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Small Cabin Forum / Off Topic / Dirt Cheap Oscilloscope
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paulz
Member
# Posted: 25 Nov 2021 08:42
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Wondering if one of these will determine cycles and wave form on generators and inverters.

https://tinyurl.com/ja2n64ba

Description :
- DS213 is a "5-track, 4-wave line" digital storage oscilloscope for general-purpose electronic engineering task and it is based on ARM Cortex M3 core. DS213 uses FPGA to manage external ADC’s control and data cache mode. It provides 4 application partitions for loading and upgrading up to 4 different application firmware. It also has built-in 8MB USB flash drive for storing waveforms and upgrading system firmware. The oscilloscope code application layer is open source, and users can develop oscilloscope firmware according to their needs
Feature :
- Mini size, light weight, portable and handheld;
- It can store waveforms, making waveform analysis clearer and more effective;
- Multiple trigger modes, support Ascend/Descend Edge Trigger, Positive/Negative Pulse Trigger, and Logic Trigger;
- Powerful ability to process waveforms, it can automatically measure parameters such us voltage, frequency and pulse width.
Specification :
- CPU: ARM Cortex M3
- FIFO & Control: FPGA
- ADC: HWD9288-100
- Analog Channels: 2 [CH_A] [CH_B]
- Digital Channels: 2 [CH_C] [CH_D]
- Operation Channel: INV [CH_A], INV [CH_B], [CH_A]+[CH_B]、 [CH_A]-[CH_B]、[CH_C]&[CH_D]、[CH_C] | [CH_D]
- Vertical Sensitivity: 10mV-10V/div (1-2-5 STEP) (using X1 probe)
100mV-100V/div (1-2-5 STEP) (using X10 probe)
- Vertical Resolution: 8 bits
- Sample Memory Depth: 4 channels, 4*4K
- Coupling: DC, AC
- Max Input Voltage: ±40Vpp (using X1 probe) ±400Vpp (using X10 probe)
- Trigger Types: Ascend/Descend Edge Trigger Mode, Positive/Negative Pulse Trigger, Logic Trigger
- Trigger Mode: Auto, Normal, Single, Slow
- Trigger Source: [CH_A] [CH_B] [CH_C] [CH_D]
- Signal Source: Square Wave: 10Hz to 8MHz, in total 20 shifts and 3 Vpp Signal Sources;
- Sine/Triangle/Sawtooth Wave: 10Hz to 20MHz, in total 11 shifts and 3 Vpp Signal Sources
- Storage: built in 8M USB disk
- File Types: BMP, BUF, CSV
- Auto Measurement Types: Signal sequence/cycle/duty ratio, peak voltage/virtual value/max value/min value/average
- Cursor Measurement: Time value, Amplitude value
- Display Modes: 4 wave lines: Line 1: [CH_A], HIDE
Line 2: [CH_B], HIDE
Line 3: [CH_C], REC_1, REC _2, REC _3, REC _4, HIDE
Line 4: [CH_D], [CH_A]+[CH_B], [CH_A]-[CH_B], [CH_C]&[CH_D], [CH_C] | [CH_D], HIDE
- Sampling Mode: Real-time Sampling
- Sampling Rate: 100M Sa/s
- Battery: 1000mAh
- Size: 99.5mmx58.5mmx13.5mm
- Weight: 129g (with battery)
Certificate: CE, FCC
Package included :
- 1 x DS213 Digital Oscilloscope
- 1 x X10 Probe
- 1 x X1 Probe
- 1 x USB Cable
- 1 x Screw driver
- 1 x Cover Bag
- 1 x User Manual
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Whiskerbiscuit
Member
# Posted: 25 Nov 2021 14:00
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The actual oscilloscope itself from that ebay link is $289....I don't know much about this type, is that dirt cheap? Unless it's really important to have a miniature handheld one, seems to me you could get find a real solid-state workbench oscilloscope for a lot less. I paid $50 for a B&K one a few years ago. The $8.76 price is only for a red rubber case.

paulz
Member
# Posted: 25 Nov 2021 17:42
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Ah OK, oops. They publish all the specs like you're getting the whole thing.

