DIY oscilloscope probe for Android device ⚡️UPDATE⚡️
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- เผยแพร่เมื่อ 16 ธ.ค. 2017
- ⚡️See notes below⚡️
I needed a way to test a hall effect type speed sensor on a Mitsubishi Galant transmission. The test procedure required an oscilloscope, which I didn't have. After a bit of searching, I ran across a basically free method of making my own oscilloscope. See link below.
Inspired by: retronics.wordpress.com/2012/...
Voltage divider calculator:
learn.sparkfun.com/tutorials/...
The app I used was called Smart Scope, but there are a bunch of oscilloscope apps available on the Play store.
⚡️NOTE⚡️: as pointed out by James Smith down in the comments, I had the diagram labeled incorrectly. To achieve a tiny output voltage compared to the input voltage, resistor R2 needs to be the smaller of the two resistors.
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If this helped you out and you'd like to show your appreciation, donations are accepted :
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I have been trying to figure out how to do just this
and I had over complicated it, practically beyond
comprehension. Thanks to you, now I understand.
Not all heroes wear capes, and for today, you're my hero!
Thank you for the instructions.
Brilliant work. Very concise & informative video. Many thanks for posting. Cheers from Australia.
Thanks, clear presentation and useful!
Thanks to your info I now have a oscilloscope app on my smartphone that is picking up signals nicely using the DIY probe you showed. Ready to check the CKP sensor signal of my engine.
Congratulations on vid.
Thanks for the very clear video! I'll be cutting up an old pair of headphones when I get home.😀
what a relief to find your video! I've looked at several videos on how to make a scope to use on Android but this is by far the best plus you didn't use anything id have to go out and buy. i need to see the waveform of my 05 Acura TSX k line (high speed CAN line) bc im having a lack of communication from TAC module. actually what i really need is to check if the low and high speed CAN lines mirror each other but I'm gonna give this a shot and see if i can figure my car prob out with this before i go spending more$ on tools etc.. I've already replaced the TAC module but it's not working still!
Great little project......thanks! I am building a DSO138 but I am going to make this one too! Very clever!
Audio jack scope is inferior to DSO138 on that it can't display DC signal.
Because audio by nature are AC component so input inside female plug has DC block filter aka. capacitor.
Thanks. This is very helpful.
Nice info, thanks for sharing it :)
Thank you very much,very good video.
a good video finally thank you for the video
Very Cool!
Thanks for this awesome video .could you help me .i didn't know how to use voltage divideing i couldn't understand .what resistors should i use to measure the CKP and Cam shaft sensor .
very good video, thank you
thank you for vedio...very good
What your metode can be check for audio like power amp sir......thanks
Thanks for this video. Which Android app you are using for this oscilloscope tell me, please.
Hola dustin un saludo una pregunta tu osciloscopio es en un cecular 2 las resistencias de cuantos ohmios son gracias
very nice sir idea. ( possible reply me, what is code your reisitor at 2pcs? thabks
i have a LG phone (L90) and this use the WCD9320. The datasheet show that it support a max negative voltage of -0.3 and positive of 2.9 max. the app show a maximun voltage to +/-1v. what happen with the negative voltages?
I love it
Use high frequncy?
Your video likes & dislikes are also in 10:1 ration :D, keep the good work
wonderful video... can I use an android oscilloscope for probing all the signal in the car?.... or just only sensors that ranges between 0-5 volts???
with that probe ratio up to 5 V would be safe for smartphone
As noted in comments below, his circuit diagram has the two resistors reversed (wrong). He wants the resistor divider circuit to reduce the 5v max input voltage (on the left) down to 0.5 Vpeak on the microphone input connector (right of diagram) is designed for (I am guessing he knows or assumes the max = 1Vpp (+/- 1V) , which is a typical audio line voltage value (I do not know if this is true for his phone).
Voltage reduction formula for the ratio of Vin / Vout = R2/(R1+R2) = 15.8k/(1.5k+15.8k) = 0.91 if done as the diagram shows. This means the voltage is reduced from 100% to 91% of input with is not enough of a reduction.
If you swap them so R2 is the smaller one, Vin /Vout = 1.5k/(1.5k+15.8k) = 0.086 = 1/11.5 which is close to the 1:10 he wanted).
Note: TO get a more exact 1:10 reduction, use 1K and 9K or 1K and 90K Vin /Vout = 1.0k/(1.0k+9.0k) = 1/10 or any resistors when the bigger one is 9x the smaller one.
Shouldn't you add a capacitor on the input some high voltage might come thru and whack your audio input on the tablet
That’s me cutting up the wife's...I mean some old headphones. A great little project, thank you.
There seems to be an inconsistency between your diagram an the voltage calculator on that link. With your R1 & R2, the voltage would only drop from 5V to 4.57V (not 0.5V as you state). To drop 5V to 0.5V would require the resisters to be swapped, having R1 be the larger.
