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LCS-1M - A Full-Featured, Low-Cost Hobby Oscilloscope

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This instructable will show you how I developed a simple yet full-featured digital sampling oscilloscope that I hope will enable you to get a successful start in this domain. The main goals in this development were:

Create something that is really usable in practice - i.e. it must have sufficient sample rate to at least cover the audio range (DC up to well over 20 kHz), and a wide input range (from Millivolts up to several Volts). The present design actually is usable up to about 150 kHz (sample rate is 1 MHz = 1 million samples per second). The maximum voltage range is -15 to +20 Volts, but can also go down into the low mV range.

Use only readily available, inexpensive parts which don't need special skills to assemble - e.g. no tiny surface mount components. The whole scope can be put together with a cheap soldering iron, a small wire cutter and flat-nosed pliers.

Keep down cost as much as possible and design it in a way that all the components are easy to procure and assemble, so any moderately skilled hobbyist can build his/her own (see circuit description later).

Make it easy to use so even a user without much experience with oscilloscope gets a quick start, and make it compact so it doesn't use much desk space.

Last but not least, make it an open design so anyone can improve upon it. Note that the design may be used without any restrictions for personal, non-commercial use only. Any other use is strictly prohibited without explicit, written permission by the author.

You can get additional information as well as download the original design files (schematic, layout) and scope software from my oscilloscope homepage. From this site you can also obtain the bare printed circuit board and (as long as I have some left) the fully assembled scope and accessories.

In case you wonder what LCS-1M stands for, it's Low Cost Scope, 1 Megasample/sec.

Good luck!

Disclaimer (yes, this is a litigious world :-):

The author of these pages does not assume any responsibility whatsoever regarding the design, construction or use of the described circuit. The author cannot be held responsible for any damage to persons or property connected with the described design. This includes (but is not limited to) damage to your computer, fitness for a specific task, and specified performance. If you decide to build the oscilloscope and use it, you do so at your own risk. Observe safety guidelines when soldering, as well as when using the oscilloscope. Never apply any voltage exceeding 20V to the oscilloscope inputs.
 
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melwinalm6 months ago

Sir can you give me the program of the pic sir ? and the VB6 code for the pc software We need it sir this is my email melwinalm@gmail.com

womai (author)  melwinalm6 months ago

Firmware (source code) and PC software (executable only) are freely available for download on the scope website.

cyrohn1511 months ago
yes sir ..can you give me the program of the pic sir ? and the VB6 code for the pc software ..we need it sir ..we decided to make the project and pass it on our teacher but we need the code sir ..this is my email cyrohn15@hotmail.com ..
womai (author)  cyrohn1511 months ago
replied directly to your email
cyrohn1511 months ago
thank you sir ..we are from Philippines sir ..when we can have the kit if we buy this month?
womai (author)  cyrohn1511 months ago
I assume your question refers to the DPScope SE? (I stopped selling the Picaxe based LCS-1M kit a long time ago). In my experience shipping to Asia takes anywhere between 1-4 weeks, usually on the long side during peak times like Christmas.
cyrohn1511 months ago
Good day sir! can i ask a question in how to make the pc software ..
womai (author)  cyrohn1511 months ago
If you want to use the scope as-is, you can simply download the software from the scope website.

The software is written in Visual Basic 6 (VB6), which unfortunately is no longer supported by Microsoft (you can't even buy a new license anymore). For new developments I would recommend C# or VB.NET instead.
cyrohn15 womai11 months ago
thank you sir .. we love to built this project ,,sir we would like to copy the program in the pic ..pls send us the program of the micro-controller ..if we buy the kit ..how much we will pay?
womai (author)  cyrohn1511 months ago
You can download the firmware directly from my website:
http://www.pdamusician.com/lcscope/design_firmware.html

Same goes for the PC software, schematic, layout files etc.