There is an ad or Craigs list near me for a scope. I know nothing about these, does this sound OK?

Tektronix 5111 Storage Oscilloscope - $50

Tektronix 5111 Storage Oscilloscope with 5A15N, Amplifier, 2 5A18N Trace Ampl. will sell Ampl. sep. asking for all. well take ?? offer, trade for ???? cond. un-known. Oscill. Lites up with center dot.

ICC
Member
# Posted: 25 Nov 2021 21:14
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What would you use it for?

paulz
Member
# Posted: 25 Nov 2021 21:49 - Edited by: paulz
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To look and sine waves and frequency, if it would do that. Also the car guys use them to isolate misfires, but again I think that takes a special one made for it.

ICC
Member
# Posted: 26 Nov 2021 00:09
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Yes it can do that but it isn't a tool that can be used to get much useful information unless the operator knows what they are doing.

https://www.circuitspecialists.com/blog/what-is-an-oscilloscope/

The Tektronix for sale is old according to a friend. Old CRT tech, not digital, was v good when new, could still be working well

travellerw
Member
# Posted: 26 Nov 2021 09:08
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If that is all you want to do, then the cheap chinese scopes on Amazon will work. About $40.. They can easily measure a 60hz wave, plus pretty much any sensor in a car.

This is just one example. There are tons of them.

https://www.amazon.com/Quimat-Oscilloscope-BNC-Clip-Assembled-Finished/dp/B07QML4LJL/ ref=pd_sbs_3/142-5139973-1324063?pd_rd_w=oTz1W&pf_rd_p=3676f086-9496-4fd7-8490-77cf7f 43f846&pf_rd_r=EKTW1AMEJ1XQBAW4G16E&pd_rd_r=9a8237a6-1129-4ca4-9eba-51d48e4f059f&pd_r d_wg=a7sxP&pd_rd_i=B07QML4LJL&psc=1

paulz
Member
# Posted: 26 Nov 2021 10:44
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Looks good, I'll get one. Thanks!

paulz
Member
# Posted: 9 Dec 2021 19:02
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My $30 oscilloscope arrived a few days ago. Not a simple instrument, but through sufficient caffeine ingestion and late night You Tube videos I've learned enough to A) not blow it up and B) look at some sine waves.

The nice even one is a FSW inverter, also matches what I got off the grid back at the house. The square one is a MSW inverter. The other two are non-inverter generators.

And, as luck would have it, my only inverter generator died on me yesterday. No spark. Coil checks OK, looks like no pulse voltage reaching it, could be from the myriad of electronic doodads. On the bright side my solar kicked in pretty well while we were gone, and I bought a new inverter generator that will be here end of the month.

I'm just not sure what I'm getting out of the non-inverter generators is clean enough to run the Meawell power supplies to charge my battery bank. I also have an Onan LP RV generator I will try tomorrow.
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travellerw
Member
# Posted: 9 Dec 2021 20:00
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Non inverted generators need a load to show their true sine wave. They usually need a fair load to show it (like 300w or so).

As to your generator. There are 2 coils. The main spark coil and a "trigger" coil (sometimes called a pulser coil). The trigger coil feeds to the CDI and is responsible for the timing of the spark. If the trigger coil dies, no spark.

We test the 2 coils and if both test out OK, then we switch the CDI.

paulz
Member
# Posted: 9 Dec 2021 20:31
Reply 


OK thanks, I'll plug something in when I test tomorrow.

paulz
Member
# Posted: 10 Dec 2021 17:48
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Got the Onan fired up today, took a bit of effort, hasn't run in a couple of years and getting the LP flowing took some effort. It was worth it however, the sine wave looks great, with and without powering a bread toaster.

Can't say the same for the old gas generator. I haven't played around looking at voltages and cycle times but if you look at the triangulated picture in the above post, it's longer than the others. And here it is with the toaster going. I don't think it's running at 3,600 rpm like it's supposed to, loaded or not.
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FishHog
Member
# Posted: 11 Dec 2021 07:53
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That’s cool Paul. Gives a great visual as to why some electronics don’t like dirty power

gcrank1
Member
# Posted: 11 Dec 2021 10:49
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Looks like it might have already paid for itself

paulz
Member
# Posted: 11 Dec 2021 16:47
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Thanks, yeah I'm pretty satisfied. Bit of a gamble, although an inexpensive one, as it took some studying for my relatively minor electrical knowhow to get it working.

