Function Generator - wave form base level?

T

Terry Pinnell

Guest
Overall I'm very happy with my ancient (but initially expensive,
top-end) Philips PM 5134 Function Generator. But one thing I can't do
with it strikes me as a serious weakness. I can't output a single
POSITIVE GOING rectangular pulse (or a burst of them). I've
illustrated it here:
http://www.terrypin.dial.pipex.com/Images/WaveformBase.gif

Is this just a design quirk of my instrument, or do most function
generators output do this? I rarely want -ve going pulses, but
frequently would like to produce a single +ve going one (with variable
amplitude and period).

--
Terry Pinnell
Hobbyist, West Sussex, UK
 
Hi Terry,

That may be a bit much to ask from a function generator. Pulse generators
are the instruments for this and the PM5785, for example, can do pulse
trains nicely. It has a clickable count selector which you can set from
one to 9999 pulses.

Regards, Joerg
http://www.analogconsultants.com
 
Joerg <notthisjoergsch@removethispacbell.net> wrote:

Hi Terry,

That may be a bit much to ask from a function generator. Pulse generators
are the instruments for this and the PM5785, for example, can do pulse
trains nicely. It has a clickable count selector which you can set from
one to 9999 pulses.

Regards, Joerg
http://www.analogconsultants.com
Click to expand...
Thanks Joerg. It seems odd that I have to fall back on my home brewed
pulse generator instead of being able to use an instrument that cost
several thousand pounds/dollars in its day.

Do other function generators produce -ve going pulses in Trigger or
Burst mode?

--
Terry Pinnell
Hobbyist, West Sussex, UK
 
Hi Terry,

I can only speak for the PM5785 which is a pulse generator. It allows negative
pulses and you can even add an offset.

The Wavetek Model 23 also allows both directions as far as I know but no
bursts. That is a true function generator which does not allow bursts (but can
be triggered). I don't know of any function generator that can do bursts.

Regards, Joerg

http://www.analogconsultants.com
 
Terry Pinnell wrote...
Overall I'm very happy with my ancient (but initially expensive,
top-end) Philips PM 5134 Function Generator. But one thing I can't do
with it strikes me as a serious weakness. I can't output a single
POSITIVE GOING rectangular pulse (or a burst of them). I've
illustrated it here:
http://www.terrypin.dial.pipex.com/Images/WaveformBase.gif
Click to expand...
You should certainly be able to get a single pulse, something must
be wrong with your generator. Other Philips generators, as Joerg
mentioned, do create trains of pulses. I have two on my bench,
and they are very useful. I just wish they were smaller!

Thanks,
- Win

(email: use hill_at_rowland-dot-org for now)
 
Terry Pinnell <terrypin@dial.pipex.com> wrote in
news:sr0q90p9hqld2neq630sf1sfbr4510kj7h@4ax.com:

Overall I'm very happy with my ancient (but initially expensive,
top-end) Philips PM 5134 Function Generator. But one thing I can't do
with it strikes me as a serious weakness. I can't output a single
POSITIVE GOING rectangular pulse (or a burst of them). I've
illustrated it here:
http://www.terrypin.dial.pipex.com/Images/WaveformBase.gif

Is this just a design quirk of my instrument, or do most function
generators output do this? I rarely want -ve going pulses, but
frequently would like to produce a single +ve going one (with variable
amplitude and period).
Click to expand...
Doesn't your FG have a variable DC offset that can be applied to the output
signal?

--
Jim Yanik
jyanik-at-kua.net
 
Jim Yanik <jyanik@abuse.gov> wrote:

Terry Pinnell <terrypin@dial.pipex.com> wrote in
news:sr0q90p9hqld2neq630sf1sfbr4510kj7h@4ax.com:

Overall I'm very happy with my ancient (but initially expensive,
top-end) Philips PM 5134 Function Generator. But one thing I can't do
with it strikes me as a serious weakness. I can't output a single
POSITIVE GOING rectangular pulse (or a burst of them). I've
illustrated it here:
http://www.terrypin.dial.pipex.com/Images/WaveformBase.gif

Is this just a design quirk of my instrument, or do most function
generators output do this? I rarely want -ve going pulses, but
frequently would like to produce a single +ve going one (with variable
amplitude and period).


