Need a Voltage Pulse Measurement

These guys probably got something you could use.....

http://www.keithley.com/promo/wb/201

Assuming this isn't for permanent monitoring and is a kind of once-off test then google "DVM with peak hold". There are lots.

Many DVM with peak hold feature need more than 5 mS to update the value. The Fluke 179 I am using right now needs 900 mS of a value to trigger the function. The user manual is an engineer's best friend.

welderman:

Unless you tell the accuracy you need, how to determine it? Is it 0.1% or 0.01% or 0.001% in accuracy and do you need only for the peak voltage or want to know how this peak looks like in the form of waveform?

1.0% or better accuracy would be good. I have memory scope images of individual waveforms but it is difficult to make accurate measurements from these waveforms.

welderman:

DSO usually use 8-bit ADC so 1% accuracy must be easily feasible. Its precision is better than 0.5%. Try some cheap 12-bit USB data recorder. Perhaps you can try National Instruments

NI USB-600812-Bit, 10 kS/s Low-Cost Multifunction DAQ

Does your DSO have cursors, or, can you dump the waveform to a CSV file.

If your existing oscilloscope does not have the required capabilities pico scope's 4000 series have 12 bit resolution for under $1000.

http://www.picotech.com/picoscope4000.html

You should also consider looking into various vendors of voltage loggers, several of which have up to 36000 samples/sec or more. They can also give you just the peak value, of a train of a number of pulses, single trigger, etc. Or you can get the rms value if you want that. You will have very precise and accurate recordings of the values.

Scientific Messtechnique (also deals in RIGOL make) in Germany makes Digital Scopes with measurement features. You can use it to compute many voltage and time base features I have a DSO at home which I use regularly- if you are using analog scope it is difficult. Peak, Average, rms, peal to peak and so many features.

BUT TROUBLE is - let me tell you- sometimes there may be a micro or nano sec spike, but are looking for msec wide peak pulse- then DSO cannot segregate. Then you will have to use cursor and manually measure.

You could use the following circuit in order to measure the pulse's amplitude:

The buffer stage can be used for isolation of the output (so that the voltmeter will not discharge the capacitor). Of course you have to compensate the 0,7V (or 0,3V for schottky diodes) in order to get the actual value of the pulse. So the better way is to use an "ideal diode" circuit (an active circuit consisting of a op amp and a diode) instead of a simple diode. With such a circuit you can measure the pulse's amplitude using a voltmeter at the output. The capacitor should have a rather low value so that it can be fully charged during the presence of the input pulse.

The only problem is that the capacitor will be discharged vary slowly -right after the input pulse is gone- through the diode, the buffer's input circuitry and it's dielectric leakage. So the very first indication that you'll see on the voltmeter's screen will be the most correct. (Of course, you could improve the circuit by -e.g.- using a kind of fast relay in series with the diode which will be opened right after the presence of the input pulse so that you will avoid the discharge of the capacitor through the diode.)

I believe Agilent Technologies has digital scopes with sufficient accuracy. If you design your own circuit, you will have to calibrate it with some kind of standard. Use that standard to calibrate your scope.

I use this all the time and it appears to be accurate. Do a search on "disco" usb. Around $129.Has many functions and the record function is used the most. Here is the output of a NEMA 17 stepper motor with the shaft being turned by hand.

I'm not completely sure what you're exactly trying to achieve. But from my interpretation of the information available, I managed to find this.

http://www.london-electronics.com/fast-peak-hold-digital-meter.php

Hope it helps.

Thanks. That,s exactly what I'm looking for. I have sent to the company for detailed information.

I'm glad it was what you were looking for.

All the Best.