Hi all.

I want to synchronize a laser pulse with an AC current (only about 1kHz)
source that unfortunately doesn't have a sync output. For the laser pulse
I need a good trigger signal, which up to now I have generated with an
oscilloscope that has a trigger output. But this signal is not very good,
probably it's 'cause the scope is not the best one.

So my question is, how do I generate a good trigger signal from a sine
signal with an amplitude about 10V-50V? It seems a pretty simple task, but
up to now I haven't found any device that does this job. Neither in
google, nor at the major test equipment suppliers. I am also not very good
at soldering, though if the circuit is very simple and the risk to screw
it is not very high I might try it.

Thanks for your help!
Alex

----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups
----= East and West-Coast Server Farms - Total Privacy via Encryption =----

On Mon, 29 Aug 2005 17:15:38 +0200, "Alexander Frey"
wrote:

Hi all.

I want to synchronize a laser pulse with an AC current (only about 1kHz)
source that unfortunately doesn't have a sync output. For the laser pulse
I need a good trigger signal, which up to now I have generated with an
oscilloscope that has a trigger output. But this signal is not very good,
probably it's 'cause the scope is not the best one.

So my question is, how do I generate a good trigger signal from a sine
signal with an amplitude about 10V-50V? It seems a pretty simple task, but
up to now I haven't found any device that does this job. Neither in
google, nor at the major test equipment suppliers. I am also not very good
at soldering, though if the circuit is very simple and the risk to screw
it is not very high I might try it.

---
If you can't find anything and you're not good at building stuff,
I'll be happy to build something for you that does just what you
want for a reasonable price. Email me if you're interested.

--
John Fields
Professional Circuit Designer

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Alexander Frey wrote:
[snip]
So my question is, how do I generate a good trigger signal from a sine
signal with an amplitude about 10V-50V? It seems a pretty simple task,
but up to now I haven't found any device that does this job. Neither
in google, nor at the major test equipment suppliers. I am also not
very good at soldering, though if the circuit is very simple and the
risk to screw it is not very high I might try it.
[snip]


Half-wave rectifier + Schmitt trigger?

Chris
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.2.1 (MingW32)

iD8DBQFDE6zf6ZGQ8LKA8nwRAvYoAJ4mgqoi1hgQ3g+ZsModhC kYsGH47wCfaPMO
rg2Dfo0fNKXeV4JOKpiAwUE=
=CpOW
-----END PGP SIGNATURE-----

In article , Alexander Frey wrote:
Hi all.

I want to synchronize a laser pulse with an AC current (only about 1kHz)

So my question is, how do I generate a good trigger signal from a sine
signal with an amplitude about 10V-50V? It seems a pretty simple task, but
up to now I haven't found any device that does this job.

first off which part othe wave do you want to trigger on.
the crest (maximum voltage), zero crossing (when the voltage changes from
positive to negative), or some other point.

Neither in
google, nor at the major test equipment suppliers. I am also not very good
at soldering, though if the circuit is very simple and the risk to screw
it is not very high I might try it.

good quality solder, and a clean soldering iron will always help
stay away from plumbers solder

something can probably be done with an op-amp chip and a few other parts.

--

Bye.
Jasen

On Tue, 30 Aug 2005 22:13:23 +1200, Jasen Betts
wrote:

In article , Alexander Frey wrote:
Hi all.

I want to synchronize a laser pulse with an AC current (only about 1kHz)

So my question is, how do I generate a good trigger signal from a sine
signal with an amplitude about 10V-50V? It seems a pretty simple task, but
up to now I haven't found any device that does this job.

first off which part othe wave do you want to trigger on.
the crest (maximum voltage), zero crossing (when the voltage changes from
positive to negative), or some other point.

Neither in
google, nor at the major test equipment suppliers. I am also not very good
at soldering, though if the circuit is very simple and the risk to screw
it is not very high I might try it.

good quality solder, and a clean soldering iron will always help
stay away from plumbers solder

something can probably be done with an op-amp chip and a few other parts.

---
Got a clue as to how to do it?

--
John Fields
Professional Circuit Designer

Am Tue, 30 Aug 2005 02:48:33 +0200 schrieb Chris Head
:
[...]

Half-wave rectifier + Schmitt trigger?