Doesn't your FG have a variable DC offset that can be applied to the output
signal?
Click to expand...
Yes, it does, as I said on the illustration. But, as that shows, it
produces ONLY a -ve going pulse, like this:

-------------+ +---------------
| |
| |
| |
| |
| |
+-------+

instead of the +ve going pulse I want, like this:

+--------+
| |
| |
| |
| |
--------------+ +---------------

created by Andy´s ASCII-Circuit v1.23.080803 Beta www.tech-chat.de

--
Terry Pinnell
Hobbyist, West Sussex, UK
 
Winfield Hill <Winfield_member@newsguy.com> wrote:

Terry Pinnell wrote...

Overall I'm very happy with my ancient (but initially expensive,
top-end) Philips PM 5134 Function Generator. But one thing I can't do
with it strikes me as a serious weakness. I can't output a single
POSITIVE GOING rectangular pulse (or a burst of them). I've
illustrated it here:
http://www.terrypin.dial.pipex.com/Images/WaveformBase.gif

You should certainly be able to get a single pulse, something must
be wrong with your generator. Other Philips generators, as Joerg
mentioned, do create trains of pulses. I have two on my bench,
and they are very useful. I just wish they were smaller!
Click to expand...
I take it your reference to 'pulse' and 'pulses' above are all meant
to be prefaced by 'positive'? As I said, I *can* get a single negative
pulse, or bursts of them.

As Joerg pointed out, his instrument is a Pulse Generator.

The PM5134 otherwise seems pretty versatile, as you see from this
http://www.terrypin.dial.pipex.com/Images/FrontPanel2.jpg
hence my question about other FGs.


--
Terry Pinnell
Hobbyist, West Sussex, UK
 
"Terry Pinnell" <terrypin@dial.pipex.com> a écrit dans le message news:
55pr90d3p2q1alcjoeicm1vo4sd9g2du9s@4ax.com...
Jim Yanik <jyanik@abuse.gov> wrote:

Terry,
Click to expand...
from the grass I see on the blue waveforms I believe these are real ones.

So your PM... can generate single pulses.
I also understand that it has setting for positive, negative and dual
polarity rectangular pulses and it only delivers negative pulses, whatever
the setting.
So there must be something wrong with your generator, probably not difficult
to fix.

Thanks,
Fred.
 
Terry Pinnell wrote...
The PM5134 otherwise seems pretty versatile, as you see from this
http://www.terrypin.dial.pipex.com/Images/FrontPanel2.jpg
hence my question about other FGs.
Click to expand...
Your instrument should be symmetrical with respect to polarity.
You may need to play with the dc-offset and duty-cycle controls.

Thanks,
- Win

(email: use hill_at_rowland-dot-org for now)
 
Terry Pinnell wrote...
The PM5134 otherwise seems pretty versatile, as you see from this
http://www.terrypin.dial.pipex.com/Images/FrontPanel2.jpg
hence my question about other FGs.
Click to expand...
Your instrument should be symmetrical with respect to polarity.
You may need to play with the dc-offset and duty-cycle controls.

Oh, and the start-phase control as well.

Thanks,
- Win

(email: use hill_at_rowland-dot-org for now)
 
On Sun, 09 May 2004 09:31:23 +0100, Terry Pinnell
<terrypin@dial.pipex.com> wrote:


I take it your reference to 'pulse' and 'pulses' above are all meant
to be prefaced by 'positive'? As I said, I *can* get a single negative
pulse, or bursts of them.

As Joerg pointed out, his instrument is a Pulse Generator.