Huh...you're right. It's strange that a 5V signal was showing as ~0.5V on the scope though. Now I need to test a constant voltage through the adapter and just measure on the ring/sleeve of the headphone jack with a voltmeter. Maybe I had it drawn one way and soldered it up differently than I had it drawn.
Thanks for pointing this out. Since there's no way to change the video, I changed the title and added some notes to the description. Hopefully any future views, people will read the updates.
Right. I was writing a comment when I saw your comment - in order to protect de microphone input with a 1 to 10 voltage atenuator, the first resistor must be ten times the second one ( connected to ground).
And it's 1 to 11 if anyone cares.
@@DustinRogersinMO you probably ended up soldering the resistors "wrong," the two errors canceled and the result was the desired one.
Did u use oscilator circuit?
Thanks for this experiment , I have a question for my work, I am testing signals between 0 ~ 30 V what is the proper resistors values should i used ???? and it difference if the Volt is DC or AC ??
first try to know max voltage phone' s jack take in say 3v, 1mA
now you are about to read 0-30 volts
thats is for your jack 3v is 30 volt right, with zero or negligible input current,
so you can use voltage divider formula to calculate
or say it
100k and 22 k, and 100k will in series and 22 k will in parallel,
one more thing you can take resistance values in Mega ohm, as we are here to measure voltage waveform not current,
Hi - are those resistors ok to test a car components? Like EGR valve or temperature sensor? gr8 video btw :)
Marcin Wojciechowski yes. I used this to test a speed sensor on a transmission.
But you’ll need to find out what voltage those sensors use. The speed sensor that I tested put out 5v. The resistors that I used divided voltage by 10, so my tablet was only receiving ~0.5 volts. The headphone jack can only handle ~2volts so you’ll need to adjust your resistor sizes to divide the voltage to a safe level for what you’re testing.
Very interesting. I'll try to assemble it. I need to have an oscilloscope to see if I have a good signal coming out of my radio unit and to see when it starts clipping (squaring up the sinusoid). Will this device show me reliably the distortions? Thanks man
You might want to look at the DSO150 from Banggood for your requirements. They are only about $15 (free delivery) right now if you do the soldering (it's easy) or around $25 if you get one already made. They work great for the rf audio range and are very intuitive to use. DO NOT get one from Aliexpress or Ebay as they are mostly fakes and you HAVE to get a code from the maker before use (they email back overnight!) and they won't issue a code for fakes. Banggood only sends genuine units so you are safe there. Hope this helps. May be too late but might help someone anyway.
How to measure DC. It shows straight line at zero axis
Can you clear up some points for me?
Point 1: Is the max. input voltage rating of port in smartphones 3.0 V?
Point 2: Do I have to connect the microphone wires or the audio wires to the resistor network?
BTW, thanks. Your video seems to be the most comprehensible of all of the ones out there!
1: It probably can't take more voltage than that.
2: The microphone ones.
Which app did you install on the tablet to give the oscilloscope visualization? Thanks
Info in video description
I notice that for many of the Andriod phones, the 3.5 mm 4 Pole Audio jack, the pinout is different from your video. The last ring is for the Mic and the third ring is for the screen. In short the connection is reversed. Could you please clarify is this correct ?
I can confirm MIC and GND are reversed on the set i used
Very interesting. Can we use this setting to make our android phone as a function generator?
There's a REALLY good one i found that is totally free (and no ads!) just called Function Generator from keuwsoft might help you better...? Here: play.google.com/store/apps/details?id=com.keuwl.functiongenerator and no, i have no affiliation.
Now i have to biuld one cos my ocd is kicking in lol
The forumla is Vout = Vin * (R2 / (R2+R1)). Vout = 5 * (15800 / (15800+1500)). Vout = 4.566473988439306.
I followed the instructions in your video and everything seemed to work correctly when I checked the continuity with a multimeter on the wires from the ends of the leads to the rings on the headphone jack.
But I couldn't get any signal on the app itself. I tried several apps on two different android smart phones and none of them would show a signal inside the apps. I would be grateful for any advice or guidance you could give me to help me get this working. Thank you in advance.
Hi, you can use this preamplifier very easy to build and very cheap and safe for your device. I made one last weekend and it works/ here is the link with instructions, www.instructables.com/id/A-Preamplifier-for-Smartphone-Oscilloscopes/ I hope you find it usable.
@@josegilmeralvarezb.5309 Thank you very much for posting this. It is helpful but it's a little difficult for me to get these parts to build this, but I do see the value in it. I shot a short video and put it on my channel as to how far I got with trying to make this type of oscilloscope. If you're able to please watch it and if you could give me any feedback as to what I'm doing wrong I would be most grateful. Thank you very much for your comment and your help.