I no longer sell the printed circuit boards though, so you either need to make your own (as said, the original layout is freely available for download) or build it up e.g. on a prototype board.
womai (author)  womai11 months ago
The design files (schematic, layout, bill of materials) is here:
http://www.pdamusician.com/lcscope/design_design_files.html

PC software is here:
http://www.pdamusician.com/lcscope/design_pc_software.html
womai (author)  womai11 months ago
If you want to build a kit supplied with all parts, I have a newer design, the DPScope SE, here:
http://www.pdamusician.com/dpscope/overview_se.html

This is much easier and cheaper to build since it uses only very few components.
ajoyraman2 years ago
Your Low-Cost Oscilloscope & DP Scope have been an inspiration to me.

Thanks also for the clarification you provided on sampling oscilloscopes.

I would love to get your comments on my recent instructable

http://www.instructables.com/id/Universal-Analog-Hardware-Testbench/

A non real time DSO is provided by the 'Capture Mode'

Where is the schematic, without the schematic you ain't going nowhere?
womai (author)  elfarandulero2 years ago
Steps 5 - 11 contain the full schematic (plus description of the functionality). Or you can download it from the oscilloscope webpage at http://www.pdamusician.com/lcscope --> Design --> Design Files
rashmi19903 years ago
Hi this design is bit complicated for a beginner

if some body want a easy design then check this link
http://microembeded.blogspot.com/2011/07/two-channel-pcbased-oscilloscope-usb.html
Eonir4 years ago
I have a noob question.

It is mentioned in the instructable that a USB cable can be used to connect the PC with the device. What kind of USB cable is it?
Is it perhaps this one?
http://www.sparkfun.com/commerce/product_info.php?products_id=8312

Can I use a cheaper USB<->RS232 converter instead? To connect it to the audio-jack only a few wires are needed.
womai (author)  Eonir4 years ago
Pretty any USB-to-RS232 converter cable should work. You can find them for just a couple bucks on Ebay.

Of course you may need to hack the RS-232 connector and attach a 3-terminal phono connector instead, or alternatively replace the scope's phono jack with a DP-9 jack.
Blackice5045 years ago
Hi there i am thinking of building this as i need such a device i can get a $165 real scope but it only has 20mhz bandwidth but it can handle 300volts on the probes. Say i not need to know the voltage and just see the waveform can i use a transformer on this scope to step the voltage down provided that i use a high freq type transformer and also what is the total cost to build this scope assuming i have all the tools? Thank you so much for this instructable i think its great that someone try's to save us money especialy when scopes are such a needed device but so much money.
womai (author)  Blackice5045 years ago
It comes down to what you need. In some respects the scope you sent the link to is more powerful than my design, and in some it lacks. Most of all, note that it only has one channel (mine has two), so you can't display one signal in relation to another (e.g. clock + data), which is quite a limitation. It does have better bandwidth than my design - 10 MHz vs. 400 kHz (or 1 MHz after upgrade). It has traditional knobs (some people prefer that), but my design makes it easy to e.g. take screenshots, save waveforms in ASCII format to process them in Excel, make numeric measurements with cursors, etc. If you need to extend the voltage range, the most straightforward way is to use a 1:10 or 1:20 scope probe (note that you'll need to make some small changes to the frontend of my scope to be able to use such a probe, because it needs a 1 MOhm scope input; the details are on my webpage and I'll be happy to answer any further questions). With such a probe the input range goes up to +200V and down to -120V (1:10 probe) or +400V / -240V (1:20 probe). So if you need the bandwidth, I'd look for a decent used two-channel cathode ray scope on Ebay - for $170 you should be able to get something useful. If you can live with lower bandwidth and want a more modern design (or like to build things yourself), go for my scope. Building my scope should come to well under $100, less if you can live without the enclosure; most chips it uses you can get a free samples (btw, that includes the Cypress SRAMs). If you did electronics before you probably have quite a few other components (resistors, chip sockets etc.) already lying around, which would reduce expenses even further.
Thank you so much for a speedy responce i mostly work with high voltage above 60volts. and you right high voltage is really dangerous even 9volts ac can give you a tingle or two but apart from that after reading that you said its probley best for me to have your scope for testings chips and things and use the bench scope for testing the high voltage it would be a scary thing to see 300volts run down a usb cable then stright into a 3.3 volt south bridge. thank you so much i will build this but later for now i need to play with high voltage as i am building invertor circuits.
womai (author)  Blackice5045 years ago
Regarding measuring high voltages, a transformer is not necessary (in addition it would have a lower-frequency cutoff so it won't display any DC offset). All you need is an ohmic divider. Apart from using a 1:10 or 1:20 probe you can also modify the resistive input divider of my scope. Right now its division ratio is 1:4 (100 kOhm and 33 kOhm), so if you make this 1:40 (e.g. use 390 kOhm and 10 kOhm) that achieves the same 1:10 scaling. That said, as also outlined in the disclaimer, I explicitly assume NO RESPONSIBILITY if something happens at such high voltages (e.g. damage to your computer or yourself); anything exceeding 20 - 30V is potentially dangerous or even lethal. You need to know what you are doing and take proper precautions.
Blackice5045 years ago
http://www.jaycar.com.au/productView.asp?ID=QC1920&CATID=12&form=CAT&SUBCATID=628

