I would appreciate some general guidance here. I am wondering if the way I have layed my project out below is a weird way to do things? Is there a better way to do this?

It has certainly been time consuming, and as a beginner, I'm wondering if the way I arranged the "rails" is correct? I did test for connectivity with the buzzer on my multimeter, and things seemed to be in order for each individual board.  I laid things out this way in order to ensure good electrical connections and to be able to power all the LED's on one set of rails, and all the phototransistors on the opposite rails.  The breadboard was just too frustrating to deal with. (Having things moving around all the time while I take analog to digital readings)

In the picture below, you'll see a series of perf boards layed out in a vertical orientation.  They each have 2 circuits containing Omron EE-SX1140 sensors soldered to them, which I'm feeding into the analog inputs of my Sparkfun Arduino Pro Mini (8 analog inputs).

The EE-SX1140 is composed an IR LED and a IR phototransistor (a photodiode connected to a BJT).  
It normally is used to detect whether or not something is present between the slot. A binary "yes" or "no" is registered. However, I'm repurposing it slightly to give me an analog readout. With my circuit when an semi transparent item is placed in between the slot, the phototransistor outputs a voltage proportionate to the amount of light transmitted across the slot.

I eventually want to use my Sparkfun Arduino Pro Mini to test how consistent the readings are for my translucent plastic reference item of choice. I'm looking to obtain some fairly comprehensive data to prove that these sensors are worth using.  

I can only fit 2 sensor circuits comfortably on each small perf board.  I thought about buying a long narrow perfboard from Digikey, but they cost over $40, and I kind of like the "modularity" of this system

The perf boards are attached to a piece of lasercut plexiglass using aluminum hex standoffs.

My specific question was if it's wise to have these modular perf boards and if you see any flaws with the "rails" layout?  I actually had some trouble obtaining readings late tonight and plan on re-trying yesterday.  May have something to do with the way I arranged the "common ground" wires.  


Also, can someone tell me how to embed an image in this forum? Hate having to ask users to click a link below that does not even include a thumbnail preview...


In order to embed the image you first have to attach it (as you have done) and save the post.

Once the post is saved copy the image URL (right click "copy link location"or whatever your browser calls it).

The edit your original post (use the 'more' dropdown and choose 'modify') and insert the image URL- voila!

One wonders why the forum software doesn't do this automatically...

As for your wiring- you appear to have positive and ground rails both sides of the board (and quite close).  I maybe would have just had one set- positive at the top and ground at the bottom to avoid accidental short circuits.  But there is no "right"way just whatever works for you.

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