Hi Dan,

Thanks for stopping by.

An attenuator reduces the input voltage to the scope by the amount of the multiplier.  For example, a 20:1 attenuator reduces the voltage by a factor of 20 so that a 400 volt signal is reduced to 20 volts for the scope.  The scope vertical scaling is adjusted so that the scale displayed shows the actual voltage.

PicoScope has a maximum input of 20 volts and that is the top of the scale on the screen.  Using the 20:1 attenuators, included in the kit, allow you to observe up to 400 volts on the screen.  These are used when sampling ignition primary or injector signals which have high inductive spikes.  The Autonerdz Master kit includes two of these so you have one for each channel when needed.  The scaling is simply adjusted to tell the scope that you are using the attenuator so the screen reflects the actual voltage sampled.

Here is an example:



Note the 5 volt voltage scale is displayed as 100 volts.  (5x20).  Both attenuators were used to display two injectors.

Hi Neil,

Good question.  The PicoScope is quite tolerant of this.  In fact, when I was first testing PicoScope for myself, I deliberately tried to break it by doing just that.  I looked at a primary with a spike of over 400 volts.  Well, years later, it's still working great.

Here is a small portion taken from the PicoScope Tips document included with each Master kit:
__________________

Letting Out The Smoke

Do not measure main supply voltage with the Pico. This is clearly stated in the documentation.   Here is what the Pico boys had to say on this subject:

"The basic ADC212 as you know will measure to +20V. The overload protection is quoted at 100V, but in reality will take at least 200V. It will also withstand short spikes of higher duration (eg primary ignition, injectors etc without the x20 attenuator).

What will blow it up - secondary ignition will. Direct connection to mains 110 / 220V will as well. This is less to do with the voltage than with grounding. As with most scopes, the outer shell of the BNC is usually grounded (through the PC in our case). Connecting a lead across mains effectively connects neutral to earth - this is what damages the scope, not the high voltage. Our advice on mains is use a isolating differential scope probe -

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

With the x20 adapter, you can measure up to 400V, transient spikes at least double this should be OK. "

Automotive voltages are not a problem provided you don't plug the secondary directly into it :-p

When powering the PicoScope on vehicle power, be certain of your connections and do not place a ground lead on a power source by accident.  This will allow the power to find a path to ground through the PicoScope.    It is the users responsibility to take care when hooking up.  Smoke can be expensive.

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We have had one in our group damaged by placing the BNC grounds accross a battery supply.  I was able to put the smoke back in it, but was lucky there was not serious damage. 

These issues are not peculiar to PicoScope.  Placing the grounds of other scopes accross battery supplies kills them just as well.  Also measuring mains with scopes that are plugged into the wall for a power supply will likely toast tham nicely.

Taking care with hook ups is essential with any such instrument.  Occasionally forgetting the attenuator, while not advisable, will not likely hurt a thing.   8)

Hi Matt,

Yes, it's very configurable.  You can select 1x, 10x, 20x, or 100x for a channel.  You can also build a custom range to suit.  You can tell PicoScope that Xmv equals Y units.  Those units can be KV, amps, pounds, or whatever and are displayed on the vertical axis.  Here is a shot of the the custom range dialog:



The secondary attenuation is 10,000:1.  We have told PicoScope that -900mv = 9kv and 100mv = -1kv.  We have 100mv per 1000v.  The negative 900 turns the secondary trace 'right side up' for conventional firing.  If we wanted a 12kv range, we would simply change the numbers to -1200 12 and max value 12.

If you don't like any of the provided ranges you can just make one of your own.  It's a little different at first, but not difficult.  Building custom ranges is an essential PicoScope skill.   

Too much information, I know. 

this discussion reminds me of something I was going to do with my modis but decided against it,I had a bum injector on a ford powerstroke 7.3 tdi and I wanted to amp probe them to see which one it was but I was afraid to trigger off voltage control for cyl one because of the extreme voltage on these I guess if I had an attenuator I could put my mind at ease,I dont do to much with diesels so was in unfamiliar territory with what I was trying to do      ...Any input on that particular test from someone who is more experianced than my self on diesels would be appreciated