September 4th: Metalworking with my Nephew...

Candy's family is in town for her Mother's big surprise birthday party. My nephew hung out in the garage today and learned how to use the plasma cutter. Below are pics of him wire-brushing the metal with the die grinder getting it ready for tomorrow's lesson in welding. He didn't have long sleeves or pants, so he's wearing one of my shirts, my tall tube socks and an improvised towel apron. I really need to get some leather aprons for myself and guests...

I REALLY need a tall welding table..

I purposely wanted to do this "overhead" weld to see how it came out. I know I should have flipped the material over...

We used the drill press to add two mounting holes.

Ta Da!

I loved the HAZ (heat affected zone) discoloration on the insides of the letters, makes a really cool effect.

Overall, not bad, probably 3 hours start to finish, with lots of explanation and practicing without actually cutting or welding. He did GREAT for his first time, and some of my welds looked better too - practice helps!

September 3rd: First big welding project is complete!

The family worked together to make a planter for my mother-in-law, Elaine. My boys call her "Nana", so we personalized the planter with the new plasma cutter.

We made an upright "trellis" out of steel square tube, 1/4" plate and some cut mounting hooks from IKEA.

Primed the galvanized metal, cleaned the bare steel, and then painted the whole thing...

If you are paying attention, you are wondering - "what is that little yellow box next to the planter?" - Great question! :)

After we had "NANA" cut in the side of the planter, I thought...OOOOH...why not BACKLIGHT it so that at night you see this...

Back at Home Depot, I grabbed a 3-LED solar landscape light and then brought it home to disassemble. That little yellow box is the "light box" which holds the LEDs and has the attached solar panel.

The final product (with a Jasmine plant installed) looks like this...and at night, "NANA" is visible through the side just like the pic above...

Here's another shot where you can see the light...

It also has some ACCESSORIES! First a bright purple watering can (she loves purple)...

And I found this idea online, so the boys & I made one from spoons and a ladle we purchased at IKEA.

The family is very proud of how it turned out, everyone had a chance to help in some part of the construction, and we think she will LOVE it. Her cake is also a planter / flower theme, so it all works together!

Below are some pictures of the light box construction. It was great sheet metal fabrication practice for me...

This is the light box in the middle of welding the curved edges. The light box started as a flat sheet of 22 gauge sheet metal from Home Depot. Adam & I made a template with cardboard, then used the plasma cutter to cut it out, then the vise for bending the edges, then tack welded & grinded the seams...

This is the point where I really got excited - the edges came out GREAT and I never thought I could build something like this...

You can see some of the little holes...more welding & grinding required!

Once it was painted, I moved to the workbench for assembly...

I drilled the big hole in the back after painting, which meant another prep / paint / wait cycle...Next time I build something like this I'll fine sand it after priming and between top coats. I experimented a bit with it on this one and that section came out ultra-smooth!

The remaining parts from the sacrificial landscape light. I picked this one due to 3 LED brightness, a BIG solar cell and a lithium battery. I was surprised to see 5 wires going to the LEDs. The charging circuit is down on the board with the LEDs.

Below was a test fit with the new aluminum reflector. Blue tape is so versatile! Here it is attaching the board AND insulating it from the aluminum reflector :)

I used ribbon cable to extend the wires, and heat-shrinked everything :) I also used hot glue to insulate the back of the circuit board AND to attach the board to the reflector.

I bent a piece of clear polystyrene and siliconed it to the the front of the box to both waterproof and diffuse the light. I did not trust my welded seams to be waterproof so I siliconed all the edges :) Messy, but should be watertight.

In the front view of the final light box, you can see the aluminum reflector (it is curved...looked cool, don't know if it really helps...) and the LED / charging circuit and wires hot glued to the reflector...

Another benefit of this light is that the battery is replaceable and in the bottom of the solar cell assembly, so I don't have to open the light box...

This was a GREAT project. We plasma cut, bent metal, welded metal, grinded (ground?!), soldered, hot glued, sanded, wire brushed, primed, painted, heat formed (polystyrene), epoxied (trellis to pot), glued (pvc) and siliconed. 

August 16th: Arduino Tips...

A few quick tips that I wish I'd learned sooner.

1) You can attach a button / switch to an arduino without an external resistor. You connect one side of the button to ground, the other to the digital input. Set the pinMode to input, then turn on the internal pullup resistor using the digitalWrite function. I like using defines for my pin numbers at the top of my file.


  #define SWITCH1         5

  pinMode(SWITCH1, INPUT);
  digitalWrite(SWITCH1, HIGH); //turn on pullup

Later, when you need to read the switch, just use digitalRead and test for LOW.

 if (digitalRead(SWITCH1==LOW))

    {

      //do something

    }

This method simplifies your circuit AND keeps you from running power to all your switches reducing the possibility of shorting your power supply.

