I went through this exact process last year when I decided to go back into electronics and to get a second degree, in EE. I'm surprised at the amount of nerd-rage generated when someone dares to ask for advice when they want to spend more than a few hundred dollars, without "earning it." I ignored this nonsense and evaluated each purchase. I'm now using my gear for freelance projects and just ordered a Keithley 8820-S this morning to work on a customer project.
View Dave's video. Look at suggestions, then upgrade where you see fit. That's exactly what I did-- I built up a list and would research the test gear to death and purchase each, one at a time.
My advice to you or any beginners in general:
- If you don't know you need something don't buy it, or buy the cheapest one you can get your hands on. When you NEED it, get the best you possibly can afford, for your specific and future needs.
- Don't pay retail for new equipment. Don't be afraid to get a quote or ask for a discount. The more you buy, expect the discount to be bigger. That being said, TEquipment usually had the best deal when I was shopping for new gear and soliciting quotes.
- Sometimes eBay has worse prices than you can get from an factory authorized seller; Sometimes prices on Amazon are worse, as there are sellers on Amazon who will take your order and use eBay as a drop shipper. Always shop around.
Power supply:
- Forget programmable, focus on cheap and reliable. Chances are you won't ever use the programmable features anyway. By the time you really want a programmable power supply, they will all have 6.5 digit meters built in with LXI standard. Also, I've never had to run my power supply above 24V, so don't go crazy. Minimum should be a linear power supply with current limiting. Check out factory certified/used power supplies and you might find a bargain. I purchased a new Tektronix 0-72V power supply on clearance for ~$323.
- The Rigols have had some major issues, am I'm not convinced they've all been fixed; same with Siglent. Mayuono has a cheap power supply with a built in 6.5 digit meter, but is known to generate a destructive 15 V spike when turned on or off. Or just go to tequipment.net->power supplies and sort from lowest the highest and keep scrolling until you find one that you are comfortable with.
- You can build your own power supply, but after spending hours and hours looking at kits, designs, parts lists, pricing out components, figuring out how to make the case, and trying to find a design with CV/CC and limiting was consuming too much time. You can purchase a power supply and it will arrive in a few days ready to go. Yes, it's a great learning experience, but keep in mind most shops don't design power supplies for their products, they buy them off the shelf or tweak reference designs from places like TI.
- Choose wisely and the power supply will outlive you, so long as you don't abuse it. You'll notice Dave still has his first power supply.
Logic Analyzer:
- You don't need one unless you are working with digital designs serial busses. When you want one, buy just a Salea logic analyzer. The logic analyzers on scopes aren't great.
Oscilloscope:
- Avoid USB oscilloscopes, or multipurpose USB test stations like the NI MyDAQ, or Analog Discovery. I was forced to purchase a NI MyDAQ for one of my EE courses and it's an expensive toy that was forced to use with terrible, bloated software that only runs under Windows. The people recommending them never touched one.
- Don't buy an antique/analog oscilloscope unless you just want to collect and repair old stuff as a hobby. Be nice to people who do this, because a) they know magical stuff about analog design, and b) you might inherit their stuff when they go into the old folks home, and I guarantee they have some cool stuff hiding in cardboard boxes that they've forgotten about.
- Rigol is the #1 recommendation for <$500. Beyond $1k, they aren't as good a value. I purchased the cheapest Rigol. It got the job done, but it was noisy, flickered constantly, and had issues. Now that I have more experience, I honestly think I would have been happier with an entry level scope from Tektronix, Agilent, etc., for just a little more money. But every time I thought about buying an entry level scope from the top tier vendor, I'd see people complaining about the limited memory. I can count the number of times on my right hand the times that would have mattered, provided I set the triggers correctly. But the bright side is that it was terrible enough to push me to upgrade. As soon as I had the smallest justification, I upgraded to an Tektronix MDO3014. I am very, very happy with the new scope.
