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what is the difference of the crystal 4 leads and 2 leads?

i want to make a simple AM transmitter, which is use a crystal with 4 leads. and i don't have crystal with 4 leads, i only have crystal with 2 leads, can i use crystal with 2 leads ?

jeff-o7 years ago
Ah, that is a different beast.  This circuit uses a crystal oscillator IC, which requires a power source.  Inside, there's a crystal and a small amplifier, which together produce a clock source (for digital electronics, etc).  So the four pins are power, ground, enable and output.

This is a very clever circuit that uses the audio input to modulate the power source of the crystal (or rather, the amplifier inside), thereby generating AM.

So no, you can't use a 2-pin crystal.  If you want to make it just like this circuit, you'll need the four-pin type.  However, if you do a bit more digging I'm sure you'll be able to find an AM transmitter that uses a 2-pin crystal like you've got - it'll just require a few more components.
Rendydevara (author)  jeff-o7 years ago
thanks...
jeff-o7 years ago
The two extra leads may be dummy leads that don't do anything; they're just there to support the IC.  What's the part number?  Can you find its datasheet?
Rendydevara (author)  jeff-o7 years ago
this is the link of picture
http://sci-toys.com/scitoys/scitoys/radio/fingers_1_mhz.jpg

and this is the project (Building a very simple AM voice transmitter)
http://sci-toys.com/scitoys/scitoys/radio/am_transmitter.html

I have not found it