Some toys should be seen, but not heard! My 2.5 year old nephew is big on firefighters right now, so I found this great helmet for him that has a cool flashing light at the front. However, it also has a siren, and both the light and siren are controlled by the same switch. If I want to ever be able to set foot in their house again, I need to do something about that last part...
For this project, you'll need the toy you want to modify, a switch, a soldering iron, some solder, and a pair of wirecutters (or a knife, if you don't have any handy). The soldering for this project it super, super simple. If you don't have any experience, this would be a great beginner's project!
I bought this toy online, sight unseen. It had great reviews, but someone noted how much better the toy would be if there was some way to disable the siren! There's a simple technique that I've been wanting to share on Instructables for a while, and this seemed like the perfect opportunity.
Adding a switch to a piece of electronics is often very simple. I've used this technique many times, to save batteries, add functionality, and in this case, preserve sanity! Here's a very, very basic layout of how many battery operated items work: a battery is connected up to a whirlygig. As long as they're connected, they whirlygig will continue to whirl (or is it gig, I forget). It could be flashing lights, a motor, some kind of noise making device, doesn't matter. As long as the battery is connected and giving the device power, it'll keep doing its thing.
What a switch does is disconnect the battery from the whirlygig. When the switch is "open", the battery is disconnected, and nothing happens. When you "close" the switch, it's like the switch isn't even there, and the batter and whirlygig are once more reunited. You can make a simple switch just by taking a certain wire in a device (one that's connected to the battery or whirlygig), and cutting it. Try it now!* When the wire's cut, the device stops working. Put the two ends of the wire back together, and it works again. That's a switch!
When I ordered the hat online, I had no specific knowledge of what the electronics inside looked like. But adding a switch is so simple that I was fairly certain I would be able to get it to work, and sure enough it was a piece of cake. I think this whole project took me somewhere around 15-20 minutes. So let's take a look at what's inside the hat.
Basically we've got the batteries, a switch, some lights, and the siren. They're all connected through a circuit board, but we really don't have to worry about that. Since we want to put a switch on the speaker for the siren, that's all we're going to focus on. All we need to do is find a wire that goes to the speaker, and insert our switch. That white wire looks like a great candidate, but there's only one way to find out. Cut it!
Do it! If it doesn't work, we can always stick it back together with some solder later. Once it's cut, turn the toy back on. The lights should blink, but the siren will be blissfully silent. Take a second to strip the ends of the wires, since we'll be soldering them to our switch later.
If your goal was to just silence the siren, then congrats, you're done! However, I wanted to get fancy with it. There are all kinds of switches we could add at this point. We could add one that looked just like the existing switch, or we could add a push-button switch, or a toggle, or whatever your electronics shop has on hand. I wanted to add a bit of "magic" to the toy, so I added a reed switch. It's a really cool switch that closes once you put a magnet near it. Whatever kind of switch you go with, it really doesn't matter, the process is going to be the same: find the wire that goes to the part of the toy you want to switch, cut the wire, solder in the switch, and voila!
This part's pretty straight forward. You don't need a lot of soldering experience, but you will need a soldering iron. Make sure the two wires from the toy are stripped, and that the two wires from the switch are stripped. Take one wire from the toy and one from the switch, twist them together, add a little bit of solder, and then do the same for the other two wires. Here's the great thing, it doesn't matter which wire goes with with, just make sure you have one from the toy and one from the switch, then solder them together. I added a bit of heatshrink tubing to cover the ends. You could use electrical tape, you just don't want the soldered parts coming into contact with anything.
For a finishing touch, I'll probably paint the "key" magnet red, then attach some velcro to it and the helmet. Plus, when the key isn't in use (outdoors only!), it can be attached to the refrigerator for easy storage (above the reach of tiny hands). Hope you've enjoyed this write-up, and let me know if this has inspired you to make any similar modifications. Good luck!