crystal quartz and NAND gates.

[Kz9]

Hello,

I have a crystal quartz 3.57945 MHZ and a HD74LS00P Quadruple NAND gates, with 2 70pF variable capacitors & bunch of resistors.

I want to desgin a sqaure wave oscillator using these components, but I don't know how, I've tried the pierce oscillator desgin...but I can't get it to work.

Any suggestions or circuit diagram that can help me, please.

Kz9.

 

[FvM]

Classical TTL crystal oscillator circuits look like below (I've used them long time ago):

 

[Kz9]

It worked, thanks man

If am not asking too much, can you please explain how does it work and why is it different from the pierce desgin, the one with inverter.

one thing also, I used 1.1k Ohm resistors instead of the 470's. cause I didn't have any.

thanks again.

 

[FvM]

The "pierce" circuit works well with CMOS inverters, that have a high input impedance and can use a high feedback resistor value, resulting in a comfortable low crystal load.
The two cascaded TTL inverter provides extra gain to compensate for the resistive load.

 

[invaforce]

1 megaohm + 10 pf