The PM5134 otherwise seems pretty versatile, as you see from this
http://www.terrypin.dial.pipex.com/Images/FrontPanel2.jpg
hence my question about other FGs.
Click to expand...
The DC Offset control should move the whole waveform in a positive or
negative direction. The Duty Cycle control will adjust the width of
the pulses. If the duty cycle is set to, say, 90%, the output will be
high for 90% of the time, and low for 10, so it looks like a
negative-going pulse. If you set the Duty Cycle to 10%, you should
have the positive-going pulse that you want (and 50% Duty Cycle should
give you a square wave).



--
Peter Bennett, VE7CEI
peterbb4 (at) interchange.ubc.ca
new newsgroup users info : http://vancouver-webpages.com/nnq
GPS and NMEA info: http://vancouver-webpages.com/peter
Vancouver Power Squadron: http://vancouver.powersquadron.ca
 
Peter Bennett <peterbb@somewhere.invalid> wrote:

On Sun, 09 May 2004 09:31:23 +0100, Terry Pinnell
terrypin@dial.pipex.com> wrote:


I take it your reference to 'pulse' and 'pulses' above are all meant
to be prefaced by 'positive'? As I said, I *can* get a single negative
pulse, or bursts of them.

As Joerg pointed out, his instrument is a Pulse Generator.

The PM5134 otherwise seems pretty versatile, as you see from this
http://www.terrypin.dial.pipex.com/Images/FrontPanel2.jpg
hence my question about other FGs.

The DC Offset control should move the whole waveform in a positive or
negative direction. The Duty Cycle control will adjust the width of
the pulses. If the duty cycle is set to, say, 90%, the output will be
high for 90% of the time, and low for 10, so it looks like a
negative-going pulse. If you set the Duty Cycle to 10%, you should
have the positive-going pulse that you want (and 50% Duty Cycle should
give you a square wave).
Click to expand...
No, neither control can be used to make the pulses NEGATIVE-GOING, as
I explained. See further illustration at
http://www.terrypin.dial.pipex.com/Images/WaveformBase2.gif
Sweeping Duty Cycle throughout its range simply affects the duty cycle
of the pulses. The intervening signal, whether between burst or single
pulses, remains HIGH.

Increasing or reducing DC Offset simply does that! The base-line (if
that's the right term) again remains HIGH for all 3 'rectangular'
settings of Wave Form, as I originally described.

Like Fred, I'm regrettably coming to the conclusion that something may
be broken.

But before I fianlly conclude that, I'd still like to hear from users
of other FGs, especially about the waveforms produced when they are
set in equivalent modes to those three rectangular types. As I said, I
had originally vaguely thought perhaps that this 'high base-line' was
a general characteristic of professional FGs - at least older types
like this one - when set to rectangular modes.

--
Terry Pinnell
Hobbyist, West Sussex, UK
 
Terry,

I have just bought a PM 5134 on EBay for $160 including shipping and
await it arrival. I would be happy to experiment with its pulse
settings and let you know what I find. Unfortunately, the unit I
bought does not have a manual. I have tried searching the web for a
manual with absolutely no success. Do you know of a source for the
manual? Also, do you know when Philips stopped manufacturing the 5134?

Sincerely

Thomas Philips
 
"Thomas Philips" <tkpmep@hotmail.com> a écrit dans le message news:
b4a8ffb6.0405091140.2592111a@posting.google.com...
Terry,

I have just bought a PM 5134 on EBay for $160 including shipping and
await it arrival. I would be happy to experiment with its pulse
settings and let you know what I find. Unfortunately, the unit I
bought does not have a manual. I have tried searching the web for a
manual with absolutely no success. Do you know of a source for the
manual? Also, do you know when Philips stopped manufacturing the 5134?
Click to expand...
Try this :
http://www.dse.nl/~schemath/english.html

I've once contacted them. They were slooow but I finally got a contact
(several weeks later).

They seem to have almost everything possible about Philips.

Thanks,
Fred.
 
