Making High Impedance Headphones
With less than 5 bucks (better known as $5 USD) you can make a high-impedance headphones for your homemade crystal radio. (11/27/2007)
Nick asked me if my homemade high-fidelity speaker can work as high-impedance speaker for his crystal radio. Unfortunately, the answer is No. It doesn't work. To increase the resistance of the speaker we need 38 or 40 AWG wire and hundreds of loops. That is too much trouble for something simple.
We can make our hi-impedance earphones with less than 5 bucks using piezoelectric speakers. Here is what we need:
If you don't have those items, is a good idea to use "made in china" products as it is just junk. I will show you why later.
First, we take the broken watch and open it.
What? this one is not a broken one?
Ok, now it is broken. We can use it for our project. (Kids: Don't try this at home)
Open the watch. You may need a really small screwdriver. You can buy one at the Dollar stores just for one dollar. ($1 USD)
Pay attention to the message at the back of the clock. It says "MADE IN CHINA", "STAINLESS STEEL" and "WATER RESISTANT". Do you believe that? I never believe anything from Chinese products unless a good brand guarantee it.
After the watch is open, we can see the piezoelectric. It acts like a speaker on our watch.
If you pay attention to the watch, you will notice there is no seal at all. Anyone can explain me how a "Water resistant" watch doesn't have any seal? Of course! It's made in china!
Whatever, let's go to the point.
Now we can take apart the headphones.
Let's remove the speakers located inside...
Remove the wires... careful when using the iron.
By the way: Always know how to use your tools. Wear eye protection all the times when doing or making projects. I know a moron that wanted to save $60 dollars replacing the refrigerator handle by himself. He didn't know how to do it, the handle wasn't properly fixed and it fell on his eye. He lost an eye and sued the company that makes the refrigerator.
Be safe guys.
Solder the wires in the piezoelectric. Be careful not to damage the white area.
Glue the piezoelectric in the headset...
... and close it. Now you have your own high-impedance headphones for your crystal radio project.
Even if you don't want to make your headphones or you don't want to make your crystal radio, you can have fun with the piezoelectric! It basically is a tweeter and have some interesting applications.
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