 

2) You can use the analog input pins A0-A5 as digital inputs! Just number them 14-19 and use them for standard digital I/O.

Using the above code, you would simply define SWITCH1 as 14 and connect the switch to pin A0 on the arduino...

  #define SWITCH1         14 //A0

  pinMode(SWITCH1, INPUT);

  digitalWrite(SWITCH1, HIGH); //turn on pullup

 

Little tips go a long way to maximizing productivity and hardware capability...enjoy!

August 15th: Hockey Season!

My good friend Luis is a bit of a Hockey nut. He not only watches hockey (He's a Rangers fan...), he pre-plays the games for the Rangers on his xbox with his brother. He also has an "original 6" table hockey game with a custom cover made by his family.

I don't think that is the exact model, but you get the idea :)

A few years ago, I was scrapping an old air hockey table and Luis took  the scoring system and modified his table hockey game to use the scoring mechanism.

He cut out the goal area so the puck could go down into custom lexan fixtures that hold the air hockey table scoring switches.

These velcro to the bottom of the table hockey game. They are removable so the table can be transported and still lay flat.

Last year when I got into messing with arduinos, we were kicking around the idea of making a custom scoreboard for the table that would use the Adafruit WaveShield to play hockey arena sounds & music.

At the time I wrote out some basic plans, but focused on finishing my son's "control panel" and finishing my MBA.

A month or so ago, I found the NCR VFDs at Skycraft and this triggered the scoreboard idea again. I made a shopping list for Luis, he ordered the parts and off we went.

The project has come together quickly. We had an afternoon where we soldered up the WaveShield and modded his VFD for TTL serial. I have worked on the code a few hours here & there, and Luis has been working on getting the components mounted. Since I didn't have my shiny new welder this week (thanks UPS - once again you screw with my happiness!) I decided to really get moving on this project. I wrote most of the code logic yesterday and today we got the prototype case finished up. 

Here is the VFD mounted in the case. We had a little mix-up on the VFD dimensions, so the prototype has a little extra view of the VFD :)

Side view showing the lighted power button and power jack

A shot of the inside wiring - Arduino and WaveShield on the bottom right, VFD is the big board, buttons up top. We've since added an RJ45 "magic jack" with a SparkFun breakout board at the bottom. It will be the connection to the table switches and LEDs. The green wire coming up the middle of the VFD board is the TTL mod. 

  

.  So, how will this thing look in action?? Here it is next to the table. The wires on the side of the table are where the scoring / intermission LEDs will be placed.

And more action shots...

Intro screen...music will be playing...

Select the home team. The middle button is "next" and the right button is "ok" in this mode.

We are making the periods 20 mins like "real" hockey, but then making the clock run down faster. Not sure it will stay this way, but makes life much easier for testing because I can set the scale at a crazy high number and get periods that are a few seconds long :)

In game shot... (scoring switches not connected yet...) During the game, the right button is "play / pause". After a goal, the timer automatically pauses and then a button is hit to resume gameplay (after a short timer to allow the person hitting the button to "ready" themselves...)

I'm really excited to get the sound / music code integrated and get this thing connected to the table. I might even have to learn how to play!

August 8th: Let's WELD!

I've backed off the electronics design & testing for the last two weeks. I was in deep and needed a break. I've switched gears to disassembly on the Firebird. I've gone MUCH farther than I intended (as usual) and will likely keep going.

One of the next major projects on the Firebird is rectifying the swiss cheese firewall. The no-longer needed hole for the factory AC is a mess. It had been hacked in the past and the cover plate was gooped on. It wasn't panel bonded or epoxied, it was soft, pliable black goop. Yuck.

I want to do it right, so I've ordered a filler panel from Detroit Speed (this is a common modification since aftermarket AC doesn't go through the firewall) and now I'm learning to weld. Sure, I could use 3M panel bond, but what fun is that?!

Here are two pics of the major firewall hole...

I also have some transmission tunnel cleanup work to do. I've started it with the cheap Harbor Freight flux core box, but I'll wait for the real MIG box to show up before finishing it.

This is the "cover" the previous owner made to patch up the transmission tunnel.

He not only hacked the tunnel, he left a ridiculous amount of holes...

Here is the "after" shot from me filling (and grinding, and filling and grinding...) the holes...

And the new "cover" made from 16 gauge steel...

As usual, I'm trying to get the boys engaged in the process. I don't think they understand yet just how cool welding is. My little guy went shopping for supplies last night AND he watched the GMAW (MIG) WIRE FEED video I purchased.

