Using a LM301 OP-AMP as a crystal accosilator.

[Scott Wiper]

Sorry If I missed spelled the top part. I need to know how you can use a
LM301 OP-AMP or a SHMITT trigger IC to 10MHZ out from a tin can crystal.
Also I need to know if this can be done at +5VDC or do you have to go to
+12VDC? Another option I am also trying to figure out is to use a 4MHZ
resonator that has to out pins and a ground pin in the center.

I will use binary ripple counters to divide this down to 60HZ for a home
made digital clock I am working on. The A.C. coming from the wall will be
the primary clocking source but when it loses power I would like the
crystal circuit to take over and continue to clock the project. I would like
to keep this "cheap and dirty" if possible.

A hand drawn schamtic would help with this problem.

--
My Cat Tigger says every morning...
Before my morning coffee I
might as well be a DOG!
http://www.travel-net.com/~swiper

 

[Jean-Michel Friedt]

Sorry If I missed spelled the top part. I need to know how you can use a
LM301 OP-AMP or a SHMITT trigger IC to 10MHZ out from a tin can crystal.

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 http://friedtj.free.fr/chua/08520429.pdf (forget about the text which
is in French, just look at the circuit and the reference related to it
citing AoE).

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.

Also I need to know if this can be done at +5VDC or do you have to go to
+12VDC? Another option I am also trying to figure out is to use a 4MHZ
resonator that has to out pins and a ground pin in the center.

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).

to keep this "cheap and dirty" if possible.

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

 

[Jim Thompson]

On Thu, 7 Aug 2003 07:00:38 -0400, "Scott Wiper"
<swiper@travel-net.com> wrote:

Sorry If I missed spelled the top part. I need to know how you can use a
LM301 OP-AMP or a SHMITT trigger IC to 10MHZ out from a tin can crystal.
Also I need to know if this can be done at +5VDC or do you have to go to
+12VDC? Another option I am also trying to figure out is to use a 4MHZ
resonator that has to out pins and a ground pin in the center.

I will use binary ripple counters to divide this down to 60HZ for a home
made digital clock I am working on. The A.C. coming from the wall will be
the primary clocking source but when it loses power I would like the
crystal circuit to take over and continue to clock the project. I would like
to keep this "cheap and dirty" if possible.

A hand drawn schamtic would help with this problem.

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

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| Jim-T@analog_innovations.com Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

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Lack of mental capacity?

 

[Bill Bowden]

"Scott Wiper" <swiper@travel-net.com> wrote in message news:<bjqYa.53427$PD3.4553192@nnrp1.uunet.ca>...

Sorry If I missed spelled the top part. I need to know how you can use a
LM301 OP-AMP or a SHMITT trigger IC to 10MHZ out from a tin can crystal.
Also I need to know if this can be done at +5VDC or do you have to go to
+12VDC? Another option I am also trying to figure out is to use a 4MHZ
resonator that has to out pins and a ground pin in the center.

I will use binary ripple counters to divide this down to 60HZ for a home
made digital clock I am working on. The A.C. coming from the wall will be
the primary clocking source but when it loses power I would like the
crystal circuit to take over and continue to clock the project. I would like
to keep this "cheap and dirty" if possible.

A hand drawn schamtic would help with this problem.

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:

http://ourworld.compuserve.com/homepages/Bill_Bowden/dclock.htm

-Bill