I'm considering the DSO shell (or DSO 138) for repairing some electronic music equipment and hope it will work well for that task.
I have some beginner questions:
1) What kind of use is the DSL Shell (and DSO 138) suitable for, and in which situations would I need a more expensive "pro" oscilloscope instead?
2) Why is there no way to put a 9V battery inside the case? This seems like a shortcoming in the design for becoming a fully portable oscilloscope. Connecting a battery externally with a wire hanging outside doesn't seem like a good idea.
I did however see a Youtube video review where there was mention of an internal power connector. Is this meant for an internal rechargeable battery? If so, what kind of battery should be installed, and will it charge by simply plugging power into the 2.1mm power jack connector?
3) Where can I buy a genuine DSO 150 Shell for a good price?
Is "Sseariver" on eBay a place to buy a genuine one?
Banggood was also mentioned in another thread. Is it still a place to get a genuine DSO Shell?
Beginner -should I get a DSO shell?
Re: Beginner -should I get a DSO shell?
1) The DSO Shell or DSO 138 are both suitable for audio frequencies (I have built both). At their price point, however, do not expect them to be precision instruments. The time-base is pretty good so frequency measurements seem to be accurate, but the voltage measurement is not precise. There is also some noise on the presented waveform, regardless of sensitivity setting. If you are just looking for the presence/absence of a signal as well as its general shape, frequency and magnitude, then either model is more than adequate. If you want precise voltage measurements, you would need a more expensive "pro" scope.
2) Not being the developer, I have no answer for why there is no space for a battery, other than - based on the stated supply current of 150mA - a typical 9V battery would only last about 4 hours, maybe. There is no charging circuitry provided, so you cannot use an internal rechargeable battery and charge it from the external power connector, unless you rigged up your own charging circuit. If you want an o'scope with an internal battery and charger, consider the DSO Coral.
3) I got both my DSO Shell and DSO 138 from Banggood; the DSO Shell just in the past month. Both are genuine. I don't know about the ebay seller.
Cheers
2) Not being the developer, I have no answer for why there is no space for a battery, other than - based on the stated supply current of 150mA - a typical 9V battery would only last about 4 hours, maybe. There is no charging circuitry provided, so you cannot use an internal rechargeable battery and charge it from the external power connector, unless you rigged up your own charging circuit. If you want an o'scope with an internal battery and charger, consider the DSO Coral.
3) I got both my DSO Shell and DSO 138 from Banggood; the DSO Shell just in the past month. Both are genuine. I don't know about the ebay seller.
Cheers
Re: Beginner -should I get a DSO shell?
cdw2000, thanks for your reply!
I'm not sure I understand some of the things you talk about (hence, a beginner with oscilloscopes
) but for measuring voltage I have a nice digital multimeter. I suppose you mean a good scope can be used for more precise voltage measurements beyond that, but that's outside of my needs.
But if I understand you correctly either scope will work fine for my particular use (to trace a signal in a non-working synthesizer and see where it stops/changes so I can identify the malfunctioning component).
You say either the DSO shell or DSO 138 would work for my use -since the DSO 138 is cheaper, what would the drawbacks be compared to buying the DSO Shell?
It's a pity about the missing battery, but I wasn't aware that a 9V battery wouldn't last that long with it. Still, I was hoping there would be a modification available for using a rechargeable battery. How about the DSO 138: does it have a battery option of some sort? What do you suggest the most convenient power source be for these scopes?
The DSO Coral does indeed seem nice with a battery and all, but with import duties and all it'll end up a bit on the costly side for me, so I'm leaning towards the DSO Shell or 138.
Thanks for confirming that Banggood are OK. Their prices are also very competitive, so I think I'll order from them instead of eBay. I didn't find them having the DSO Coral though, so I couldn't compare its price with those of eBay.
I'm not sure I understand some of the things you talk about (hence, a beginner with oscilloscopes
) but for measuring voltage I have a nice digital multimeter. I suppose you mean a good scope can be used for more precise voltage measurements beyond that, but that's outside of my needs.But if I understand you correctly either scope will work fine for my particular use (to trace a signal in a non-working synthesizer and see where it stops/changes so I can identify the malfunctioning component).
You say either the DSO shell or DSO 138 would work for my use -since the DSO 138 is cheaper, what would the drawbacks be compared to buying the DSO Shell?
It's a pity about the missing battery, but I wasn't aware that a 9V battery wouldn't last that long with it. Still, I was hoping there would be a modification available for using a rechargeable battery. How about the DSO 138: does it have a battery option of some sort? What do you suggest the most convenient power source be for these scopes?
