The DSO138 Mini, rather surprisingly, does not have a BNC connector, unlike the DSO138 and DSO150, see BNC connector ? Instead is has a two pin header!
Fortunately there are through-hole resistors in series with the supply rails so it’s a fairly easy mod to replace these with 78L05 and 79L05 linear voltage regulators. The supply to the Zener diode was transferred to the stabilized 5 V and bingo, the zero line became stable.
78L05 and 79L05 linear voltage regulators to replace R22 and R28? But the Zener is 3V
DSO150 reference supply stabilisation
Actually, 78L05 and 79L05 linear voltage regulators to replace R26 and R27, and AV+ then replaces the V+ to the R28
DSO150 analogue voltage stabilisation
Also from the comments:
I tried the mod described at the end of the second page (“…it’s a fairly easy mod to replace these with 78L05 and 79L05 linear voltage regulators. The supply to the Zener diode was transferred to the stabilized 5 V and bingo, the zero line became stable…“), and I have to say it didn’t work well for me at the beginning, because the zener diode didn’t reach 3 V. I think it was because it didn’t get enough current, as the resistor feeding it from unstabilized 8V is 1K, (approx 5 mA), so when you transfer it to 5V the zener would draw only 2mA. I changed the resistor to 330 ohm and after that the zener again reached 3V properly.
So this is R28 which is 1 kΩ and changed to 330 Ω
It should be noted that hardware versions E and F already come with the 7808/9 (see also Re: Li-ion power mod):
[ 2017.05.08 ]
Improved trigger algorithm and made trigger more stable and accurate. With the new algorithm, external trigger is not required. As result, the TL_PWM (PB8) and TRIG (PA8) pins and TIM3 were freed and can be used for other purposes.
Note on the combination charger booster used by Morgan Flint, from Re: Li-ion power mod:
Unless you you perform some delicate surgery on this module and wire your On-OFF switch between the charging circuit and the step-up converter (as described by MorganFlint on the 1st page of this thread) this module is a poor choice for this application. The reason is that this Charging/Step-Up module as is, draws almost 0.5mA from the battery in standby compare to only about 20uA if you separate the charging circuit from the step-up converter.
Also, by having a separate step-up converter, it allows you to select a better converter like the one I used which has an additional LC filter on its output with a very low switching noise which is a bit of a problem with the standard step-up converter.
Third: Charger+Booster module modification to avoid quiescent current to drain the battery when not in use. I had to unsolder C2, cut the tracks as shown and resolder C2 to the pads for battery connection:
The battery finally arrived, and I was able to complete the lipo mod.
As mentioned before, I have the old style boards, and the analog board extends about 6mm further into the lower part of the case than the newer board. So the BH6X battery just wouldn’t fit. I ended up using this battery:
It is 50mm long by 34mm wide by 6.6mm thick, and 1300 mah. There was almost enough room to lay the booster module next to it, and in the end I just let the module lie at an angle against the battery, which worked fine. I removed the pot from that module and replaced it with two 56K fixed resistors in parallel, or 28K net, and that gives me about 8.2V output, which is about right since it doesn’t go through the diode.
LupinIII wrote:…BUT, if you want to keep the barrel jack, I just saw something that I’d use. The socket got an unused contact that is closed when no connector is inserted and opens if you insert a plug. It breaks the ground connection (but that shouldn’t matter). You could solder the GND output of the boost converter to that contact, so if no external plug is inserted the boost converter is connected to the 9V input instead automatically…
That’s exactly what I did, see 3rd paragraph at this post and the one before the last picture at this one.
RobNL’s correction, from Re: Li-ion power mod, for the all-in-one charger/booster board
Why not like this ?
In off position you can charger the batterie without power concumption from the batterie.
In on postion you can use the 5Volt USB and the 9Volt barrel to feed the shell.
Release the USB in off position and there is no power at all to the shell.
Your booster is disconnect in off mode, you don’t need it in off mode.
The lipo is connect to the booster in on mode.
The lipo in connect to charger + protection in off mode, so in off mode you can load the batterie.
In on mode you can’t use the load + protection, you don’t need it.
If your batterie is empty, you can use the barrel.
BTW, the extra diode is sometimes allready on the boostermodule.
found this on thingiverse, a kind australian has provided this for diy 3D printing.
the beveled housing makes it easier to read as a tabletop device
there is enough space for two 18650 LiIon cells and charger equipment e.g.,
if you switch them to 7.4V in series not need a stepup converter and have a clean supply voltage
Whoever came up with this idea of using two Lithium batteries in series without a step up converter did NOT do his homework and take into account worst case condition of the batteries voltage. THIS SCOPE WILL NOT FUNCTION AT BATTERY VOLTAGE OF 6V!
Anything less than 7.5V is very unpredictable! Most Lithium battery charger/protection circuits will allow full battery operation down to about 3V per cell (that is how Lithium battery capacity is determined and circuits designed to operate) and with two of them in series you will get ONLY 6V which is in this case unacceptable!