If anyone is thinking of getting one, go directly to this video. It's an hour long but he does an excellent job of explaining how everything works in easy to understand terminology.

https://www.youtube.com/watch?v=FqfQyD3AMYA&ab_channel=youtuuba

paulz
Member
# Posted: 11 Dec 2021 17:04
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Quoting: travellerw
As to your generator. There are 2 coils. The main spark coil and a "trigger" coil (sometimes called a pulser coil). The trigger coil feeds to the CDI and is responsible for the timing of the spark. If the trigger coil dies, no spark.


Two primary wires come out of the ignition coil. One is grounded. The other runs into this gizmo, is that the CDI? I have changed them on dirt bikes before and they only had a couple of wires. The wires on this run everywhere it seems.
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travellerw
Member
# Posted: 11 Dec 2021 17:39
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Quoting: paulz
Two primary wires come out of the ignition coil. One is grounded. The other runs into this gizmo, is that the CDI? I have changed them on dirt bikes before and they only had a couple of wires. The wires on this run everywhere it seems.


Hmm are we talking about the coil that goes to the spark plug (usually has one wire coming in the bottom, and then the spark plug wire out the top). That would be the main coil. Usually the wire coming out the bottom goes to the CDI. The trigger coil is a smaller coil mounted to the block next to the flywheel, a magnet flys past it and "triggers" it. They usually have 2 wires coming out that go to the CDI.

CDI's can have many wires as they usually control low oil shutdown, over revving, ect.

Now after all that, lets do the easy thing.. What is the make and model? We will see if we can find a wiring diagram and OHM values for 2 coils (and where to test them).

paulz
Member
# Posted: 11 Dec 2021 18:01 - Edited by: paulz
Reply 


Quoting: travellerw
Hmm are we talking about the coil that goes to the spark plug


Yes, spark plug coil. I have not taken the flywheel cover off yet, looks like I have to pull the engine off the chassis. The red wire (becomes yellow/green at connector) runs to ground, the blue goes to the box in the other photo.

It's a Honeywell 1000i.
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travellerw
Member
# Posted: 12 Dec 2021 12:00
Reply 


Quoting: paulz
Yes, spark plug coil. I have not taken the flywheel cover off yet, looks like I have to pull the engine off the chassis. The red wire (becomes yellow/green at connector) runs to ground, the blue goes to the box in the other photo.


FIRST - Replace the spark plug. Its the easiest thing and I have seen many generators fixed by just a new plug!

Then, use a multimeter and test between the red wire and inside the spark plug boot. It can vary between manufacturers but between about 6-20ohms is about right. (Spark plug boots have resistors in them to help with electrical noise, the resistance varies wildly with manufacturers).

After that, I would check the resistance of the actual on/off switch. Ensure its a solid connection when switched on and breaks when off.

Next, check the oil and then disconnect the Low Oil Sensor by disconnecting the two wires that run from the base of the engine where the oil sensor is located and then check for spark. If you have a spark then the Low Oil Sensor has failed (Generator Guru instructions).

Its very hard to find any information about that unit online, even though it looks like its sold under MANY brands. It looks like this unit has no pulser (trigger) coil and everything is controlled by the main coil and CDI. Generator Guru is the only place I could even find that stocks the CDI.

Hopefully this gets you going down the right path.

paulz
Member
# Posted: 12 Dec 2021 13:03
Reply 


Thanks Trav. I'm an old car mechanic so I have some ignition understanding (with points and condenser mostly). The coil has about 1 ohm of primary and 7k of secondary resistance, think it's OK. I have held the bare plug wire in my fingers while pulling the cord, nothing. I put a DVM on the blue wire coming from the CDI (the box in the red circle above) and pulled the cord, no change in voltage. I haven't been able to find the oil sensor, usually it's conspicuous on the Hondas, it's not on the block on the two sides I can see, might be under the flywheel cover, and I can't tell which wires lead from it. I did drain and put in fresh oil, no help. The on/off switch wire runs to ground, must ground the ignition (magneto?). The switch tests good and I have tried it unpluged. I'd love to fix it, was running just perfectly, don't know what happened. I'll leave it on the work bench for awhile and keep pulling the cord when I walk by hoping it fixes itself. I also took a heat gun and warmed up the circuit board to maybe help a weak connection, no help.