Ok. A google search on schmitt triggers finally turns up the thing I've
been looking for. And the circuit actually seems pretty simple so that
even I probably could do it.

Thanks,
Alex

----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups
----= East and West-Coast Server Farms - Total Privacy via Encryption =----

Am Tue, 30 Aug 2005 12:13:23 +0200 schrieb Jasen Betts
:

In article , Alexander Frey
wrote:
Hi all.

I want to synchronize a laser pulse with an AC current (only about 1kHz)

So my question is, how do I generate a good trigger signal from a sine
signal with an amplitude about 10V-50V? It seems a pretty simple task,
but
up to now I haven't found any device that does this job.

first off which part othe wave do you want to trigger on.
the crest (maximum voltage), zero crossing (when the voltage changes from
positive to negative), or some other point.

Actually, I need the trigger signal to drive a digital delay generator
that himself makes a trigger pulse with a variable phase to the AC. With
this pulse the laser is fired, so that I can adjust the time the laser
fires on a sample with respect to a current flowing through the sample.
So it really doesn't matter on which point of the sine wave I trigger,
because i can reach every phase position with the delay generator. But the
best point o trigger on would probably be one on the rising/falling slope,
rather than the tip of the wave I guess. As I said in another post I'll
try the Schmitt trigger curcuit.

good quality solder, and a clean soldering iron will always help
stay away from plumbers solder

something can probably be done with an op-amp chip and a few other parts.

Oops, I just ordered two hundred pounds of plumbers solder on ebay because
it was less expensive than the other type. Was that a bad idea?

Thanks folks,
Alex

----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups
----= East and West-Coast Server Farms - Total Privacy via Encryption =----

"Alexander Frey" schreef in bericht
news
Am Tue, 30 Aug 2005 12:13:23 +0200 schrieb Jasen Betts
:

snip
good quality solder, and a clean soldering iron will always help
stay away from plumbers solder

something can probably be done with an op-amp chip and a few other parts.

Oops, I just ordered two hundred pounds of plumbers solder on ebay because
it was less expensive than the other type. Was that a bad idea?

Not terrible, you can always another career if you like, for the first few
years you have enough Pb.
Something just hit me, it's something called RoHS
Especially for a new design it might be a good idea to keep that in mind. It
hit me to hard I can't get it out of my mind.
But don't be sad, it just needs some more solder practice

Thanks folks,
Alex


Good Luck,

Alexander

In article , John Fields wrote:

On Tue, 30 Aug 2005 22:13:23 +1200, Jasen Betts
wrote:


first off which part othe wave do you want to trigger on.
the crest (maximum voltage), zero crossing (when the voltage changes from
positive to negative), or some other point

Neither in
google, nor at the major test equipment suppliers. I am also not very good
at soldering, though if the circuit is very simple and the risk to screw
it is not very high I might try it.

good quality solder, and a clean soldering iron will always help
stay away from plumbers solder

something can probably be done with an op-amp chip and a few other parts.

Got a clue as to how to do it?

A few, but I know you're the expert here... I only do electronics for fun.


something like this could be a start

+V --+----
|
| +-----[10K]--+
| | |\ |
----[1K]-)--+-|+\ |
in | | -------+---||--
---0V \ +-|-/ out
/-+ |/ 0V ----
\
|
-V----+---

Bye.
Jasen

In article , Alexander Frey wrote:
Am Tue, 30 Aug 2005 12:13:23 +0200 schrieb Jasen Betts
:

first off which part othe wave do you want to trigger on.
the crest (maximum voltage), zero crossing (when the voltage changes from
positive to negative), or some other point.

Actually, I need the trigger signal to drive a digital delay generator
that himself makes a trigger pulse with a variable phase to the AC. With
this pulse the laser is fired, so that I can adjust the time the laser
fires on a sample with respect to a current flowing through the sample.
So it really doesn't matter on which point of the sine wave I trigger,
because i can reach every phase position with the delay generator. But the
best point o trigger on would probably be one on the rising/falling slope,
rather than the tip of the wave I guess. As I said in another post I'll
try the Schmitt trigger curcuit.


if that 10-50V ac has an unstable amplitude
some sort of schmitt circuit with a variable offset to allow you to get it
to trigger on the zero crossing (in one direction) may probably help you to
match the phase better...

