Moving the verticle position of the waveform on a Hantek 1008C

I'd like to see some waveforms at higher vertical detail, but increasing the resolution beyond a certain point makes the waveform go off the top of the screen, and the little tab on the left side used to manually position the waveform is already all the way at the bottom.

Is there a way in the Hantek 1008C software to bias the vertical position of the waveform on the screen so that zero volts is off the bottom of the screen?

In some cases you could ac~couple the signal just like you would to see ripple voltage. This works for example on a map sensor to view the intake pulses of each cylinder....

Other than that I don't think.

Yes AC coupling is what you want but it is one of the limitations of the Hantel 1008 is the ac coupling menu option is greyed out isn't available. But all is not lost all you need to do is make up a test lead with a capacitor in series to block the DC.
This is a really simple trick to do all you are really doing is putting a capacitor between the + wire of the scope and the voltage you are looking at. The capacitor blocks all the DC voltage part of the signal and leaves the AC wave form ---- good for cranking compression, alternator ripple and many other things.
I while back I posted a set of instructions on how to do this but I can't find the post it may have been in the old forum will I will look out for the pictures and spec of capacitor I used.

Andy.MacFadyen wrote:

That's ingenious.

Can you give some spec's on the capacitors requirements?

Do you have to be concerned with the capacitor charging up & zapping someone or something?

My scope does AC coupling, but I find this to be an interesting workaround if it didn't.

Thanks

The capacitor was a small poly polyester film capacitor I used a 400v voltage rated type. I cant recall capacitance probably 0,47uf.

Here are a couple of pictures of the test lead with DC blocking capacitor it is encased in epoxy to insulate and protect it.

As someone else (Juiced105) pointed out in a different thread, AESWave has a couple of solutions.

Inline banana adapter: www.aeswave.com/AC-Pass-Filter-Adapter-p9178.html

And a real nice insulated cable: www.aeswave.com/AC-Pass-Filter-Test-Lead-p8578.html

For $17.00, with free shipping, the banana adapter seems like the way to go.

So, my box of capacitors finally arrived, and I tried a few out to see their effects. The first I tried were a 47uF and 4.7uF and you can see here that it took a long time for them to pull down the voltage:



Then I tried a 0.1uF cap and it pulled down the voltage quite a bit quicker:



It still took about 10-15 seconds though, so in the future I'd probably use something allot smaller, like maybe a 0.01uF cap.

Still I got pretty good results using it on my alternator voltage which you can see here:

Just in case anyone is interested, I found a company, autoditex, which sells a bnc 1:1 AC coupling adapter:

autoditex.com/ac-coupling-adapter-100.html

There's a page on their site which lists local sales reps in various countries.

OK, so I made a little video on how to make your own ac coupling adapter:

SailorBob wrote: It still took about 10-15 seconds though, so in the future I'd probably use something allot smaller, like maybe a 0.01uF cap.

Going with the smaller is better theory I tried a 0.001uF I found in an old satellite receiver box. This was taken using a power supply set at 14v and the laptop plugged in. That's why the trace is noisy.



There was also a tiny 0.000068uF cap on the board so I tried it too. It really clamped the peak voltage and shortened the decay time. This one is using a battery as power source and with the laptop running on internal battery.



And this is what the laptop being plugged in was doing to the yellow AC coupled trace.

Made up an AC coupled lead with the 0.001uF Cap. Hopefully the adhesive lined head shrink will hold it together.......





Now for testing. Purple traces are the AC coupled lead connected across the battery. Green are "current".

First off relative compression. Maybe this cap is too small to get a useable relative compression waveform??



Then I started the truck and got alternator ripple. The lead seems to be working really well for this test.