The DSO Coral does indeed seem nice with a battery and all, but with import duties and all it'll end up a bit on the costly side for me, so I'm leaning towards the DSO Shell or 138.
Thanks for confirming that Banggood are OK. Their prices are also very competitive, so I think I'll order from them instead of eBay. I didn't find them having the DSO Coral though, so I couldn't compare its price with those of eBay.
Re: Beginner -should I get a DSO shell?
For a non-DC signal, your multimeter can only measure the RMS (root-mean-square) voltage. For a pure sinewave centered at 0 volts, the RMS voltage is about 7/10 (more precisely the square root of two) of the peak voltage (1/2 of the peak-to-peak voltage). See figure:
See this page for a more comprehensive discussion of RMS: https://en.wikipedia.org/wiki/Root_mean_square
If the waveform is anything other than a sinewave centered around 0 volts, most meters won't give you a correct measurement, unless you have a more expensive "True RMS" meter. Even a true RMS voltmeter can't give you a good picture of the waveform you are measuring. Suppose your circuit produces a triangle wave that is 3V peak-to-peak, but it is also DC offset by 5V. That means the waveform is centered at +5V and transitions between +6.5V and +3.5V. All your meter will give you is a voltage measurement of about 5V. It doesn't tell you anything about the amplitude (peak-to-peak voltage) of the waveform. That's where a good o'scope comes in. Both the DSO 138 and the DSO Shell can not only give you a picture of the waveform, but also have functions that allow you to measure the waveform, like peak-to-peak voltage. Max voltage, min voltage, etc.
Between the two, I would recommend the DSO Shell. It has a little more sensitivity range than the DSO 138, and a slicker interface with pushbuttons and rotary encoder, rather than mechanical slide switches. Plus its more compact and has a nice case.
See this page for a more comprehensive discussion of RMS: https://en.wikipedia.org/wiki/Root_mean_square
If the waveform is anything other than a sinewave centered around 0 volts, most meters won't give you a correct measurement, unless you have a more expensive "True RMS" meter. Even a true RMS voltmeter can't give you a good picture of the waveform you are measuring. Suppose your circuit produces a triangle wave that is 3V peak-to-peak, but it is also DC offset by 5V. That means the waveform is centered at +5V and transitions between +6.5V and +3.5V. All your meter will give you is a voltage measurement of about 5V. It doesn't tell you anything about the amplitude (peak-to-peak voltage) of the waveform. That's where a good o'scope comes in. Both the DSO 138 and the DSO Shell can not only give you a picture of the waveform, but also have functions that allow you to measure the waveform, like peak-to-peak voltage. Max voltage, min voltage, etc.
Between the two, I would recommend the DSO Shell. It has a little more sensitivity range than the DSO 138, and a slicker interface with pushbuttons and rotary encoder, rather than mechanical slide switches. Plus its more compact and has a nice case.
Re: Beginner -should I get a DSO shell?
Thanks for explaining!
One final question/observation: if I'm not mistaken it appears that the DSO-138 can indeed be supplied with an internal rechargeable battery!
According to JYE's website you can buy their (JYE-140 DC to DC converter PCB) along with their JYE-118 battery charger PCB which will charge a 3.7V Li-Ion battery, and it seems you can fit it all inside the DSO-138 acrylic casing to have it being charge with a standard USB power adapter, but I'm not 100% certain of this. Do you know if this is the case?
There's no mention of this possibility for the DSO Shell, but according to these Banggood user reviews a couple of people talk about using this setup with a DSO Shell as well. I just want to be certain that it indeed all will fit inside the enclosure and work without any issues. Which 3.7V Li-Ion battery is to be used with it? I'm sure that like with cellphone batteries there are a million sizes and dimensions to choose from (and also some that are safer to use than others). Exploding batteries don't appeal much even if I can save myself $ 0.50 for one without a protective circuit
One final question/observation: if I'm not mistaken it appears that the DSO-138 can indeed be supplied with an internal rechargeable battery!
According to JYE's website you can buy their (JYE-140 DC to DC converter PCB) along with their JYE-118 battery charger PCB which will charge a 3.7V Li-Ion battery, and it seems you can fit it all inside the DSO-138 acrylic casing to have it being charge with a standard USB power adapter, but I'm not 100% certain of this. Do you know if this is the case?
