Lab tools for a future Electronics Engineer - Page 1
Forum section: electronics / beginners

author: canibalimao
author_rank: Regular Contributor
timestamp: August 25, 2015, 08:56:00 am
content: Hi guys!I'm new here in forum and I would like to start my activity here asking for some opinions to buy some lab equipment.I want to get a scope, a function generator and a power supply.For the scope I thought about the Rigol DS1057Z, as I can get one new for "just" 340€ and I've read a lot of good reviews (specially the one from Dave on youtube). It is still the best low price scope in the market?For the power supply I think, for now, I'm just stay with a PC power supply, since I don't see myself using a variable one for now.My biggest issue is with the function generator. It's not mandatory as the scope or the PSU, but I found some cheap ones on eBay and Aliexpress and I want to know if they're a good first shot.Hope to get some help to start my journey spending money

author: canibalimao
author_rank: Regular Contributor
timestamp: August 25, 2015, 09:25:43 am
content: Quote from: TheElectricChicken on August 25, 2015, 09:16:09 amDon't forget that the quality/price ratio is very important too, right after the low price factor

author: fivefish
author_rank: Frequent Contributor
timestamp: August 25, 2015, 11:23:27 am
content: QuoteI suggest build your own simple PSU, if you don't want to buy a cheap/used one on eBay. Check out datasheet for LM317, build a simple adjustable PSU. (Some HP PSU's use the same 317 part, albeit with added extras like adjustable current, digital readout, etc... but the core concept is the same).

author: EEVblog
author_rank: Unknown
timestamp: August 25, 2015, 11:27:36 am
content: Quote from: canibalimao on August 25, 2015, 08:56:00 amYep.QuotePower supplies are fun to build yourself.QuoteYes, a cheap ebay one will do you just fine.

author: canibalimao
author_rank: Regular Contributor
timestamp: August 25, 2015, 11:37:54 am
content: Quote from: fivefish on August 25, 2015, 11:23:27 amBut those simples PSUs aren't limited in current and a bit noisier?But, now that I think a little bit about that, the current limit isn't a big issue since I'm going to use a wall PSU with about 2 or 3 amps...Quote from: EEVblog on August 25, 2015, 11:27:36 amThank you for all the simple answers. As soo as I proceed with the scope order I'll buy a couple of those cheap generators to have a bit of fun.

author: TheElectricChicken
author_rank: Frequent Contributor
timestamp: August 25, 2015, 11:41:27 am
content: Quote from: fivefish on August 25, 2015, 11:23:27 amIt's good advice. Learning electronics is a good way to learn electronics.I made one from old junk I found herehttps://www.eevblog.com/forum/beginners/using-diodes-to-reduce-voltage-by-1-2-v-under-a-very-high-load-%28e-g-20a%29/msg729436/#msg729436also, I bought a big printer secondhand for $1 and got many power supplies out of it. There is a picture here showing the labels on two power supplies which are identical components but different output. They have a very easy to spot variable resistor on them (potentiometer) which I might give a twist and test what voltage range it can output. if it seems nice, I should get a potentiometer with a knob on it so that I have a variable power supply and buy a $2 LED voltmeter from ebay so that it has a output voltage reading. For big accuracy, 5 digit output LED meters are about $4

author: canibalimao
author_rank: Regular Contributor
timestamp: August 25, 2015, 11:56:02 am
content: Wow those PSUs were inside or outside the printer? I have a really old printer on the basement connected to a Pentium MMX (windows 95) computer that might be usefullI just hope that spiders didn't kill the PSU

author: Shock
author_rank: Super Contributor
timestamp: August 25, 2015, 12:00:11 pm
content: There isn't anything hotter than a Rigol DS1057Z at the moment for an entry level new oscilloscope.I'd hold out as long as possible on the function generator and see exactly what you need, if you're studying most Universities provide equipment to complete your course but as you're probably aware having an oscilloscope to use whenever you need it and not have to compete for lab time can be an advantage.With that I see no harm in pulling the trigger on a $10 ebay special if you just need to work on getting comfortable with some waveforms initially, math and circuit troubleshooting. You can use any old laptop or PC (linux/xp, no exciting OS required) to use as a limited waveform generator and these are very easy to pickup freely after you put the word out. It can also double as a dedicated lab PC for little bits of software, development or to read the odd pdf.The other factor is determining what you need is where you intend to work or take your study further and what they typically provide. You wouldn't need to drop a pile of cash when your are going to be sitting in front of the same equipment at work day in day out. You just need to operate it, after you get the basics down that can be learned from the manual.Lastly is priority spending if you are on a budget you are going to have a whole pile of expenses so you want to consider what is the smallest amount to spend for the maximum benefit and unless you have money behind you, going into further debt to buy equipment that could be substituted by small circuits or a cheaper equivalent doesn't make sense unless it's guaranteed to land you the job.If you can handle the fact that most things you will ever need in life are on average within 2 weeks away from being delivered to your door, you only ever really need to plan a month ahead of time.

author: canibalimao
author_rank: Regular Contributor
timestamp: August 25, 2015, 12:13:26 pm
content: Thanks for the advices Shock.This lab equipment is just to stop going to university to test/debug my own projects. Sometimes I saw myself storing in the corner some projects so then, when I go to the university lab I can test more than one and solve more problems in a single "tour". Having the equipment at home I don't need to make these pauses...Besides this, I think that almost any Electronics Engineer should have some gear at home, even if it is just to show friends that he knows how that worksAbout the waiting time, I'm very familiar with that and that's why I just want, for now, these 3 tools. Some other equipments I already have at home and, what I don't have, I'll order as soon as I need it.

