Using a LM301 OP-AMP as a crystal accosilator.

I'm not familiar with the LM301, but I just finished writing a tutorial on the quartz crystal microbalance in which I use a video op-amp (AD811) for such a purpose. You can find the circuit on p.7 of the document available at

For the schmitt trigger ... just take an inverter gate (74HCT04), connect the quartz between the input/output of an inverter, stick two capacitors between the quartz leads and ground and that should oscillate. You have to play with the value of the capacitor (in the tens of pF range) but the actual value is not critical. All this is well explained in the ARRL Handbook.

From my experience with the AD811 i had to limit myself to 5 V supply or the opamp would overheat. The CMOS inverter can be power supplied with anything from 3 V to 7 V, but chances are that at higher voltages you will jump on an overtone, so try to set the supply voltage as low as possible (for reliable operation).

The CMOS inverter is about as cheap and dirty as you can get (but not dirty enough that there is not one in the Ariane rocket ...).

Jean-Michel

No. An LM301 has insufficient bandwidth. A Schmitt trigger inverter generally won't self-start. Use a 74HCU04, unbuffered inverter.

...Jim Thompson

The easy way is to use a 32.768 KHz crystal from an old watch or quartz clock and divide it down to 1 second with a 15 stage counter. There is an example schematic using the 4020 14 stage counter and one additional D flip flop at:

-Bill