The coil, as you can see, looks like the type that the flywheel passes under, with a small air gap, to induce voltage, but obviously it's on the outside away from the flywheel. Odd, not sure what generates the juice. I guess these inverter gennys are like newer cars, much more electronics to deal with than the older stuff.

But I now have an Onan generator going I can use for charging my cabin bank, bit of overkill, and I bought one of those cheopo Sportsman 1000i inverters Tractor Supply had on sale at Thanksgiving for $180. It's being brought down by a friend from Washington state, not sold in California where I'm at (Cal EPA thing), have it at Christmas. So I should get through winter one way or another, until the sun clears the tree line again. I have been getting modest solar charging, 3-5 amps, enough to balance the load, during the day, but only several hours. Last night I turned off the fridge, packed the cooler and stuck it outside, 40F or so. That cuts the load down substantially.

Thanks again for the effort. I have a hard time pitching things that can be fixed. And when I do, it's usually electronics.

travellerw
Member
# Posted: 13 Dec 2021 10:36
Reply 


Quoting: paulz
The coil has about 1 ohm of primary and 7k of secondary resistance, think it's OK


So based on that, I would say the coil is good. However, coils can test good and still be bad (my gut says this one is good).

One question! Did it die while running and wouldn't start again, or did you shut it off and it never started again?

Based on your description of ZERO spark (holding the wire.. I too like to live dangerously ;) ), CDI would be the #1 culprit. BUT... The low oil sensor could be the issue too. Unfortunately all the information online is for the 2000W version and it looks to be very different. So finding the low oil sensor (its possible the 1000W unit doesn't have one), might be a little difficult. If it has one, there will be a wire coming out of the block that is either in circuit with the switch, or goes directly to the CDI. Once you find it, you can simply unplug it to disable it!

The CDI is $78 online. Not sure if its worth the risk to buy it. Since you are doing the work, I would say yes. If you were paying someone, then no way.

paulz
Member
# Posted: 13 Dec 2021 12:08
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Quoting: travellerw
I too like to live dangerously ;)


Lol, after so many years of wondering is the plug bad, the terminal, now I just grab the wire.

I just finished messing with it a little. That's what happens when I leave something broken on the work bench, curiosity eventually prevails. The engine came out easily, the oil sensor was dead at the bottom, one wire to ground and the other wire I had suspected was it and had disconnected, so that's not the problem.

Found the pulse dingus, has about a .020 air gap to the flywheel at the trigger. There is one wire coming from it, also leading to that black box. Can I test it for on/off with ohms or is there another way? I can also see many coil windings behind the flywheel, and feel magnetic pulses when turning it over slowly. Two sheaths of wires come out of there, one has heavy gauge going to the big board with capacitors and what not, probably the generator coils. The other sheath has small gauge wires going to the same connector as the pulse dingus, so maybe they are where it gets its voltage.

It was running perfectly, shut it off, never able to restart.
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gcrank1
Member
# Posted: 13 Dec 2021 13:37
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My 'newer' motorcycles with cdi ignition are shut off by the ig switch or kill switch (and the other safety switches) by grounding the cdi. Not at all like the old points/cond/coil ignition that the main switch energized off the battery +; ie, dont ever send any + into a cdi!
So, after some die-outs on cdi bikes I found to look for anything grounding that cdi shut-down. One bike had the key switch go wonky from vibration.
Most other stuff, mowers, etc, the safety switches are just unplug to bypass. One lawn tractor 11yrs old has all those now disabled as they failed one by one.....

paulz
Member
# Posted: 13 Dec 2021 15:27
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I put an ohm meter on the pulse generator, it has about 100 ohms, then putting it near the metal tang on the flywheel changes it to something lower, so it is doing something.