There's no mention of this possibility for the DSO Shell, but according to these Banggood user reviews a couple of people talk about using this setup with a DSO Shell as well. I just want to be certain that it indeed all will fit inside the enclosure and work without any issues. Which 3.7V Li-Ion battery is to be used with it? I'm sure that like with cellphone batteries there are a million sizes and dimensions to choose from (and also some that are safer to use than others). Exploding batteries don't appeal much even if I can save myself $ 0.50 for one without a protective circuit
Re: Beginner -should I get a DSO shell?
I'm just another user that happens to own both the DSO 138 and DSO shell. I have not attempted to retrofit either unit with a rechargeable battery, so I don't know easily a battery can be fit into the cases. Did anybody on the Banggood user reviews provide a picture?
Re: Beginner -should I get a DSO shell?
Yes, there's a photo there, but not anything that shows how it's done inside (go to the Banggood DSO Shell user reviews, and you'll find someone talking about how he used an old Nokia cellphone battery to get it working). Maybe he meant that although the battery was placed inside the DSO Shell, the DC-DC converter and battery charger w/switch circuit was placed outside of the unit. I prefer "idiot proof" solutions, so not exactly what I had in mind.
I went ahead and ordered a DSO Shell kit (pre-soldered SMD) earlier today from Banggood. I figured that if/until I figure out the battery thing I can always use a 9V power-adapter.
Do you know if there's a power regulator inside the DSO Shell circuitry, or is it critical that I get a high quality power-adapter with built in regulator circuitry so that it definitely won't exceed 9V no matter what?
I went ahead and ordered a DSO Shell kit (pre-soldered SMD) earlier today from Banggood. I figured that if/until I figure out the battery thing I can always use a 9V power-adapter.
Do you know if there's a power regulator inside the DSO Shell circuitry, or is it critical that I get a high quality power-adapter with built in regulator circuitry so that it definitely won't exceed 9V no matter what?
Re: Beginner -should I get a DSO shell?
Its best if you get a good, well-regulated power supply.
Re: Beginner -should I get a DSO shell?
I'll see what I can find though it's hard to know what's inside most "wall wart" power adapters. Perhaps the ones labelled "switched" are best. I'm guessing they have built-in voltage regulators and better filtering than the normal, cheaper ones.
I found the DSO-150 schematic and see that although there's a warning there ("Important: do not use voltage greater than 10V!") I see a LM1117-3.3V voltage regulator and according to its specifications it accepts an input voltage from 2.6V to 15V, so why the 10V limit warning?
I found the DSO-150 schematic and see that although there's a warning there ("Important: do not use voltage greater than 10V!") I see a LM1117-3.3V voltage regulator and according to its specifications it accepts an input voltage from 2.6V to 15V, so why the 10V limit warning?
Re: Beginner -should I get a DSO shell?
The ICL7660 negative voltage converter device on the analog board has an absolute maximum voltage limit of 10.5V and a spec'd limit of 10V.
I kind of wish they had used the LT1054, which is a better part, works up to 15V, runs at a higher frequency (25KHz), and with a couple resistors added can provide a regulated output. The ICL7660 runs at 10KHz and its output voltage is unregulated and load dependent.
Regarding the switch frequency - typically you don't want any power supply switching frequencies to be in the same area as the frequencies you are trying to measure (for noise immunity). At least at 25KHz, the LT1054 is outside the audio frequencies.
The LT1054 is pin compatible with the ICL7660, so I was actually thinking of upgrading my DSO Shell with the LT1054. I don't know if it will have any visible effect. The other improvement I was considering is to replace capacitors C12 and C13 with low ESR polymer aluminum types. This is supposed to improve the performance of the negative voltage converter by reducing ripple on the output voltage.
I kind of wish they had used the LT1054, which is a better part, works up to 15V, runs at a higher frequency (25KHz), and with a couple resistors added can provide a regulated output. The ICL7660 runs at 10KHz and its output voltage is unregulated and load dependent.
Regarding the switch frequency - typically you don't want any power supply switching frequencies to be in the same area as the frequencies you are trying to measure (for noise immunity). At least at 25KHz, the LT1054 is outside the audio frequencies.
The LT1054 is pin compatible with the ICL7660, so I was actually thinking of upgrading my DSO Shell with the LT1054. I don't know if it will have any visible effect. The other improvement I was considering is to replace capacitors C12 and C13 with low ESR polymer aluminum types. This is supposed to improve the performance of the negative voltage converter by reducing ripple on the output voltage.