I have a need to measure current and fuse trip time and need to be portable. I suppose I can somehow rig it up to test at my workbench but would like the freedom to be portable.

Need to measure about 3-20 A @ 15V tops I'm guessing about few miliseconds to maybe 20mS tops - will put inline shunt. So a decent current measurement is needed

Two I would like to see the waveform as the fuse trips and be able to document the time and current...

If there are decent handheld oscilloscope or device to record this data... would be great if anyone can point me in the right direction. Will be doing some analysis by capturing this data over time... maybe a data logger???

What's the best way... is it better to use a current probe? Can this be achieved without spending tons?

Thanks,
Charlie

 

The first thing I would do is question the manufacturer for data. You might need to open a lot of fuses without data. I am not a fuse man, is there such data?

I would want to know if the duration of the event is consistent with voltage and temp. Then the duration of the event.

Then decide the strategy for measuring/observing it. How many slices of the event do you want to measure?

This tells you your measuring time scale. That will tell you the cost of scope. No special probes are needed, you can measure the current's voltage.(shunt voltage)

 

The fuse was just a visual tool... actual measurement will be for homemade model rocket igniters. The plan is to test different combinations of voltage, current, wire size, and pyro-materials to figure out the most efficient combinations. It's also fun to document it and have measurable details.

In the summer months, I am active with the local Tripoli Rocket Association http://www.tripoliwisconsin.org/. I'm always trying to bring some more inner nerdiness to our hobby. It's a lot of fun.

So a portable device that can be taken on site to record data would be amazing. I suppose a lap top could be used but all in one would simplify the gear I have to take and battery to maintain.

 

Absolute cheapest "throwaway" handheld scopes.

No memory
/www.aliexpress.com/item/New-2-4-TFT-Pocket-size-Digital-Oscilloscope-Kit-DIY-Parts-Handheld-Acrylic-DIY-Case-Cover/32958645902.html?spm=2114.search0104.3.114.390a1550goflKl&ws_ab_test=searchweb0_0,searchweb201602_1_10065_10130_10068_10890_10547_319_10546_317_10548_10545_10696_453_10084_454_10083_10618_10307_537_536_10059_10884_10887_321_322_10103,searchweb201603_52,ppcSwitch_0&algo_expid=af27bfa5-c4c2-4eea-92c6-bdb19ff812b5-21&algo_pvid=af27bfa5-c4c2-4eea-92c6-bdb19ff812b5&transAbTest=ae803_5

Some memory
https://www.aliexpress.com/item/NEW...8e-44f6-94a2-bcaf7d0c60c8&transAbTest=ae803_5

 

Can this be achieved without spending tons?

Define "tons". If you are only looking to measure this one item then almost any low cost scope will probably work. A shunt would also work. If you want to measure other circuits then you will need to select a better scope. You may also want to use a current probe. Here is a reasonably priced probe that will meet your needs:
https://www.amazon.com/Hantek®-Curr...current+probe&qid=1559783355&s=gateway&sr=8-3

I have a Hantek DSO8060 portable scope. It is a decent scope but not top of the line. However it is good for the price, about $500 +- at Amazon.

 

Forgot to mention, the current probe is good to 20KHz and is about $60. For about twice that you can get 300KHz.

 

Define "tons". If you are only looking to measure this one item then almost any low cost scope will probably work. A shunt would also work. If you want to measure other circuits then you will need to select a better scope. You may also want to use a current probe. Here is a reasonably priced probe that will meet your needs:
https://www.amazon.com/Hantek®-Current-Clamp-kHz-20mA/dp/B06W2KFZLW/ref=sr_1_3?gclid=EAIaIQobChMIuoi52tXT4gIVk7bACh2NzwXmEAAYASAAEgKsxfD_BwE&hvadid=176297620937&hvdev=c&hvlocphy=9025737&hvnetw=g&hvpos=1t1&hvqmt=e&hvrand=9823612856129193055&hvtargid=kwd-151195675&hydadcr=13149_9591369&keywords=oscilloscope+current+probe&qid=1559783355&s=gateway&sr=8-3

I have a Hantek DSO8060 portable scope. It is a decent scope but not top of the line. However it is good for the price, about $500 +- at Amazon.

That’s a nice looking scope I have a bench scope so just need a portable unit can’t think of any other uses for it for now. A current probe would be nice that way there is no load on the circuit. I will have to research portable scopes. I’m sure I’ll find other uses for them in the future.

I would like to test different voltages (and current) and figure out the ignition time for various resistance igniters. I’m sure the better designs will rise to the top.

 

The DSO150 can be had really cheap like maybe $25.00 with a x1/x10 probe, but no power supply. You can strap a 9V battery holder to DC barrel jack on the back with rubber band.

For your measurements, you might need cursurs. It looks like you need the pre-trigger event. You might want to build a box to set that level easily, but for that you would need an external trigger.

POLOLU as come hall effect current sensors. You might find an adjustable reference on ebay or Amazon, I know there are 0-10V and 4-20 mA things, but they might require 24 V or so. Anyway, if you need a 0-5V signal. convert the 0-20mA to a voltage.

e.g. https://www.amazon.com/Generator-DROK-Adjustable-Transmitter-Simulation/dp/B071NLGP6L

You might find something similar that allows process units.

 

Since the ignition event is controlled it would not be difficult to trigger the scope right before the ignition event. Do any of them have a buffer to capture moments right before a trigger?

DSO150 would be bare bones and at $25 very affordable...

Ideally something that kept this in memory or dumped to laptop would make analysis easier.

This one is just under $100 by kkmoon 5012H

it stores waveforms as jpeg (64 mb memory)

I don't see real cursors but looks okay... what do you guys think? overpriced toy?

 

A 100MHz 500MSa/s handheld scope for less than $100? Very sure that will be a toy.

Big brand handheld scopes like R&S ScopeRider start at > $3k. Even the Siglent SHS800, pretty much the bottom end for a handheld that's not just a toy, starts at $465 for the 60MHz variant.

Anything lower than that and you're solidly into toy territory as far as handheld scopes are concerned.

A potential alternative could be using a cheap bench scope like the Rigol DS1054z or Siglent SDS1202X-E in combination with a 12V to 120V inverter.

 

Wait... that gives me an idea... I have a Hantek bench scope... there's no way it needs the 120V so skip the inverter ... If I bypassed the bridge rectifier and voltage regulator I might be able to run in on a decent lithium battery pack and a regulator, my guess is it will work on 5VDC... the scope is very light, looks like I might have fun project to turn my bench scope portable.

The bypass will requiring switching or at the least reverse protection for onboard regulation.

Then adding a plug should make it easy on the go... don't want to deal with headaches of balancing and charging lipo.

The only concern I have is about grounding but it should be fine for my project.