Beginners, Scopes and Mains - Page 1
Forum section: electronics / beginners

author: fsenseman
author_rank: Newbie
timestamp: September 24, 2020, 02:06:57 am
content: I've seen some references on here to the proclivity of those who have just received their very first scope to plug the damned thing into the mains. Indeed, I just got mine, based on some great info here in the forums. I'm afraid the scope I bought had nothing to do with gender but rather a teardown on a certain PC based scope. I digress...Well, being a rank beginner I got my scope and figured out how to do a square wave with the built in reference signal. That was pretty cool but after a very short time the novelty wore off. A sine wave, that was what I wanted to see. Ok, where's the most accessible sign wave for a noob. Oh yeah, the mains!I refrained from frying myself and said there had to be a better way. There was. I bought a function generator kit and soldered it up. It was an XR2206 based kit, about $8.00. Built it, hooked it up to my scope expecting to see a nice sine wave and nothing. I don't know if was a bad XR2206 or a botched assembly. Or my scope skills. Undaunted I purchased another kit with a different chip. It was an icl8038 which gave me two of them for the same price. Put it together and voila!! Nice sine wave, saw wave and square wave. I was happy.Now, to the real point of my post. I still didn't know how to use a scope. I stumbled across a PDF available from the University of Washington that gave some very basic instruction. The link is:http://courses.washington.edu/phys431/scope_ex/scope_ex.pdfI am now cured of the desire to stick my probes into the mains and I know a bit more about how to work my scope. Well worth checking out, in my opinion. I hope this helps somebody because I'm gonna need help soon, I'm sure!

author: Shock
author_rank: Super Contributor
timestamp: September 24, 2020, 06:39:36 am
content: Welcome and congrats, yes that is exactly the best way to go about it there is a lot of material out there in the way of guides including those mentioned here. Even user manuals for any oscilloscope can be enlightening if you use them to understand the functions oscilloscopes can perform.With regard to sexual identity and gender, unless I'm mistaken this isn't an online dating site. Due to electronics being a solo and male dominated hobby/profession being catfished from a bored/lonely guy is statistically more probable than finding true love.Anyway now for homework you should attempt to troubleshoot your first function generator kit.

author: BravoV
author_rank: Super Contributor
timestamp: September 24, 2020, 06:49:00 am
content: Quote from: fsenseman on September 24, 2020, 02:06:57 amNot sure if this will cure or fulfill your desire if its still there, prolly just mild treatment I guess, then head over ->HERE

author: fsenseman
author_rank: Newbie
timestamp: September 24, 2020, 09:44:01 am
content: Quote from: Shock on September 24, 2020, 06:39:36 amYes, that is on my list. I'm not quite there yet as far as troubleshooting but I'm definitely keeping it for when I am.

author: Ian.M
author_rank: Super Contributor
timestamp: September 24, 2020, 09:55:34 am
content: I never had that desire as my first scope was dangerous enough on its own.I used to have aHartley model 13A10MHz dual trace (beamsplitter tube) all valve 'boatanchor'. It was actually fairly light weight for its age - i.e. it only needed one large fit rugby player or two normal people to lift it. IIRC you could get a 'tingle' off some of its front panel jacks.Instead, I busted open a wallwart to remove the bridge rectifier and built a line-powered 'octopus' curve tracer for it.

author: vk6zgo
author_rank: Super Contributor
timestamp: September 25, 2020, 03:08:10 am
content: Quote from: fsenseman on September 24, 2020, 02:06:57 amThe stuff from the Uni is more like hints on how to use the gear in their lab, & don't go very deeply.To get more useful instructions on 'scope use, look for the youtube videos from w2aew, as well as some of Dave's ones.An Oscilloscope is an amazingly versatile piece of equipment, which many never learn to exploit to itsfull capacity.

author: rstofer
author_rank: Super Contributor
timestamp: September 25, 2020, 04:06:49 am
content: Quote from: fsenseman on September 24, 2020, 02:06:57 amIf you have the time, check out Charlotte's thread:https://www.eevblog.com/forum/beginners/what-an-oscilloscope-recommended-for-a-woman-passionate-about-electronics/Top of page 7, Reply 150 before she buys the SDS 1202X-E but there are some useful topics before that.We go over a lot of stuff and it is not the usual squiggly line on a screen kind of thing. She doesn't have much in the way of signal sources so she is working her way through the User Manual, function by function.I said it there, I'll repeat it here: Get an Arduino Uno and then...Toggle a bit at some fast rate (maybe just a couple of millisecond delay between operations) and watch it on the screen. Get used to setting up the trigger. Maybe move the trigger point over to the left edge. You should certainly try Single Shot capture (or whatever your scope calls it). Basically, you push the 'go' button and it captures just one buffer full and stops the capture. This is THE most important function of a DSO.Now try PWM, like a motor speed control or LED dimmer. You will find the code for this, and the Blinky code for the previous experiment in the Arduino Examples code. Adapt the code to read a potentiometer and set the pulse width. I think this code is included as well.Try the PWM for an RC servo like you might use with a robotics project. Again, the code is given, all you need to do is probe the pins and play with the display.Now for a harder experiment, if your scope does ASCII decoding: Get the Arduino to send a string like "Hello" and get the scope to decode it. This will work better in Single Shot mode. You may need to move the trigger point to the left to have enough screen to decode the string.Extra credit 1: Get some device that uses the SPI protocol (like an ADC) and connect it to the Arduino. Use something that already has code. Decode the transaction . Study the code and the display until you truly understand how SPI works. There'll be a test later.Extra credit 2: Get another device that uses the I2C protocol and work through decoding that as well. I'm pretty sure there are examples for that as well. I2C is much more involved and is my absolute last choice as a serial protocol but it does work.OR, skip the Arduino and use a Raspberry Pi and this really neat kit:https://www.amazon.com/gp/product/B06W54L7B5There's a lot of stuff to learn with that kit and it all runs on a Raspberry Pi. I use the Pi 4 and I find it to be a pretty decent workstation.Here's a similar kit for (and includes) an Arduino:https://www.amazon.com/Freenove-Ultimate-Compatible-Programming-Electronics/dp/B08B4D5MV5The nice thing about the Pi kit is that all of the development is done on the Pi. It is both the development environment and the device under test.The Pi kit above doesn't include the Pi 4:https://www.amazon.com/gp/product/B07V5JTMV9https://www.amazon.com/gp/product/B07TSFYXBChttps://www.amazon.com/gp/product/B06WWQ7KLVhttps://www.amazon.com/gp/product/B07VD568FBPlus you need a monitor with HDMI input plus a keyboard and mouse - I prefer wirelessHere's a cheap one:https://www.amazon.com/gp/product/B07BF3LFN3If you spend the time to do these experiments, you will be well on the path to understanding a scope.Cost wise, starting with the Arduino would be preferred. Education wise, the Pi is probably the way to go because it forces you to learn Linux (if you aren't already using it) and the code is written in C/C++ and Python. Good things to know!