…
It is unpredictable and it will vary from unit to unit. Basically at around 7.5V, which could actually be 7.5V ±0.5V the +5V and the -5V regulators will stop regulating and then anything is possible. The problem is that at that point the scope will NOT just die but will stop functioning properly and the results will be unpredictable.
You can raise a little this minimum input voltage by about 0.6V by shorting out the D2 diode next to the power input connector. Other than that, I would strongly suggest using just one Lithium battery and using a step up converter with an output of 8.0-8.5V (still short out D2, there is no need for it). You will be able to fit a larger battery and get much longer run time. Take a look at the bottom of the first page of this thread, you will see my implementation of this project. BTW, I am a EE so I know what I am talking about.
I’ve seen mentions here that the scope can be operated during charging, but I think doing that for extended periods may not be a good idea. The TP4056 charger is supposed to shut down when the charging current reaches 1/10 of the nominal max charging current as set by the R3 resistor selection. But if the scope is on, the current will never drop that low, and the charging voltage will remain at 4.2V even after the battery is fully charged, which is not good for the battery, and may be potentially dangerous. There’s an excellent video by Julian Liett on these charger modules, and at 11:07 he talks about this problem:
In Toshi’s zip file containing his software and hardware modifications for the DSO150, he has the battery supplying the boost converter through a schottky diode, and the 5V USB V+ also supplying the boost converter through another schottky. So when USB is plugged into the charger, the V+ 5v will be higher than 4.2V, the battery diode will be reverse biased, so only the USB V+ will be supplying the converter. That would allow charging to shut down normally. But I would rather avoid the voltage drops in the diodes, and just make it my practice to turn off the scope when USB is plugged in.
Source code 113-15001-060 was released in May, but bugs remained in the library.
It seems that it takes time to fix the bug at jyetech, so I will release the software modifications I have done so far on a temporary basis.
I hope you find something useful.
I will upload again when the bugfixed library is released.
Change point
(1) Addressed the problem that trigger level setting due to long press of TRIGGER does not function properly.(temporary solution for 113-15001-060 library bug)
(2) Addressed the problem that the left half of the measurement result display does not function properly.(temporary solution for 113-15001-060 library bug)
It is not possible to cope with the incorrect capture of the beginning of the sampling buffer and the case where offset is caused by a sweep of 50 ms or less because it is a bug inside the library.
(3) Increase the movement amount in proportion to the rotation speed of the encoder.
(4) Correspondence of missing encoder data reading.
(5) Numeric display of trigger voltage level.
(6) Serial output of waveform data.(Short press of the encoder knob)
(7) Key repeat after long press of the button is prohibited.
(8) Change of VSen and Timebase is prohibited during waveform hold.
(9) Other minor bug fixes.
In addition, I will introduce the modification of hardware.
(1) Internal installation of battery
(2) Noise reduction
For details, please refer to “DSO150 Modification of software and hardware.pdf” in the zip file.
I believe you don’t need to mod the switch.
jye1 already made a board that do all of the things you guys want.
It is here.
And if you don’t want to buy that you can even make yourself a switch from that schematic.
All you need is that transistor Q1, D2 and R3 from figure 1.
Top line is from USB, BATT line is from battery and VOUT is going to your switch on the main board of oscilloscope (SW5).
What it does is putting voltage from USB to Vout or voltage from BATT to Vout (if there is no USB voltage present).
If you have USB voltage present it is actually charging the battery and also providing power to oscilloscope.
I use it for quite some time now and it is working as expected.
…
My oscilloscope modifications:
– 1500mAh battery 504050 and it is like this – it fits without any modification
– charger for battery is here
– step up converter is here
– after I power oscilloscope I have this display to tell me the voltage of battery
– I also made some modification of the case so that I can upgrade firmware without opening the case
Data USB download
See JYE Tech DSO150, Data download to PC (requires firmware 113-15001-110 and Toshi)
The relatively small ADC input range makes it susceptible to interference from other fast signals such as horizontal sync pulses. In an effort to reduce their influence I added some additional bypass capacitors to the supply rails but this wasn’t very successful.
External trigger is available only with firmware version 113-13810-110, which will be posted to our website soon. The input for external trigger signal is PB15.
Even though the DS138 mini does not come with a BNC connector, there is still a place for it on the PCB. Compare the DSO138 which does come with a BNC connector
This BNC connector is from Renhotec Group (www.renhotec.com) and the part is “Renhotec-610-0029”.
It is sold by 2 pieces on AliExpress (BNC Female Jack Right Angle PCB Mount BNC Socket Chassis R Connector)
gr33nonline 
where can I get a replacement encoder switch for the oscilloscope ?
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Hi, I have created a ifixit guide for update to battery driven: https://www.ifixit.com/Guide/mini+oscilloscope+DSO+150+-+update+to+battery+driven/142254
I hope it is usefull.
Br Carsten
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Nice one! Well done 🙂
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