here is a link to the scope and its a type that is 10mhz as its 20Mhz
jam BD5 years ago
Sooooooooooooooooooooooooooooooo....
professional =D It's really good =D
This has got to be the biggest instructable ever!
learner12345 years ago
Hello. I am still trying to get the scope to work. The stage I am at now is the computer won't recognize the scope thru the serial port. On two different computers, after loading the programming editor and setting options as 28X2 and COM1, I get a "Hardware not found on COM1" message. I have meticulously traced continuity from the serial end of the cable to the pins on J_SERIAL. I have checked for 5 volts on the power in pin on just about all the ICs. The voltage regulators put out 5.07 volts. There are 1.67 volts between the serial in ( R) pin on J_SERIAL and groung (G) when the serial cable is connected to a computer. The only bad thing that happened was briefly I used a walwart with too high a current rating. The voltage regulator next to JP7 got extremely hot. Now, using a 300mA 9 volt supply , that regulator - screwed to the board- gets pretty darn warm- too hot to touch the screw after several minutes. I don't know what heat tolerance these devices are, but this seems too hot. I'm at a loss about what to do next. Could I have fried the PICAXE microcontroller or another IC when the regulator got too much current? Should I replace the regulator? Is this the stage where I have to sequentially replace ICs? Though I did change the line pwmout FAST_CLK_PWM_CHAN off to add a comma before the word off, and that seemed to correct a syntax error, I'm afraid my diagnostic skills stop there. I'm guessing that IC function could be checked with a logic probe, but have no knowledge of that. I'm not sure what pwmout is, but I checked the syntax in the PICAXE manual. Any help anyone can offer would be appreciated. Attached is the firmware file I modified
learner12345 years ago
It appears I fixed the syntax error in line 394 by adding a comma before the word "off". The Programming editor seemed to accept the revision and loaded something to the microcontroller. Now, when I insert the power cable, I get three flashes of the LED, then the LED stays on. However, the PC software keeps giving me an error " Could not find an instrument attached to the computer..." I've tried both the new software and the beta software without success. BTW, I switched the JP7 pins to TX. DO you have any suggestions? Thanks
learner12345 years ago
I have built the scope, using the Ver 1.1 PCB. While trying to download the firmware using Picaxe Programming editor, I consistently get an error code for line 364, pwmout FAST_CLK_PWM_CHAN off, saying "Syntax error". Do you have any insight into this problem? I tried using the Ver 1.3 BAS file, even though I know it is the wrong version, and got the same error.
davidkr5 years ago
Can anybody tell me how exactly to install the voltage regulator? It seems like some voltage regulators need to be bonded to a heat sink via a thermal adhesive. For this project, the voltage regulator appears to be attached directly to the board. Do I still need to use a thermal adhesive? Any advice would be greatly appreciated.
womai (author)  davidkr5 years ago
Thermal adhesive or thermal paste improves thermal conductivity to the heatsink. That's only necessary when running the regulator at higher power; for a linear regulator the dissipated power is the supply current times the difference between input and output voltage. I run the scope with a 9V supply and the regulators get warm, but not hot, and the regulators aren't even attached to the board at all. I have people telling me that one of the regulators gets hot if supplied with 12V or higher, in this case simply screw it firmly onto the board - the bottom ground plane will act as heat sink. I don't think at these power levels (the scope only uses 170mA of current) you need anything fancier than that.