author: Doctorandus_P
author_rank: Super Contributor
timestamp: September 25, 2020, 07:53:55 am
content: XR2206 has been obsolete for 10+ years or so, maybe twice that.The cheap kits from china have fake XR2206 chips. They do sort of work, but have some significant flaws, which are documented somewhere on the 'net. I think one of them is that the chip gives up with a supply voltage over 6V or so. (or was it 8V).The basics of a scope are pretty simple, and you've figuered them out already. It's mostly: stick your probe into something and twiddle the buttons until you have a stable signal on the screen. Most important are timebase, voltage and triggering. Most scopes have switchable 1:1 / 1:10 probes, which is a bit of a nuisance. Just glue the button in the 1:10 position, and you have one less button to worry about.Did you already do the probe compensation with the square wave on the scope?

author: fsenseman
author_rank: Newbie
timestamp: September 25, 2020, 11:14:37 pm
content: Quote from: Doctorandus_P on September 25, 2020, 07:53:55 amYes, I did. I've learned quite a bit so far, and much left to learn still.

author: fsenseman
author_rank: Newbie
timestamp: September 25, 2020, 11:19:57 pm
content: Quote from: rstofer on September 25, 2020, 04:06:49 amYes, I have Pis and an Arduino. I've also got a cheap logic analyzer to add a little more functionality to my bench. Actually decoding serial from the Arduino, from some code uploaded to it from the Pi, while the PI was being managed over VNC from my windows box, was more entertaining then the sine wave! I'll check out all the info you've suggested, it all sounds very interesting and should help me on my way. Thank you!

author: fsenseman
author_rank: Newbie
timestamp: September 26, 2020, 12:29:57 am
content: Quote from: vk6zgo on September 25, 2020, 03:08:10 amThanks for the recommendations. Yes, the pdf I linked is based on basic usage in the lab it seems. It's certainly given me more info than sticking my probes into the mains though! I'll check out the vids once I've gone through that pdf. I take my time and really try to figure this stuff out. I'm hoping that perhaps some other noob will stumble upon this thread and get some good guidance just as I have.

author: rstofer
author_rank: Super Contributor
timestamp: September 26, 2020, 01:31:58 am
content: Quote from: fsenseman on September 25, 2020, 11:19:57 pmI use that configuration myself from time to time. Now that I have a place to park the Pi with a 27" monitor, I don't use VNC as often.I am a huge fan of the Digilent Analog Discovery 2 and I have the Waveforms software set up on the Pi. I can write the code and scope the output all from the same device. I can also use the Digital Discovery as either digital IO or as a logic analyzer.I bought one of the cheap logic analyzers a couple of weeks ago via eBay. It works well on the Pi but I wouldn't jump for joy over PulseView. Having a logic analyzer, cheap or not, is quite helpful. I also have a 32 channel 200 MHz LA based on an FPGA. Works well! In fact, I probably couldn't have gotten my FPGA CPU running without it.Since you have the Pi, I would suggest the Pi Starter Kit I linked above. I don't know why, the Arduino kit does the same kinds of things but maybe because Linux has a full network stack. I did a web based LED switch project and had my grandson toggle the LED from his cell phone miles away. Pretty cool stuff!

author: fsenseman
author_rank: Newbie
timestamp: September 26, 2020, 01:43:05 am
content: Quote from: rstofer on September 26, 2020, 01:31:58 amHa! I hadn't got to that link yet (the starter kit). I have that kit and I'm working through it. However, I got about 3 steps into it and decided I needed a scope. So here we are, lol. It all started with WTF is a pull up resistor and why do I need one. Not being content to just take their word for it I had to see it. Hence, scope. Actually I downloaded the instructions for the Arduino kit and started with some of those projects as well. Got stuck right away because the RGB led in the Pi kit was a cathode and the project in the Arduino kit was an anode type (Or perhaps it was the other way around.) That's how I learned about the differences there.Rabbit holes, everywhere. I'm going to check 'em all out!

author: Electro Fan
author_rank: Super Contributor
timestamp: September 27, 2020, 03:07:00 am
content: Quote from: fsenseman on September 26, 2020, 01:43:05 am“Rabbit holes, everywhere. I'm going to check 'em all out!”If TEA had a theme song that could be a candidate for the song’s title, or at least a couple of the key lines in the lyrics.