Use Your Laptop As Oscilloscope





Introduction: Use Your Laptop As Oscilloscope

Oscilloscope is an electronic test instrument that allows projection of voltage signals to be displayed and learned. A specific circuit in the oscilloscope creates repeated moving signals from left to right. This repetition creates non-repeating waveforms that can be learned.

Oscilloscopes are commonly used to observe the exact wave shape of an electrical signal. In addition to signal amplitude, oscilloscopes can show time distortion between two events (such as pulse width, period, or rise time) and relative timing of two related signals

Below is a picture of common Oscilloscope.

Today, Oscilloscope uses LCD color display, displaying better graphics

Step 1: Make Your Own Oscilloscope Using Your Laptop Computer

Once I need an oscilloscope to see the electrical voltage ripple in the car. Ignition systems, alternator rotation, high-beam lights flicker, and others are generally emit noise or voltage ripples, Well, this is what I want to know, size of the noises, etc.

Oscilloscopes are very expensive tools, and generally are only used in electronics / electrical laboratory.
Finally, I found an application that could use laptop computer / PC as Oscilloscope by adding some components as interface.
Those components are simple and quite cheap!

The necessary components:
• Two 22K ohm Resistors
• Two 82K ohm Resistors
• One 50K Linear Potentiometer + Tuning Knob
• One meter Shield Stereo cable
• One 3.5mm Stereo Jack
• Tester Terminal

Step 2: Electronic Scheme

• The 22K Resistor serves as voltage safety limit into laptop soundcard.
• The Potentiometer serves as input voltage resistor. If the voltage is above 5volt, adjust the potentiometer necessarily to prevent the soundcard from being damaged by excessive voltage input.
• Use shield audio cable to prevent induction around the cable.

Step 3: The Probes

Attach the probes

Step 4: Testing

The unit is ready,

Plug the Stereo Jack into LINE-IN/MIC

The application is ZELSCOPE, free download at .
This application is 14-day Trial, could be purchased at a price of not more than (US $9.95).

The Oscilloscope is ready for use!!
Below are several voltage signal tests, among others signals from mobile phone charger, laptop charger, battery, etc.
Sample of close-to-perfection voltage signal without noise.

1. This Oscilloscope could be used for a maximum input voltage of 5Volt.
2. This Oscilloscope has a frequency range of: 20Hz to 20 kHz (complying with the Soundcard capability).
3. The value of 22K Resistor could be increased up to 820K Ohm for the use of Oscilloscope with an input of above 5 volt.
4. The value of Potentiometer could be increased up to 100K Linear, for the use of Oscilloscope with an input of above 5 volt.
5. For safety of your Laptop, you can use cheap USB SoundCard (under $5).

Good luck.


Translated by Taufik Masjhur
This post was originally published on in Bahasa Indonesia language.

2 People Made This Project!


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55 Discussions

hallo an unbekannt, eine sehr gute idee mit dem scop für pc und laptop , werde es mal testen und berichten , werde versuchen ein selbstbau ekg über das scop wiederzugeben .
danke euch allen transistorkiller

I am looking for a circuit idea that can pick up the sound/music from the microphone/headphone outlet and can store the frequencies on a SD card , frequency can be sampled at every 10 to 20 milisec, I wonder if your present project idea can be useful ?

would this design be able to read around 1.5hz or would it need to be modified?


8 months ago

Nice to see someone added blocking diodes to protect the circuit and also protect the PC. I had a friend, retired nuclear physicist, a really knowledgeable guy. For some reason he used a couple of very expensive, very elaborate, oscilloscopes (one after the other) to see a trace of an auto ignition system and ruined the front end of both. Be careful and you can do a lot with this little circuit.

1 reply

Please give me scatch and detail of diods... i want use it for safety

I really like this. Good tool to get familiar with scopes. I want to use a defective cheap multimeter to house a cheap sound card (to test and avoid damage and it is USB) and all the components you mention here. The selection knob can be the fine-tuning knob and you can use the standard available probe connections. You can also remove the faceplate (because it is a sticker) and print your own faceplate for it. Sounds pretty cool right? I will post it here when my approach is successful. Thanks for sharing this.


1 year ago

can i use this circuit for a smartphone .. i know that there is another methode for phones but i like this one .. does this work for pc and smartphone ?

Another software Oscilloscope

There are several versions of this free software oscilloscope program. Google it. It can also use the PC microphone input as a signal source.

ScreenHunter_110 Mar. 23 15.58.jpg

ps. I did use a pair of zeners between the rails.

You say in the Instructable: "

The application is ZELSCOPE, free download at .
This application is 14-day Trial, could be purchased at a price of not more than (US $9.95)." But , in the comments you said, "

The software you can use is: ." This one (Soundcard Oscilloscope) you use in the "PC SOUND-CARD SCOPE INTERFACE FACILITATES DC RESTORATION" Instructable. Can the Soundcard Oscilloscope be used for BOTH projects? Also, I want to measure the frequencies of a Tesla Coil and other HV/HF devices. Can I use, for example, a transformer and current-limiting resistors between the Tesla Coil and the O-scope leads to protect my computer?



1 year ago

I need oscilloscope to show output wave 220 volt Ac.what should i do?
Thank you

Hi, I want to use my laptop as both oscilloscope and signal generator. In such case, how can I separate the signal of the signal generator (output), from the signals to the oscilloscope (input)? Do you have any circuit diagram that does this?

Great minimum component interface ! For safety/protection I suggest you add a couple of back-to-back 2 X signal diodes across the 82K resistors which would restrict the sound card input voltage to approx 1.4 V.


4 replies

you have 2 of the diodes not in their correct polarity, back to back diodes will work as long as ratings are not exceeded, however this diagram will cause a short and could damage an already very poor person's personal computer!! This is totally unacceptable. Back to back diodes is usually implying one forward biased diode in series with one (respectively) reverse-biased diode(usually identical diode model).

Yes, the terminology 'back-to-back' is incorrect. What I have suggested is two diode-pair clamps with opposite polarities. When the input voltage exceeds ~ 1.4 V of either polarity it is clamped by the diode-pair and the rest of the voltage is across the input series resistance. This resistance also acts as a current limit.

is it fully safe now? if I add the 4 resistors? i am trying to build 1. And what software can I use for this?

It is quite safe as long as you remember that the ground of the PC is not isolated and so we should avoid measuring the AC mains or other circuits not isolated from the AC mains.

The software you can use is:

This instructable uses passive components and the impedance of the sound-card may attenuate the voltage inputs.

You can also see my instructable which uses active components:

Hi, all looks very good, but changes would I need to make to have to measure up to 250V with current up to 20A? Just have thicker wires? Thanks

1 reply

i guess u can put a stepdown transformer, a resistor and a capacitor into thr circuit.

The transformer will lower the voltage.

For the capacitor, make sure that the inductive reactance of thr transformer is equal to the capacitive reactance so that the added RLC circuit wont affect much the waveform produced by the ac generator ur working in. And the resistor will lower the current.

This is just my theory.. i hope it helps..