Can you tell me how to test this handheld oscilloscope ?

the video you posted basically has detailed troubleshooting procedures and waveforms and I even suggested some tests to do

Take out the CD 4049 chip and just concentrate on the 555 output. Pin 3 and ground.


Joined Mar 30, 2015
I just tried probing a 555 timer with my scope like yours that I got from Ali Express. It worked with a 1X or 10X probe. Even just the alligator clips that came with it worked, didn't notice it loading the timing circuit.

Thread Starter


Joined Mar 1, 2017
Finally got a reading.
Thanks for all the guidance.

As far as what was expected......
I was expecting 60-80v bursts at approximately 1khz
Not sure this will do anything as a "desulfator" at that low voltage.
Voltage at the battery terminals is 13.45v

The great news is that it appears my little O-Scope works.


Thread Starter


Joined Mar 1, 2017
Great! Can you share with us what you changed to get it working, so we can help the next person better?

I'm not exactly sure.

The most likely change was building a totally different circuit board.
I had 5 of the same circuit boards on hand and assembled another.
So my best WAG is that the original board had a bad component....even though I could not find it. Maybe the NE555 or CD4049
(Oddly, I had changed them both and it didn't help)

I had checked all the resistors, diodes and the capacitance and ESR of the capacitors.
Maybe the inductance of the choke was way off? (It came from Mouser so I doubt it)

Essentially, I'm not exactly sure Bob.

Thread Starter


Joined Mar 1, 2017

REALLY appreciate the time you took to help me with those indepth posts. Still reviewing and referring to them.
You gave me quite a bit of information to chew on.

Thank you again.


Joined Oct 8, 2019
Fault diagnosis takes many forms beyond the compulsory first set of 'thou shalt check for voltages' then with a scope always the primary sanity check is the probe compensation 1KHz output.
For pulsers such as these the gate of the MOSFET would be a good place to start and then work backwards into the timing circuit to ensure it's oscillating as intended.
The battery desulphators I played with nearly 2 decades ago were very simple circuits and with a little effort could be tuned for 7A 70V outputs where the ferrite quality and type was instrumental in getting good results however a current probe was required to get the best from DIY inductors so to not have the MOSFET ON time lead to inductor saturation and substantially reduce efficiencies.
To have a battery desulphator that's only powered but the battery it's pulsing improve the battery OC voltage overnight is a very satisfying result.