author: fivefish
author_rank: Frequent Contributor
timestamp: August 25, 2015, 12:24:47 pm
content: QuoteLM317: Max current is 1.5A. If you need more, you can tack on a power transistor (see datasheet).Ripple Noise is 0.003% of Vout.Real world, 10mVpp ripple+noise measured on a scope. Is that noisy? Will that amount of ripple prevent your project from running successfully?As I said, some HP bench power supply use the same 317 regulator chip. Look at their schematics in their service manual.Maybe I'm just old school, but my opinion is the 1st project anyone wanting to get into this hobby, or studying electronics at school/college is to build your own PSU first. If you have a PSU and a multimeter, and some breadboard and components at hand, you can already learn a lot about electronics. A PSU is a very simple 1st project! The only "critical" section here that may be nerve wracking for a beginner is the AC wiring.Scopes and signal gen are nice to have, but not absolutely necessary to learn electronics. They'll come in later, and you'll know when you need them.

author: TheElectricChicken
author_rank: Frequent Contributor
timestamp: August 25, 2015, 12:35:33 pm
content: Quote from: canibalimao on August 25, 2015, 11:56:02 amThey were inside the printer, the printer was very large, and it weighed more than I do !!! I often rip apart small printers of the type you have, in fact I rip them apart every single one I find ! There are often lovely stepper motors and timing belts suitable for building 3D printers with, and assorted other items.The best way to know what you'll get in the way of power supplies is to check the power consumption label on the device, it will give you an idea of the power of the transformer, rectifier and caps or switchmode supply if it has that instead. When one is advertised online a fast search will also give you the same information.

author: nowlan
author_rank: Frequent Contributor
timestamp: August 25, 2015, 12:36:03 pm
content: Steer clear of the industry power supply stuff.Either get an adjustable wall wart, or cheap chinese korad style.You already have butchered pc psu, so you have somethin to work with.As for function generator:1. The cheap DDS chip ones on ebay work, but need to be stopped to adjust the frequency. Not easy to sweep audio etc.2.FeelTech3. Siglent if you have money.4. Used analog function gen on ebay?5. Soundcard if you are testing audio equipment.

author: canibalimao
author_rank: Regular Contributor
timestamp: August 25, 2015, 12:54:47 pm
content: Quote from: fivefish on August 25, 2015, 12:24:47 pm1.5 ampscouldbe less than I need in some aplications. But, as I said, it won't be the biggest issue since I'll use a 12/24V PSU that won't deliver more than 2 amps.About the noise/ripple I saw a video on youtube once that told that. I just believed itYes, the AC part of a PSU is what gets me crazy. I get scared with all the projects that involve AC live wiringBut if I get a 24V PSU to connect to the variable PSU I don't have much problems.Quote from: TheElectricChicken on August 25, 2015, 12:35:33 pmOh ok. The one I have is nothing like a plotter, is just a HP Deskjet 690C printer. It isn't ripped off already because I don't want to toss it out and I don't have space to store the parts after the "surgery".Quote from: nowlan on August 25, 2015, 12:36:03 pmI don't want to get a chinese style PSU because I have already bad experiences with those. A 12V 1A once "exploded" in my hands while connecting it to the wall socket, with no load attached to it. Now I prefer to drop 10€ on one but with the right certificates.About the PC PSU mod I don't have one already, I just have plans to build one and I want to know if I should start from there or I should build right now a variable one.For the function generator, I don't have plans to use it with audio, but thatfeatureof the cheap DDS makes me think. Having to stop the generator every time I want to adjust the frequency is a bit lame...The used analog generators aren't very benefic to me because the shipping costs.Thank you all once again for all the time spent here!

author: ramueller11
author_rank: Newbie
timestamp: August 29, 2015, 11:48:22 am
content: Newbie here. I recently got setup with some basic tools myself.I was using an old computer power supply for the longest time to power my projects. They are very effective, especially with the LM317 and a decent RC input filter as suggested. One thing that is a potential problem with this route is that the computer power supply is earth referenced, which can provide some nasty ground loops. I've nearly cooked a prototyping board hooked up to the USB.I just recently picked up a proper one which I thought was a good deal: I found the 1960's vintage HP linear power supply, series 62xx, are a steal at about $30 delivered. (Not sure if this is what fivefish was the PS was referring to). The model I have (HP 6201B) provides 0 - 30 V at 1 A. From what I can tell, it has really clean power coming off - <0.5 mV ripple at about 20 MHz @ 3 VDC output. My opinion is that an old quality-made item from 'Murica beats a new china special at comparable price points, if digital output is negotiable. Then again, you can wack a cheapie digital multimeter in there and you are in business.Good luck!

author: SylvainP
author_rank: Contributor
timestamp: August 29, 2015, 09:39:25 pm
content: Do you have a multimeter? You should get one (or two) before getting a scope or function generator.

author: canibalimao
author_rank: Regular Contributor
timestamp: August 30, 2015, 11:09:59 am
content: Quote from: ramueller11 on August 29, 2015, 11:48:22 amAs far as I learned in this 6 years of studying electronics, this is so true! The good old electronics are much better than the new chinese ones.Quote from: SylvainP on August 29, 2015, 09:39:25 pmYes, I have one. My godfather offered me a "pocket sized" one when I started my course and, last year, I'be bought a UNI-T "auto-scale" one that consumes less power from the batteries