--

Bye.
Jasen

On Fri, 2 Sep 2005 22:31:34 +1200, Jasen Betts
wrote:

In article , John Fields wrote:

On Tue, 30 Aug 2005 22:13:23 +1200, Jasen Betts
wrote:


first off which part othe wave do you want to trigger on.
the crest (maximum voltage), zero crossing (when the voltage changes from
positive to negative), or some other point

Neither in
google, nor at the major test equipment suppliers. I am also not very good
at soldering, though if the circuit is very simple and the risk to screw
it is not very high I might try it.

good quality solder, and a clean soldering iron will always help
stay away from plumbers solder

something can probably be done with an op-amp chip and a few other parts.

Got a clue as to how to do it?

A few, but I know you're the expert here... I only do electronics for fun.


something like this could be a start

+V --+----
|
| +-----[10K]--+
| | |\ |
----[1K]-)--+-|+\ |
in | | -------+---||--
---0V \ +-|-/ out
/-+ |/ 0V ----
\
|
-V----+---

---
A misguided start.

1. You haven't provided any attenuation of the input signal.
It can go to +/- 50V, remember?

2. If the amplitude of the input voltage goes beyond the supply
rails:

a. The pot will only be effective in selecting input
voltages between the rails.

b. The comparator could fry.

3. The input impedance is way too low.

4. You've got way too much hysteresis in there.

5. Take that "expert" crack and stick it up your ass, you arrogant
little prick.

--
John Fields
Professional Circuit Designer

On Fri, 2 Sep 2005 22:38:45 +1200, Jasen Betts
wrote:

In article , Alexander Frey wrote:
Am Tue, 30 Aug 2005 12:13:23 +0200 schrieb Jasen Betts
:

first off which part othe wave do you want to trigger on.
the crest (maximum voltage), zero crossing (when the voltage changes from
positive to negative), or some other point.

Actually, I need the trigger signal to drive a digital delay generator
that himself makes a trigger pulse with a variable phase to the AC. With
this pulse the laser is fired, so that I can adjust the time the laser
fires on a sample with respect to a current flowing through the sample.
So it really doesn't matter on which point of the sine wave I trigger,
because i can reach every phase position with the delay generator. But the
best point o trigger on would probably be one on the rising/falling slope,
rather than the tip of the wave I guess. As I said in another post I'll
try the Schmitt trigger curcuit.


if that 10-50V ac has an unstable amplitude
some sort of schmitt circuit with a variable offset to allow you to get it
to trigger on the zero crossing (in one direction) may probably help you to
match the phase better...

---
Why not just say, "Use a PIC."?

--
John Fields
Professional Circuit Designer

In article , John Fields wrote:

if that 10-50V ac has an unstable amplitude
some sort of schmitt circuit with a variable offset to allow you to get it
to trigger on the zero crossing (in one direction) may probably help you to
match the phase better...

---
Why not just say, "Use a PIC."?

I wouldn't say that, an AVR maybe, but I have no erperience with PICs

I was thinking more along the lines of a potentiometer between +V and -V
wity the output to one of the op-amp inputs so that one of the switching
points of the schmitt could be positioned at 0V...

Bye.
Jasen

In article , John Fields wrote:

something like this could be a start

+V --+----
|
| +-----[10K]--+
| | |\ |
----[1K]-)--+-|+\ |
in | | -------+---||--
---0V \ +-|-/ out
/-+ |/ 0V ----
\
|
-V----+---

---
A misguided start.

1. You haven't provided any attenuation of the input signal.
It can go to +/- 50V, remember?

Actually I had forgotten while writing that.

3. The input impedance is way too low.

yeah.

4. You've got way too much hysteresis in there.

1:10 is too much? - I guess it depends on the amplitude of the input signal.

5. Take that "expert" crack and stick it up your ass, you arrogant
little prick.

I think you're selling yourslf short. (It wasn't intended as a crack)

--

Bye.
Jasen

On Sat, 3 Sep 2005 23:59:48 +1200, Jasen Betts
wrote:

In article , John Fields wrote:

5. Take that "expert" crack and stick it up your ass, you arrogant
little prick.

I think you're selling yourslf short. (It wasn't intended as a crack)

---
I never sell myself short, and I'm sensitive to slurs, which your
statement came across as.

--
John Fields
Professional Circuit Designer