Wrap excess wire around magnet supports to provide strain relieve and protect your soldered joints.

LED Bridge Lamp Electronics

For me, building the electronics for the LED Bridge Lamp was one of the most fun parts of the project.  It was an opportunity to build upon the skills I learned from earlier/simpler projects and create a really fun display/art project.

Circuit Design

The first step was figuring out the details of the circuit. To do this breadboarded the circuit and worked out the details. The resistors in the circuit are to protect the first LEDs on the strip data lines and the large capacitors help smooth out the power from the power supply.

Testing the bridge section LEDs
Testing the bridge section LEDs

 

You can find the Fritzing generated circuit diagram here:

Circuit Diagram for my LED Bridge Lamp
Circuit Diagram for my LED Bridge Lamp

Here’s what I used to build the electronics for this project:

Parts List (Quantities reflect sets/packages from the related links):

Assembly 

With the design in hand, the next step was assemble the bases and solder everything.  For the purposes of differentiating them in a succinct way I will refer to the base with the Adafruit Feather Huzzah Micro-controller in it as the ‘Smart’ base and I will refer to the base that only has power inject in it as the ‘Dummy’ base.

Here you can see a full assembled base complete with the 90lb strength magnets that will keep the bridge perched in place over my cubicle walls at work. (You can learn more about building this base in my earlier post here)

90lb Strength Magnets integrated into the base
90lb Strength Magnets integrated into the base

For the panel mount connectors I made sure they fit into the printed holes in the side of the base. I put one of the male connectors into the panel mount connector to keep everything lined up as I soldered (the plastic in there melts easily). I also put heat shrink tubing over the connectors.

Use heat shrink tubing to protect the soldered connections. TIP: Put a mail connector in the female connector when soldering to keep the plastic from deforming.
Use heat shrink tubing to protect the soldered connections. TIP: Put a mail connector in the female connector when soldering to keep the plastic from deforming.

 

The “Smart” Base

Next up was translating the bread-boarded circuit to a perma-proto board. I used female headers so I could remove/replace/upgrade the micro-controller in the future if  wanted to.

Adafruit Huzzah 8266 in headers on soldered half size permanently-proto board
Adafruit Huzzah 8266 in headers on soldered half size permanently-proto board

The circuit itself is pretty simple/straightforward.

Underside of assembled half size permanent-proto board which hosts the Huzzah
Underside of assembled half size permanent-proto board which hosts the Huzzah

With the panel mount connection inserted through the top curved section of the base and secured with its included nut, I soldered its wire to the permanent-proto board. I used about a foot of wire so I had plenty of space to work with when the setup is semi-assembled as shown below.

Soldering the power cable to the perm-proto board AFTER it was inserted through the bridge lamp base.
Soldering the power cable to the perm-proto board AFTER it was inserted through the bridge lamp base.

Next up I secured the permanent-proto board to the electronics tray/base. I wrapped the excess wire that around the magnet supports to provide strain relief to the soldered joints. The additional wires below are the wires that least to JST connectors which will provide a modular linking to the LED strips in the bridge.

Wrap excess wire around magnet supports to provide strain relieve and protect your soldered joints.
Wrap excess wire around magnet supports to provide strain relieve and protect your soldered joints.

With everything assembled it should look nice and clean and orderly as shown below:

Underside of completed 'smart' base
Underside of completed ‘smart’ base

For the USB cable I drilled a whole in the side of the riser block with a brad point drill bit and inserted the USB cable. I wrapped that cable around the magnet supports to provide strain relief here as well.

Underside of completed 'smart' base with USB cable routed
Underside of completed ‘smart’ base with USB cable routed]

The completed based is just about done.

Assembled base section (close up)
Assembled base section (close up)

I also inserted M4 Button Top machine screws to secure the top and bottom sections of the base. They self tap a bit into the plastic and hold well. They also allow me to disassemble the setup easily from the outside.

Button head machine screws used to connect top/curved have of base to the electronics tray
Button head machine screws used to connect top/curved have of base to the electronics tray

The “Dummy” Base

The “Dummy” base is largely the same procedure as the “Smart” base with the exception being that this side does not have a micro-controller — it simply injects power at the mid point of the LED light strips — without this it would look like the LED strips brown out about midway across the bridge.  The large capacitors used in this project are to protect the LED strips and smooth out the power they receive.

Dummy base with power injection. Leave extra wire so you can remove the curved section as needed.
Dummy base with power injection. Leave extra wire so you can remove the curved section as needed.

I followed the same methods of assembly, soldering, cable wrapping etc.

Underside of completed 'Dummy' base
Underside of completed ‘Dummy’ base

Cabling

Between each base and the bridge assembly and between each of the 3 bridge sections I used JST connectors for power and data (See photo below). I would build each male and female section, test the connections and then solder them into place.

JST connectors and crimper
JST connectors and crimper

I liked the idea of everything being modular but in hindsight almost feel it was more trouble than it was worth. I found myself still having to debug a bunch of these wire connections as the JSTs seem to have  a little play in the connections so if the wires are bent up — say when trying to cram those connections into the bridge superstructure sometimes the connection would open up.

When soldering my larger panavise was helpful in holding things in place so I could solder the JST connected wires to the LED strips.

Larger pane-vise was helpful in holding the assembly when I had to solder on the wires connected to the JST connectors
Larger pane-vise was helpful in holding the assembly when I had to solder on the wires connected to the JST connectors

Shown below is a completed base with the JST connectors showing.

Assembled base section with taller riser and micro controller. Note the USB cable coming out through a drilled hole in the riser.
Assembled base section with taller riser and micro controller. Note the USB cable coming out through a drilled hole in the riser.

Testing

With everything in place it was time to test the full circuit. This is where the extra wire on the JST cabling in the base came in handy. I could lay the bridge out on my dining room table and test the circuit and work out the software. Also it was nerdy fun to be effectively sitting inside this light ring in a dark room.

  • Testing the bridge flat on the table
    Testing the bridge flat on the table

    Once I got everything working it was time to pack it up and bring it to the office. Given the headaches with the JST connectors I brought the bridge section in as 1 completed piece rather than breaking it down into segments and testing all the connections again.  It filled the whole bed of my pickup truck but survived the ride.

Completed bridge assembly in the back of my pickup truck ready for delivery
Completed bridge assembly in the back of my pickup truck ready for delivery

The next post in this series will be related to the software.

You can navigate back to the Enhanced LED Bridge Lamp Summary here. 

Take care,
-Bill Rainford
@TinWhiskerzBlog
@TheRainford

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