The other part in question looks just like this Honda 'spark unit', might even work but I'll look for a matching part number.
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travellerw
Member
# Posted: 13 Dec 2021 17:57
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Quoting: paulz
I put an ohm meter on the pulse generator, it has about 100 ohms, then putting it near the metal tang on the flywheel changes it to something lower, so it is doing something.


Unfortunately each pulser coil is made a little differently. The ones I'm familiar with have about 147 ohms of resistance.. but I would say 100 ohms is probably ok. They really just send a trigger pulse to the CDI so it dumps a pulse into the main coil at the right time.

Although people think a CDI is a magical black box, they are really quite simple devices. Basically just a capacitor with a trigger circuit. The capacitor charges up and then dumps that charge into the main coil when the trigger hits. We have actually put CDI units from quads/dirtbikes into generators where we couldn't get the actual part. However, some manufacturers include other functions in the CDI like low oil shutdown and over RPM protection. So each CDI can have a different pinout (even if they look identical). For $38 it might be worth the risk.

Based on your description, my gut says CDI. Its usually the CDI when you shut it off and it won't start again. Coils usually fail while running and shut the unit down!

paulz
Member
# Posted: 14 Dec 2021 11:34
Reply 


Quoting: travellerw
Based on your description, my gut says CDI. Its usually the CDI when you shut it off and it won't start again. Coils usually fail while running and shut the unit down!



I found a wiring schematic for the Honda EU100i, this Honeywell appears to be a direct ripoff, all the wiring jives. So I found the wire coming from the exciter winding going to the CDI (they call it a Spark Unit) and tested it while spinning the engine. I'm getting about half a volt AC, I can't spin it very fast just holding the flywheel. Anyway it is putting out something.

https://www.manualsdir.com/manuals/95562/57/honda-eu1000i-page57.png

Also found a replacement unit for the Hondas for $27, again looks the same, thinking about trying it. But it would be good to know if one of the other things, inverter unit, overload indicator, connected to it was not the problem. Doubt I can do any testing on that that though.

https://www.partspak.com/productcart/pc/Honda-30400-Z07-013-Spark-Unit-New-30400-Z39- C91-p351245.htm

travellerw
Member
# Posted: 14 Dec 2021 12:09
Reply 


Quoting: paulz
But it would be good to know if one of the other things, inverter unit, overload indicator, connected to it was not the problem. Doubt I can do any testing on that that though.


I have fixed a quite a few Hondas.. Those items are completely independent of the spark system. The inverter and overload protection will only disable the AC when somethings goes wrong, but the unit will still run(usually with a blinking light to indicate a fault). If the inverter dies, the unit usually just runs with no lights at all (green light off).

The exciter winding is what charges up the CDI. I have never seen one fail, except when an errant bolt got loose and smashed all the windings. If its making some voltage, that indicates that its not broken.You could try and get an Ohm reading on it, but that won't be super useful since we don't know what the value should be. However, if its some strange number (like in the mega ohm range) then that would show something wrong there.

paulz
Member
# Posted: 14 Dec 2021 12:15
Reply 


Quoting: travellerw
I have fixed a quite a few Hondas.. Those items are completely independent of the spark system. The inverter and overload protection will only disable the AC when somethings goes wrong


Yeah that's what it appears from the diagram. I'm going to go ahead and get that Honda replacement CDI. If it doesn't work I'll send it to you for your next repair, and for helping me out.

travellerw
Member
# Posted: 14 Dec 2021 15:47
Reply 


Ok.. One more thought before you buy any parts..

"Off-Brand" units often have wiring problems. Before doing anything else. I would plug all the connectors in a then back-prob (stick the multimeter prob up the backside of the connection). Back-prob both sides of the connector to ensure there is continuity through it. Check all other wiring to make sure its tight and has no breaks anywhere.

I have "fixed" many units that was just a bad connector. They often work for a while (even years) until finally the vibration breaks the connection.

gcrank1
Member
# Posted: 14 Dec 2021 16:02
Reply 


Yeah That!
I have a small brass safety pin on my multimeter wires as well as the 'gator clips that slip on the probes. I can clip an exposed terminal and pin-probe the wire anywhere to check. Several times Ive had bad con's in a block.

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