oscilloscope for tapping 12V alternator

[0101byte]

I'm looking for an oscilloscope to check on car's battery (12V) or alternator (14V) DC voltage. The main purpose is to see how stable is the voltage. I have many voltage stabilizer so i would like to see which 1 works best and if things gets better if many stabilizer are installed in parallel, etc...

I'm looking at picoscope 2204 & 2205, but since i have not involved in oscilloscope before, can anyone tell me what spec do i need to achieve the purpose?

Sampling rate
Bandwidth
Vertical resolution
?

any other brand suggesetion?

 

[BioniC187]

Most scopes are about 400Mhz. Even scopes that are 20 years old or so. So any scope would work for you provided it has a sample rate of +300Mhz. All you are checking is the stability, the variation in the voltage, so it will be fine

 

[0101byte]

Most scopes are about 400Mhz. Even scopes that are 20 years old or so. So any scope would work for you provided it has a sample rate of +300Mhz. All you are checking is the stability, the variation in the voltage, so it will be fine

Yes, i'm testing the DC ripple current to be more precise. You mean i will need at least 300 Mega sample / second scope ?

 

[BioniC187]

No, i am saying most scopes are like that. That is 400 million per second. And the pulses from the alternator will be far less, so any scope in such a range will be more than sufficient

 

[0101byte]

View attachment 67669

Which one will be good to view the ripple ? These digital scopes are not so high as 400 mhz.

 

[JimB]

Most scopes are about 400Mhz. Even scopes that are 20 years old or so.

A sweeping generalisation and completely wrong!
Many modern scopes have bandwidths much less than 400Mhz.

So any scope would work for you provided it has a sample rate of +300Mhz.

What!
A car alternator is a DC system, the voltage is around 14vdc when charging with some AUDIO FREQUENCY AC ripple due to the rectification of the alternator output.
You do not NEED a scope with sample rate above 300Mhz!
And why not use a good old analogue realtime scope with a cathode ray tube?

Just about ANY scope would be good enough for this.
Although having said that, I am not sure what 0101byte is trying to prove with this test.

JimB

 

[0101byte]

Hi JimB,

there is a little mis understanding, what i want to measure is the voltage when car is stopped i.e. 12V and the voltage when car engine is running 14V (I called this as alternator voltage). Basically both are DC just with different voltage.

What i want to test is when we plug in a voltage stabilizer into a car (Those builded with capacitors), i want to be able to visualize it using oscilloscope as in "how stable is the voltage" because voltage stabilizer stabilized the voltage as the name suggest right?

In ideal case, a stabilized voltage which has less ripple and this is what i want from an oscilloscope.

My only choice is PC oscilloscope where i want to save the data to build a database. So say i chose this scope with these specs, do you think it can serve me well with my desire purpose ?

Picoscope 2204:
Bandwidth: 10 MHz
Sampling Rate: 100 MS/s
Vertical resolution: 8 bits

For my purpose, can somebody tell me is sampling rate more important or vertical resolution?

 

[Nigel Goodwin]

What i want to test is when we plug in a voltage stabilizer into a car (Those builded with capacitors)

What exactly are you trying to do? - do you have a problem with the car electrics? - those sort of items are generally pretty useless. If you've got a big amplifier in the boot, then sticking a huge capacitor in the boot close to the amplifier will give a small benefit, as it helps to compensate for losses down the long cable from the battery.

 

[0101byte]

What exactly are you trying to do? - do you have a problem with the car electrics? - those sort of items are generally pretty useless. If you've got a big amplifier in the boot, then sticking a huge capacitor in the boot close to the amplifier will give a small benefit, as it helps to compensate for losses down the long cable from the battery.

As what you said useless, how useless is it? i want to see from the scope to tell it's useless. And also if i have the scope, i'm flexible to even test out the huge caps like you said too right?

Please what spec scope is suitable for me? Pico tech is recommending me 4000 series which is very expensive, i do not want to spent so much just to test the voltage ripple.

 

[Nigel Goodwin]

As what you said useless, how useless is it? i want to see from the scope to tell it's useless. And also if i have the scope, i'm flexible to even test out the huge caps like you said too right?

Please what spec scope is suitable for me? Pico tech is recommending me 4000 series which is very expensive, i do not want to spent so much just to test the voltage ripple.

The cheapest possible will do, the application is VERY low specification, but I feel you're just wasting your time - how will you even tell what is good and what isn't?. Will a few mV of ripple make any difference? - if you can't obviously hear the difference then it's pointless.

 

[cowboybob]

0101byte, welcome.

Gonna sound like a broken record here, but....

Yoy might want to try this scope.

View attachment 67675

All the newer digital scopes are a little harder to learn how to use than the older CRT types, but well worth the effort in the end.

This scope will easily display what I think you're looking for and, if you add a SIM card, it'll hold "snapshots" of previous traces for comparison to current traces.

And they are very portable, charged by USB and inexpensive ($73 USD) .

 

[kinarfi]

I've been real happy with my Hantek DSO2150
The Battery acts like a capacitor and helps stabilize the out put ripple of the alternator and the use of an inductor in the output lead of the alternator would help some too.

 

[MikeMl]

Let me guess. High power amp in the trunk. Have alternator whine in the audio. You think that "filtering" will cure the problem. But you never heard of a ground-loop.