Here he is, ready for action!

When I took him to the Lincoln Electric site to show him the welder I ordered, he saw that they make an Iron Man welding helmet. I didn't have much choice on the design of my new helmet after that. I suspect I'll have to fight him for it :)

For those of you that are into such things - I've ordered a Lincoln Weld Pak 180, which is a 220v MIG welder. I also ordered the spool gun for welding aluminum and a cart. I will be purchasing an Argon / CO2 mix cylinder for welding steel and a pure Argon cylinder for welding aluminum. Yes, I know TIG is the fancy way to weld aluminum, but this was an easier (and cheaper) way to get started. I need to prioritize my ability to easily weld old steel bodywork and MIG is the way to go for bodywork. If I get decent at this, I'll try TIG in the future.

I also think it will be MUCH easier to teach the boys MIG.

Wish me luck!

July 24th: General Update

Last weekend I received the BTS550 and BTS555 High Side Switches from Infineon. As usual, my comprehension of the datasheet prior to ordering didn't really prepare me for what I ordered. I missed that these are NOT microcontroller friendly devices. When they are OFF, the voltage at the microcontroller input is the car  power voltage, so thats 12+ volts. Good thing I was using the Rugged Circuits Gator+ and not a standard Arduino, or I would have taken out some pins. The BTS could handle more current, but still not enough to drive the big fans with just one device and a smallish heatsink.

That evening of tinkering was a pretty big setback and I ended up pretty discouraged. If only they made the IPS6011 with a higher current capability. Sigh. I took the rest of the weekend off from electronics and continued the garage cleaning. It was VERY productive and I'm almost done.

During the week, I decided to let the project sit in the background, maybe my motivation would return or I'd have some epiphany.

A few things did come to mind:
1) I should be able to gang the IPS6011 for higher current capability. I emailed International Rectifier to see if they had any design considerations for ganging them.

UPDATE - response from IR (on SUNDAY MORNING!!)


Because IPS parts have HEXFET outputs, it may appear possible to parallel them., because as you know the Rds(on) of MOSFETS has a positive temperature coefficient which aides current sharing in parallel part situations. However, with IPS parts there is a practical difficulty as a result of the built-in over current and thermal overload protections. These protections are not built-in to discrete MOSFETS. There will be small differences in the actual Rds(on), the over-current and thermal trip points due to normal parametric spreads in these characteristics between a number of IPS parts. Which means that in an overload situation one part will be inclined to shutdown before the others. With IPS parts the over current protection is reset when the input signal is cycled from on to off to on and over-temperature is automatically reset when the junction temperature cools by around 7*C. With one of the parallel parts shutdown, the total load current will be shared with fewer devices which in turn will carry an increase in current and tend to shutdown in a chain reaction. As the input signal is cycled, every part will try and turn on again. If the input cycling is automatically repetitive with the current overload condition still present, the junction temperatures will tend to rise progressively until the first device shuts down due to over-temperature. Eventually all devices will shut down initially due to over current and ultimately due to over-temperature. The time for all parts to shutdown will be a function of the magnitude of the over-current, the individual device characteristics and the thermal conditions of the application with respect to heat sink ratings and device local ambient temperatures.

We do have many customers using it in parallel.In a parallel configuration of devcies, the major consideration is effective current sharing.Also, as these devices operate with current sense feedback, extensive circuit testing would 
be needed to ensure proper operation. We do not have reference designs / data for such an
application. However, a point to note is that during circuit turn-on, for a slowly ramping 
current (such as for an inductive load), the paralleling works better. For fast ramping loads
paralleling may be more difficult. You would also have to ensure proper feedback for each of 
the devices in parallel.

2) I've been testing with my WORST-CASE load - a GIANT cooling fan. I can always relay these big inductive loads and go on with life. I need to move forward with my plan to measure each load in the car to figure out if a single IPS6011 circuit for each will suffice. With a small heat sink, I proved them for an 18 amp inductive load. With a larger heat sink and a non-inductive load, I may be able to push higher.

3) Big mosfets aren't usually shoved in little cases - in fact, the cases themselves are typically the heatsink - car audio amplifiers and car ECM / ABS modules come to mind - the cases for most car modules are thick aluminum and many have fins molded onto the case. I may hit a "u-pull it" junkyard for some case options...

Last night I finished pulling  the factory harness. I found even more crimp connectors, taped connections and wires to nowhere. The seats are out, the carpet is almost out. I need to pull a few more things, then get started putting Humpty Dumpty back together again. Once again I'm having that "why did I go this far" feeling. I sure like doing this to myself... I need to either get this wiring harness project moving or just order one to move on - but that sure wouldn't be as much fun...or frustration :)