- Above the $800 price point start looking at other manufacturers. Hammeg/R&S has some low end scopes that looked pretty good against the Rigols if you get them on a sale. Keysight too.
- When looking purchasing your first oscilloscope don't get caught up on extra features, look at primarily at bandwidth and what you intend to do, and the rest will follow. In the beginning most of your measurements are going to be qualitative (is it 12V or 0V, what does the waveform look like, etc.) and not quantitative (how many nano seconds is the rise time compared to that other signal, how many mv is that signal before the clock arrived, etc.).
- For very basic electronics or basic repair, an oscilloscope is unnecessary but nice to have.
- For basic electronics when you start throwing in digital logic, op-amps, I'd say <=50MHz is fine.
- For basic microcontrollers, look at the signals you intend look at. Still, I think 50MHz is fine, unless you start getting faster clock speeds.
- More bandwidth is better; lower capacitance probes is better; 10x passive probes are better than 1x/10x probes.
DMM:
- Get two DMMs; two cheap DMMs are better than one expensive one; eventually you will want to measure current and voltage at the same time or check to see if the meter is broken.
- I think a 5.5 digit meter, like the Fluke 8808A is awesome; it's fast and crazy responsive. I purchased a factory certified one from Fluke for ~$800. I also have a 6.5 digit meter, and an 87V, but I use the 5.5 digit fluke most often.
LCR meter:
- This is a luxury. Since I was buying parts assortments I wanted to be able to measure capacitors and unmarked inductors. Don't buy the $20 LCR/ESR meters on eBay, they are worthless. Buy the BK LCR meter or similar.
- Also, don't buy jumbo mystery component grab bags, or you will end up with a drawer filled with hundreds of parts you don't use. If you want to buy an assortment of parts, buy an assortment of labeled known values. Trust me. I have a box of unknown chips with part numbers that don't reference to anything.
Function Generator/Arbitrary Waveform Generator
- Resist the urge to purchase the newest Siglent or Rigol waveform generator. I'm still using the cheap Instek function generator and just now getting to the point where I want to use arbitrary waveforms and noise injection. When it becomes obvious you need one, buy a good one.
Soldering
- Buy a reasonably good soldering station with replaceable tips. I'd suggest Weller, Hakko, Metcal, etc. You want variable temperature control; leaded and lead free solder melt at different temperatures, and the thermal mass changes depending what you are soldering. Get a thinner pencil tip so you can do through hole and SMD with drag soldering.
- small diameter solder.
- good desoldering braid with a fine mesh.
- liquid flux is your friend (kester flux pen or in bottle)
- For Hot air, I'd recommend Hakko. They seemed to have the best price when I bought mine.
Etching/PCB fabrication
- While many will tell you just to send the board out and have it manufactured, I etch my own boards and am now playing with applying my own solder mask and using the toner transfer method for silk screen. You can wait five days to get a pretty board from a PCB manufacturer or spend two hours making a board. Its up to you. You can also etch your own solder stencils as well.
Prototyping
- If you are using breadboards, buy the flexible jumper wires. Don't buy the precut wires, but the flexible ones. Buy mostly male to male, but purchase some male to female and female to female. These are handy when you have exposed headers but need to connect to a female logic analyzer or female header. If you have a cat, buy twice as many as my cat likes to chew them to pieces if I leave them out.
- Cables are handy. Buy BNC-aligator, BNC-BNC, BNC to mini-grabbers, mini-grabbers to mini-grabbers, post to aligator... you get the idea.
Spectrum Analyzer:
- You don't need one.
VNA
- Seriously, you don't need one. If you want to know what one is, find one of the analog scope guys (see above) and offer to clean the cat urine and dead mice out of their garage of analog oscilloscopes and they will teach you what they are. If they give you one of their scopes, graciously accept it and rent a box truck to help you get it home, or they may get offended.
If you want to get into RF, disregard most of what I say.
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