@@josegilmeralvarezb.5309 thanks for the link.
Nice video. Wonder what the sampling rate is...
Probably 22 kHz sampling... The normal audio sampling rate.
Splendid Video but I have some questions.
1) Did you use the multimeter to find which wire strand goes to which ring of the Earphone pin?
2) Which Application did you use to show the output?
Please reply as quickly as you can ^_^
Yes, you’ll need to do continuity tests to determine the correct wire to hook to.
The app I used was called Smart Scope but there are many available on the Play store.
Good job , please what is the max voltage can be used thx
NASRY Farid it probably varies by device but I wouldn't exceed 3 V
input voltage 220v AC R1=10 kohm, R2= 50 ohm i will get 1.095 as input voltage to phone
can i use this and test it with my phone!
Thanks in advance
NASRY Farid I didn't check your math, but you could always build the probe and hook it to your voltage source before plugging into your phone. Use a voltmeter to check voltage to be sure you are under 3v.
Thanks a lot you r the best
i will test it and i will give u the result My best regards
Would it be a good idea to add a potentiometer to measure high and low voltage?
Yes, that's definitely an option. I just didn't have one and needed this right away.
@@DustinRogersinMO thanks for the quick reply have a great day
Where i have apk on android?
android library source code?
Which app did you use. You didn't talk about the oscilloscope app that is in your video. The presentation is not conclusive
The app I used is in the video description. Also this video is 5 years old, so it’s hard telling if that app is still being supported or available.
Some Notes:
- The Impedance of the line in is typically around 10kOhm
- Vpp of the line in is 2V, so Vpp of this 1:11 Ratio Oscilloscope should be around Vpp~=22V
- The max Frequency should be around your phones line in sampling rate (usually only 48kHz), so it sould have a Frequency band of only 0 - aka. this oscilloscope isnt for high frequencies at all.
I havent done this project myself, but due to being a poor student I'll probably make one of these myself in the near future. I might add 2 1V Zener diodes in row(facing each other ->----->-->---LineIn[-] LineIn[-]--->-->-->---LineIn[+], so that the 0,7V Forward bias Voltage in each direction adds up to 2,1V)
or Ill just be lazy and do nothing about that ¯\_(ツ)_/¯
nice project though the resistors are misaligned
What is the app you are using on the tablet?
Mark Aulik check the description
Let's put 1 GOhms VS 1 Ohm to measure lightning voltage. Warranty void if measuring actual lightning.
What is the max voltage range?
Oblivion Tech, he said max voltage on an android device can take is right around 3v. If that is so, then two resistors in a 1 to 10 ratio, and 3 volts max on the small resistor means 30 volts max across the larger resistor, totaling 33v max voltage to be sensed on the probes. If your your ratio is 1 to 100 and you can drop up to 3v on the small, then your drop upto 300 on the larger resistor, totaling 303v max voltage to be sensed on the probes. Note: in his drawing, R1 should be R2, and R2 should be R1.
While he said 3v, i see other sources say 2v. It maybe that different android vendors have different specs.
Keith Reynolds - Spot on. I've seen max input claims in the android anywhere until 3.5v, some even claiming it could go as high as 4V.
So I would be comfortable to work at a max. of 2.5v, just in case.
Although totally willing to try it. I'm in no way willing to fry my phone. ;-)
What Oscilloscope did you use?
The name of the app I used is in the description
But this video is 5 years old, so not sure if that app is even still available
Good job men but you need camera men help when filming
can i gate that software application
It's called Smart Scope, but there are a bunch of oscilloscope apps available. Some are free, others you have to pay for.
you need to ground that pin black
1:10=r1-1.5 and r2 -15.8 but 1:100 ?
SANJAY KUMAR you’d just need to use a resistor for R2 that is 100x R1. So if R1 is 1.5k then R2 would need to be 150k
what is the application name
all info should be in the description
what app are you using?
capuchinho Pcb I believe it is called Smart Scope, but there are a lot of free oscilloscope apps on the play store.
aaah.. don't get into the spinning wheels or this project will go for a drastic change...:/ nice info...:)
I am surprise that he didn't even mention the most important part of this operation: THE APP he is using. I think he has experience in what he is saying, but staying silent about such an important aspect of this project, and also by not showing how his circuit connects to the car brings to question the integrity of his project.
Or you could read the video description where I specify what app I’m using 🤷🏻♂️
As far as how it hooked to the car, the two clips attach to the pins that need to be tested for whatever sensor you’re trying to test. Each sensor is going to have a different testing procedure and that was out of the scope of the video.
hindi mai speak karoge to very usefull
Tablets don't have a microphone jack! Only smartphones have them.
Don Cankook huh? I have a 7” and 10” tablet that both have headphone jacks