"Terry Pinnell" <terrypin@dial.pipex.com> wrote in message
news:jhps90hm5kub4kn4al3s93m6ijobh83761@4ax.com...
Peter Bennett <peterbb@somewhere.invalid> wrote:

No, neither control can be used to make the pulses NEGATIVE-GOING, as
I explained. See further illustration at
http://www.terrypin.dial.pipex.com/Images/WaveformBase2.gif
Sweeping Duty Cycle throughout its range simply affects the duty cycle
of the pulses. The intervening signal, whether between burst or single
pulses, remains HIGH.
Click to expand...
If you can adjust the DC offset, and if we're talking about a continuous
pulse train, what's the difference between a negative-going pulse with
baseline, say, +5V, amplitude -5V, duty cycle 90%, and a positive-going
pulse with baseline 0, amplitude +5, and duty cycle 10%?

Thanks,
Rich
 
Rich Grise wrote...
If you can adjust the DC offset, and if we're talking about a continuous
pulse train, what's the difference between a negative-going pulse with
baseline, say, +5V, amplitude -5V, duty cycle 90%, and a positive-going
pulse with baseline 0, amplitude +5, and duty cycle 10%?
Click to expand...
Plus the start-phase control may be useful.

Thanks,
- Win

(email: use hill_at_rowland-dot-org for now)
 
tkpmep@hotmail.com (Thomas Philips) wrote:

Terry,

I have just bought a PM 5134 on EBay for $160 including shipping and
await it arrival. I would be happy to experiment with its pulse
settings and let you know what I find. Unfortunately, the unit I
bought does not have a manual. I have tried searching the web for a
manual with absolutely no success. Do you know of a source for the
manual? Also, do you know when Philips stopped manufacturing the 5134?
Click to expand...

Thomas: I got mine via ebay too, in the UK. And the first thing I did
was dig deep for a manual! Very expensive, at 40.53UKP (about 73USD),
but I couldn't survive without one <g>.

Philips were taken over by Fluke, and so I tracked down my local Fluke
agent. I assume you're in USA, so none of the phone numbers I've
looked up will help you, but I expect you'll have no trouble finding a
Fluke distributor. Maybe you won't be as impatient as I was, and can
find a used copy? Meanwhile, if you have a specific query, I'll
happily scan the appropriate section and email you. (Much of it
consists of large, fold-out diagrams though, so is hard to handle for
scanning.)

I'm hoping one of the first things you can try are the settings I've
described in this thread!


--
Terry Pinnell
Hobbyist, West Sussex, UK
 
"Rich Grise" <null@example.net> wrote:

"Terry Pinnell" <terrypin@dial.pipex.com> wrote in message
news:jhps90hm5kub4kn4al3s93m6ijobh83761@4ax.com...
Peter Bennett <peterbb@somewhere.invalid> wrote:

No, neither control can be used to make the pulses NEGATIVE-GOING, as
I explained. See further illustration at
http://www.terrypin.dial.pipex.com/Images/WaveformBase2.gif
Sweeping Duty Cycle throughout its range simply affects the duty cycle
of the pulses. The intervening signal, whether between burst or single
pulses, remains HIGH.


If you can adjust the DC offset, and if we're talking about a continuous
pulse train,
Click to expand...
....which we're not. We're talking about single pulses or bursts. Did
you read the thread and/or study the illustrations?

what's the difference between a negative-going pulse with
baseline, say, +5V, amplitude -5V, duty cycle 90%, and a positive-going
pulse with baseline 0, amplitude +5, and duty cycle 10%?
Click to expand...
Nothing.

--
Terry Pinnell
Hobbyist, West Sussex, UK
 
Winfield Hill <Winfield_member@newsguy.com> wrote:

Rich Grise wrote...

If you can adjust the DC offset, and if we're talking about a continuous
pulse train, what's the difference between a negative-going pulse with
baseline, say, +5V, amplitude -5V, duty cycle 90%, and a positive-going
pulse with baseline 0, amplitude +5, and duty cycle 10%?

Plus the start-phase control may be useful.
Click to expand...
That seems to have no effect for these three rectangular settings of
the Wave Form control.

What FG do you use Win? What does its single pulse output look like
when set to say a +ve square or rectangular wave? Which of the two
baselines I illustrated?


--
Terry Pinnell
Hobbyist, West Sussex, UK
 
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