Switch-Adapt Toys: a WolVol Fire Truck Made Accessible!

Toy adaptation opens up new avenues and customized solutions to allow children with limited motor abilities or developmental disabilities to interact with toys independently. In many cases, the children who require the adapted toys are unable to interact with most toys currently on the market, because they aren't able to effectively push, slide, or press the manufacturer's operating buttons.

This instructable guides you through the process of adapting a WolVol Fire Truck! There is a lot of sensory stimulation in this one! In this instance, we are adapting the toy by adding a mounted female mono jack into which the toy recipient can plug in the switch of their choice (whatever switch they are able to control and operate).

Step 1: Step 1: Wire Preparation and Jack Soldering

There are two types of mono jacks you may choose to add.

In our images here, we are adding a mounted jack, which will be mounted on the toy itself. See our instructable about Preparing a Mounted Mono Jack. You may instead opt for a female mono jack with a lead cable (not shown). See our instructable about Preparing a Mono Jack with a Lead Wire.

IMPORTANT: Make the wire extending from your jack about 7 inches long as it will need to extend about ¾ of the fire truck’s length

Solder the wires onto the jack. Make sure the wires are pre-tinned before soldering onto the jack. Trim off excess wiring/solder from the jack.

Step 2: Toy Assessment

Carefully remove the toy from packaging.

Toy Check

Lets first make sure that the toy works. Unscrew the battery compartment and put in 3 AA batteries. Test the toy! Go on and play with it.

Understanding Activation

Look to see how the truck is activated. This particular truck has a single slide switch (on/off) at the bottom of the truck chassis (in the rear) behind the battery compartment.
Single-switch operation makes toy adaptation easy, as it is clear how we can replicate the function exactly with an external switch. The question is whether we would easily be able to solder our jack in parallel with the switch. To answer this question, we must open up the toy.

Step 3: Toy Disassembly

Turn the fire truck upside down, and unscrew the screws that hold the chassis and the top together.

WARNING: There are 6 screws that hold the chassis and the top together on this truck. Two of those are embedded rather deep in the plastic and are not obvious. If you’re not careful, you can easily wear down the threading in the plastic of the toy. Please don’t try to pry the toy open before you’ve made sure to unscrew all 6 of the screws (positioned as shown in the picture).

This toy is SENSITIVE. When you separate the bottom chassis from the top, do so slowly.

Step 4: Plan the Wire Exit

We need a plan for where to bring the cable attached to the jack into the toy. Typically we choose an area of the toy that isn't crammed with switches and wires; otherwise, you risk interference with the toy operation.

For this toy, we will make a hole on the top panel near the back of the truck. See the pics.

IMPORTANT: Do not try to drill into the toy. The plastic is brittle and will break.

With a sharp object cut through the plastic, and make a small hole for the cable to pass through. You MUST start small, and incrementally enlarge the hole to make sure that it isn't too big. Check periodically until the cable slides through the hole snugly.
Smoothen the surfaces, and file away any extra plastic hanging out. Insert the cable attached to the jack through the hole made.

Step 5: Wire Soldering

We have two tasks in this step:

Determine where to solder the jack to the board
Insulate and ensure proper wiring (making sure not to short the wires as they are close, insert a piece of cardboard for separation)

Look at the truck chassis and identify the backboard of the red switch. You should see three terminals on that board. One is free, and two have red leads soldered to them. Those are the two terminals to which we will connect the leads extending from the female jack. Please see image.

There are two free wires (leads) extending from the free end of female jack cable. The two leads are interchangeable. We will solder one of the wires to one of the terminals where red leads were soldered, and the other wire to the other terminal on the switch. Be sure to follow the safety instructions for soldering. After soldering both the original red wires, and the newly added jack wires are soldered on to the switch board.

IMPORTANT: DO NOT solder both free wires to the same terminal! If it helps, put a piece of cardboard or tape in between the terminals of the switch to avoid accidental soldering of a wire lead to both the terminals.

Carefully solder the leads on to the terminals.

Insulating: Place a piece of cardboard/thick paper between the terminals, as shown by the green paper fold in the above pic.

Test: with a switch plugged into the female jack, test the function of the toy (if you have to reinsert the batteries, please do so). The toy should activate as intended. If not, begin by checking that no wires had accidentally disconnected during the adaptation.

Step 6: Final Test Before Reassembly

Replace the top onto the bottom chassis slowly. Make sure no wires or tubings are pinched (especially the white tubing).

IMPORTANT: Check that there is no interference between wires, parts and anything that may have moved during your toy adaptation BEFORE you replace the screws.

Re-insert the batteries and test the function of your female jack, as well as the function of the toy (as it was before the adaptation).