# 16 analog channel oscilloscope for hobbyist?

#### DMahalko

Joined Oct 5, 2008
189

Ron

#### Irving

Joined Jan 30, 2016
3,187
Your whole premis of powering a wheelchair from an SMPS is wrong. The use of an onboard generator to charge batteries and/or power wheelchair has been tried and dumped many times. As a permanent user of a highly customised wheelchair myself - with a 40+ mile range that recharges in under 3h - as well as an experienced electronic and mechanical engineer I know its not practical to power a wheelchair that way. The ActionTrack chairs are hopelessly optimistic about 'a 7 mile' range with their 400kg+ all-up-weight, AGM batteries, puny Curtis controllers and massively inefficient drive train.

You want solutions? If, unsurprisingly, more range is your requirement, the solution is to junk the AGM batteries and onboard charger. Happy to tell you more, if you're prepared to listen.

#### bassbindevil

Joined Jan 23, 2014
631
Here's 8 channels, but you're not going to have much resolution with 8 traces on the screen at once.
https://www.pcbway.com/project/shareproject/8_Channel_Voltage_Multiplexer_for_Oscilloscope.html
I don't know if it would be better to add a mux to an ADC or use four 4-channel I2C ADCs, like these at Adafruit. (You can probably find generic versions elsewhere for less money.)
Analog's fault-protected analog mux chip:

Maybe the solution is to rewind the generator to produce 28V... or replace it with a DC motor that can both start the engine and work as a generator. I thought that might be something that existed for military applications, but all I found was a portable 2kw unit that weighed about 150 pounds.

Joined Jan 15, 2015
7,074
On another note these units feature a battery charging output for charging 12 volt automotive batteries. This is covered on page 34 of the owners manual. The schematic (block diagram) can be found on page 71 of the owners manual and I seriously doubt applying three phase AC to the main stator winding is going to do anything. Not without anything applied to the excitation winding. All of this simply is not practical and I have to agree with Irving in post #14.

Ron

#### DMahalko

Joined Oct 5, 2008
189
This is what you have. You have a tiny 900 watt generator which uses an inverter. Seriously if you want electric start the most viable solution would be to upgrade to a larger unit like the EU3000i series.
All About Circuits seems to be famous for topic drift, so I suppose we can keep talking about this here. No forum mod has yelled at me in private messaging.... yet...

Dragging around more weight is going to be counterproductive.
EU1000i dry weight - 29 lb
EU3000iS dry weight - 130 lb

The EU3000iS starting is not fully automatic as it has a manual choke and fuel valve.
The fuel valve should be closed when the engine is not running.
So it would still need modification to be started from the seated chair position, though not as extensive as the small generator.

#### DMahalko

Joined Oct 5, 2008
189
On another note these units feature a battery charging output for charging 12 volt automotive batteries. This is covered on page 34 of the owners manual. The schematic (block diagram) can be found on page 71 of the owners manual and I seriously doubt applying three phase AC to the main stator winding is going to do anything. Not without anything applied to the excitation winding. All of this simply is not practical and I have to agree with Irving in post #14.
The DC charging circuit of the EU1000i is load-limited to 8 amps, probably 15 volts charging, so 120 watts maximum output, while the 3-phase is rated for 900 watts continuous, 1000 surge. The DC charging output not useful and can be ignored.

I expect the excitation winding needs power while the 3-phase is driven as a motor. If a motor/generator doesn't have permanent magnets then it will have a stator field coil. I don't see anything surprising about that.

While running with a 900 watt rated maximum load, determine the operating characteristics of the volts/amps being supplied to the excitation field coil and the output volts/amps of the 3-phase alternator windings.

#### dl324

Joined Mar 30, 2015
15,439
All About Circuits seems to be famous for topic drift, so I suppose we can keep talking about this here. No forum mod has yelled at me in private messaging.... yet...
It's your thread; you can talk about anything you want as long as it isn't a prohibited topic. If you want to keep it on topic, you can report posts you feel are taking it off topic.

Joined Jan 15, 2015
7,074
The DC charging circuit of the EU1000i is load-limited to 8 amps, probably 15 volts charging, so 120 watts maximum output, while the 3-phase is rated for 900 watts continuous, 1000 surge. The DC charging output not useful and can be ignored.

I expect the excitation winding needs power while the 3-phase is driven as a motor. If a motor/generator doesn't have permanent magnets then it will have a stator field coil. I don't see anything surprising about that.

While running with a 900 watt rated maximum load, determine the operating characteristics of the volts/amps being supplied to the excitation field coil and the output volts/amps of the 3-phase alternator windings.
Yes, I agree and the 12 VDC charging circuit also is not regulated or monitoring battery charge. I also agree somewhere out there a formula may exist to get from the max output of 900 Watts to what excitation voltage and current is needed.

Those little Honda units are really nice units. They are quiet and efficient. I just don't see an easy way to add an electric start to the model you have. Just my opinion on the practically of doing it. The larger units have the electric start feature but not the little units. You may be able to run the unit under a full load and while running look at the excitation voltage and current and even with that known I just do not see trying to use 3 phase AC applied to the stator to use the alternator as a motor starter as going well. Since the manuals are available online if you look at for example an EU3000 unit the lowest electric start in the series the electric start is a DC motor. They use a separate DC starter motor similar to other electric start generators. A high torque DC starter motor like I find on my motorcycle.

You can pursue this but I just do not see it ending well. I do wish you the best of luck with the endeavor.

Ron