Here is another novice question about the power supply. I purchased a " 9 volt, 300 mA" wall wart- nice word- from a local surplus store. The panel mount power jack ( Jameco151777) has three pins. I was expecting 2 pins, V+ and ground. When I measured the voltage at the pins, I was surprised to find 14.4 volts and 7.8 volts Here are my questions. 1. The 14.4 volts is just under the 15 volt maximum, so it is safe to use, correct? Or, should I be worried that the wall adapter is apparently mis- labelled as 9 volts, and discard it and buy another one? 2. What is the purpose of the second, lower voltage, roughly half of the maximum? Do all power plugs have this setup? Is the half voltage pin dependable to use, though in this case it is not enough voltage, being less than 9 volts? Thanks
womai (author)  learner 1235 years ago
Chances are your 9V (nominal) supply is unregulated. Because it has some internal resistance (the transformer's secondary coil) its voltage will drop when you put a load onto its output. Without any load 14V output is very possible. These simple DC supplies are sized so at maximum load (300mA in your case) they will give approx. 9V, at lower loads the voltage will be higher. The 7805 regulator can take up to >25V so you are safe. The scope takes approx. 170mA so chances are the actual supply voltage will not be much more than 9V anyway. The third ("half voltage") pin is not connected to anything, but is free floating. Chances are you get fooled by capacitive coupling in combination with the high input impedance of your voltmeter. Connect a resistor (maybe 10 kOhm) between this pin and ground and the voltage should disappear.
Thank you. Should I solder the two resistors ( 180 and 22K ohms) into the IC socket (CONV1) to accomplish upgrade 1?
womai (author)  learner 1235 years ago
es, bridging the socket pins with the resistors is the most elegant way.
Thank You. I sure learned something. The DMM is not always right. Your right, the voltage disappeared.
davidkr womai5 years ago
Thanks. That helps.
learner 1235 years ago
I am assembling the scope, PCB ver 1.1 enclosure and have a couple novice questions. 1. Are the pins on the breakaway headers ( J_LED, J_SERIAL) meant to have hookup wire soldered to them or are there single female leads with crimp connections available for a cleaner assembly? I soldered leads to J_LED and they look functional, but are messy in appearance. Soldering hookup wire to the various panel mount adapters is the most difficult job in the project, to me at least. 2. Is the correct hookup order for the phono connector to J_SERIAL- a ( fattest part of phono plug) to Rx, b ( middle portion of plug) to Tx, and c (tip of plug) to G?? It is not clear to me from the schematic, so I found a PICAXE datafile online that gave this information 3. For upgrade 2, using the 750/249K resistors and 18/43pf capacitors, in parallel, I intend to wrap and solder the capacitor wire on the resistor wire keeping the capacitor and resistor as close as possible, then solder the resistor wire to the PCB. Is this correct procedure? I suppose I will have to do the soldering as quickly as possible to avoid burning the components?
womai (author)  learner 1235 years ago
1. both solutions will work; soldering wires directly is a bit faster and cheaper (no jumper headers to and jumper cables to buy).

2. please have a look at the ExpressPCB layout file for the pin assignment:

http://www.pdamusician.com/lcscope/design_design_files.html

3. the easiest solution is to solder the resistors onto the board, then stick the capacitor leads under the resistor leads and solder them to the resistor leads. The capacitors and resistors aren't terribly heat sensitive (unlike e.g. diodes or transistors), so the solder speed isn't that critical.
Thank You for your reply. In this sentence I am asking if I have the correct order on the MALE part of the phono plug- on the serial-phono cable. Is the correct hookup order for the phono connector to J_SERIAL- a ( fattest part of phono plug) to Rx, b ( middle portion of plug) to Tx, and c (tip of plug) to G?
I'm collecting all of the parts to make the version with the enclosure, and I'm not quite sure what to do. The enclosure doesn't have any openings in it, and there are no replacement parts that do have holes for the cables. Am I supposed to drill the openings into the enclosure or am I missing something obvious?
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