Sunday, November 23, 2008

YSM35B Extending the Pancake Motor Wires

This is the sixth in the series of instructions on how to build the YSM35B Vibrating 35mm DOF Adapter. In the last part we adjusted the distance of the ground glass to achieve sharp infinity focus. A test of the static mode showed the grain and dust that could stick to the ground glass. We now begin to assemble the electronics.

Extending the Pancake Motor Wiring

The parts and tools you will need for this portion are:

Scrap CAT5E cable or some solid core wire
Vibrating Motor (Coin/Pancake-style)
Soldering Iron/Gun
Solder Wire
Glue gun with glue sticks

I have no training in electronics. But I asked some people who did and picked up how to use a soldering gun. If this is your first time you might want to practice on some scrap wire first.

Stripping the insulation
We want to extend the wiring of the pancake motor so I picked some solid core from a splice of CAT5E cable. You can use telephone wire but this tends to be thin. Solid core is rigid and easier to strip without destroying it.

My technique is to use a nail clipper. Apply light pressure to pinch the insulation then twist the wire around. It doesn't have to go all the way through. Pull on the insulation and it is now stripped. Do not worry too much if you take out too much. Just make sure you have enough to contact with the wires on the pancake. Do this to the other end of the wire as well. Prepare two.

How to Solder
The basic soldering iron is a device that will produce heat. It should be enough to melt the solder wire. At the right temperature the wire changes from a solid to a liquid. Once that heat is removed it cools quickly and turns back into a solid.

To prepare the soldering iron make sure the tip is clean. I like to use sandpaper to scrape off excess carbon from previous uses. Plug in to the wall socket and allow to heat for a few minutes. Be careful not to touch anything but the handle. Once heated it is easiest to touch the solder to the tip and allow it to bead. Rest the solder gun on something solid and non-flammable.

Two wires will stick easily if they are tinned. Tinning is applying a coat of solder on a wire. This way just touching the two wires together with the iron on one side would join them.

You will need both hands to the final join. With the iron rest at an angle, touch both wires together onto the heated tip. When you see the solder bead or melt pull both wires away. The solder should quickly cool. When hot the solder looks silver. Cold its a dull grey.

If you take too long you might melt some insulation. And you might notice heat along the wires. This is okay for the most part.

Insulating the Solder
Its possible to short the motor if the two exposed solder joins come into contact. To prevent this we could use various types of insulation from electrical tape, to heat shrink tubing and hot glue. In the YSM35A I found that electrical tape tends to lose adhesion over time. Heat shrink is hard to shrink significantly enough. So this time around I tried hot glue. It is non conductive and malleable.

So I apply a coating of hot glue around the two solder joins. Then I glue both together. The two joins are separated by the layer of glue.

Testing your wiring
Now its time to see if it works. Take a AA battery and touch the "red" wire to positive and "blue/black" wire to negative. The vibrating motor will work in either way but this is the convention.

What's next?
Next we'll create a control box with a battery holder, speed control, and power switch.

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