pulse integrator
pulse integrator
(OP)
I need to develop a circuit that will integrate a pulsed voltage signal and provide an analog output to be fed to a PLC module. The pulses are from one to five milliseconds long, with a pulse rate maximum of around 30 Hz. I'd like to be able to reset the integrator between pulses. With current circuitry, the input voltage is around 1 V, coming from a LEM.
I've got a schematic of an integrator using a LM101A, but I'm not an EE and am more than a little unsure about how exactly to put this together. We don't have enough work for an EE full time, and have not been able to find anyone locally (we're in Gardena, CA) to help us on this.
Any help on this would be greatly appreciated.
I've got a schematic of an integrator using a LM101A, but I'm not an EE and am more than a little unsure about how exactly to put this together. We don't have enough work for an EE full time, and have not been able to find anyone locally (we're in Gardena, CA) to help us on this.
Any help on this would be greatly appreciated.
Jim Treglio
Molecular Metallurgy, Inc.





RE: pulse integrator
If you reset it, why to integrate?
Read my FAQ, please !!!!
What is the purpose and requirements?
Plesae read FAQ240-1032
My WEB: <http://geocities.com/nbucska/>
RE: pulse integrator
Plesae read FAQ240-1032
My WEB: <http://geocities.com/nbucska/>
RE: pulse integrator
RE: pulse integrator
LEM = Liaison Electro Mecanique. They produce Hall devices to measure DC current.
As cbarn says. Use a simple micro (there are those in 8 pin housings nowadays) to measure pulse width and a PWM output to produce a DC voltage.
You will probably (for sure) need a comparator to sharpen up your pulse and a smooting circuit plus amplifier to get the (probably) 0 - 10 V needed by the PLC.
I think that you can contact any competent consultant via the net and have this done in a couple of days.
Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: pulse integrator
Jim Treglio
Molecular Metallurgy, Inc.
RE: pulse integrator
The best way seems to be using a suitably fast integrator and transfer the analoge value to a second hold capacitor at the end of the pulse. Use a buffer between the hold capacitor and the output.
A good quad opamp, an analogue switch (possibly a 4066 style) and some logic is all you need. Plus, of course, a few capacitors and resistors.
Depending on how you define "the end of the pulse", you will get a small and constant offset error, which can be adjusted for. You can then reset the integrator and wait for the next pulse.
Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: pulse integrator
What kind of accuracy do you need per pulse and per
10 min. cycles? What is the speed of the PLC?
If I understand, You use a HALL device to measure the
current of the arc. Why not optocoupler? the HALL is less
linear.
Plesae read FAQ240-1032
My WEB: <http://geocities.com/nbucska/>
RE: pulse integrator
RE: pulse integrator
I usually reach for a micro to do it all or to control the analog stuff so changes can be implemented in software in lue of hardware. Micros are just so much more nimble in tuning and for the inevitable modifications that come along.
Your LEMs are horrifically expensive any chance of using shunts?
Is this a 1-off or something you're going to make many of?
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: pulse integrator
Please specify required accuracy etc.
Plesae read FAQ240-1032
My WEB: <http://geocities.com/nbucska/>
RE: pulse integrator
Jim Treglio
Molecular Metallurgy, Inc.
RE: pulse integrator
You might want to consider using some metallic foil as a shield connected to frame earth inside the bore of the LEM, especially if your conductor voltage changes rapidly relaltive to ground. Many LEMs are sensitive to breakthrough when high dv/dt on the conductor appears on the LEM output as a false current signal. If you can sense current on a conductor at or near earth potential the effect does not occur. The shield must not form a shorted turn: I used a Chomerics self adhesive foil to line the bore and cover the end faces only and soldered a drain wire to the foil.
----------------------------------
Sometimes I only open my mouth to swap feet...
RE: pulse integrator
That is real good advice. Arcing inevitably produces high dv/dt. And it couples into anything nearby.
Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: pulse integrator
bagotronix or jkmicro (www -.com) from $69.-
Use an 8 bit ADC and just integrate it in software.
Plesae read FAQ240-1032
My WEB: <http://geocities.com/nbucska/>
RE: pulse integrator