My first LAB but what cable and what not? - Page 1
Forum section: electronics / testgear

author: FriedMule
author_rank: Frequent Contributor
timestamp: January 12, 2019, 03:30:36 am
content: First sorry for this non informative question, but to be honest, I do not know what to ask, how to ask or what to tell you so you have the best info.As the titel says, I do need what a decent lab need of cables, plugs, adaptors and I don't know.My problem is that I have no idea on what I need, why I do need some of it and I have no idea on what to ask, look for or avoid.My lab will be a 4 ch 350MHz scope, PSU (31V 5A), bench multimeter, universal counter and a 150-300W load with screw-connectors.I think that I will most of the time work with stuff below 200MHz

author: james_s
author_rank: Super Contributor
timestamp: January 12, 2019, 04:13:49 am
content: The first thing you need to do is decide what it is you want to do, then it should quickly become apparent what cables you need. The stuff I use most often are a collection of wires with good quality alligator clips on the ends. After dealing with a lot of bad quality ones that caused problems I bought some 18AWG silicone wire from a hobby supplier and made my own.

author: FriedMule
author_rank: Frequent Contributor
timestamp: January 12, 2019, 04:29:29 am
content: So the best is to do a project, find out what I need to measure in that project and get the cable?I have looked for coaxial cables that are thin and managble. mouch like probe leads but found out that there are over "a million" combination on data for capacity, resistance, Hz, shielding and a lot more. How do I know what to look fore as general cables for "whatever" in the future?

author: james_s
author_rank: Super Contributor
timestamp: January 12, 2019, 04:46:03 am
content: Coax is normally for rather specialized projects, other than some RG6 and a few RG58 BNC cables I don't keep a stock of RF cable around.For measuring you don't typically need cables, just use a scope probe on your scope. If you have a scope without probes then post the model and someone can suggest appropriate probes for it. If you don't have any projects in mind there's no point in buying stuff.

author: Inverted18650
author_rank: Frequent Contributor
timestamp: January 12, 2019, 04:57:20 am
content: I bought a large roll of 8-32AWG gauge high temp, super flexible, silver tinned, stranded cable, the high end silicone, from a Chinese supplier when I decided I was going to to the home lab. I spent about $300 and got 30M of each (all 13 sizes), in black and red, and it was the best investment I've made for the lab. I actually still have so much that I can share some with you if you'd like, but I will also try to find her contact info for you.Then for coax I found an auction site and scored some high grade commercial cable dirt cheap. Triax is like gold so best wishes. Talk to TiN and he can make you any custom cables you need as well.Cheers and best wishes mate

author: FriedMule
author_rank: Frequent Contributor
timestamp: January 12, 2019, 05:20:50 am
content: Wow thanks for your reply and offer!! :-)I am buying the Rigol MSO5000 4ch 70MHz scope (+"upgrade") and it has BNC connectors to it's functions generator that I'll later will upgrade to maybe a Siglent.Am I right in understanding that coaxial cables are about okay, no matter type then? Have heard Dave talk about crappy coaxial cables and then used an other type that worked much better.

author: 0culus
author_rank: Super Contributor
timestamp: January 12, 2019, 05:37:35 am
content: I spent a little $$ and got a nice set of Pomona RG-58 50coax with BNC for my lab. They are a little expensive but the cables are nice and flexible and have generous strain relief.

author: Inverted18650
author_rank: Frequent Contributor
timestamp: January 12, 2019, 05:52:16 am
content: Anything "will work" but listen to Dave's chat again, so you make sure you know the differences. To be clear, I didn't buy cheap /crap coax. I got lucky and bought very good, very expensive, industrial grade coax, very cheap.

author: FriedMule
author_rank: Frequent Contributor
timestamp: January 12, 2019, 06:05:51 am
content: You are 100% right and I'll do that, my "problem" is only that I do not know what make one coaxial better then an other. What shall I look fore? :-)

author: DaJMasta
author_rank: Super Contributor
timestamp: January 12, 2019, 06:54:49 am
content: Unless you can test it, you have to rely on advertised specs and the trustworthiness of the seller. Honestly, though, I wouldn't be too worried at 300MHz bandwidth or so. Yeah, it's fast, and yeah you can get crap cables/connectors which die quickly and don't meet their spec, but I don't think you need to look beyond standard BNC connector cables (male to male). Then you have your probes and jumpers... getting some banana jack cables are good with the PSU, but ones that are spring hooks on one end make them easier to connect to a lot of gear.From the real basic stuff, yeah just accumulate as you find a use for it. You'd do something where you want to split a signal and you'll want a BNC tee connector... or something with a 50 ohm terminated signal and you'll need a 50 ohm load to put on that tee. Or maybe you'll want to connect to something SMA so you need an SMA to BNC adapter or adapter cable, etc. You'll end up with plenty if you do enough stuff, but there's no sense in buying it just to have it on display. Stick with a bare minimum set and then see where it takes you.

author: hwj-d
author_rank: Frequent Contributor
timestamp: January 12, 2019, 08:17:35 am
content: My tip is:don't buy anything in advance just like that on suspicion!Equipment requirements only become apparent when real demands are made. If you don't know in the moment, in every moment, what you really need, wait till you have a real project, that will tell you.Some other tips, also use YT!For the RG-58 scope measurements, look what 'w2aew' can tell you with his channel. Beware of cheap chinese cables and (T-) connectors!Good luckEdit:without wanting to do advertisinghttps://www.ebay.com/sch/f-t-2000/m.htmlhas usually quite good things.

author: FriedMule
author_rank: Frequent Contributor
timestamp: January 12, 2019, 09:16:12 am
content: Yes no reason for buying a truckload of "maybe I may use that some time" but also no reason to hope and trust what the marketing says abut there products:-)What I am looking fore is maybe something like Probemaster where it is fairly okay prices and you know that it is quality but for the other items I may need.Just so I know that is okay and not have to ask if that or this is as "they say".

author: tautech
author_rank: Super Contributor
timestamp: January 12, 2019, 09:27:01 am
content: You can get away with bugger all to start with but what's between your ears and knowing how to use it is far more important.Once you get some 'good' gear and investigate nV, nA or at the other end, KV and GHz don't skimp too much on quality.Many eBay and Aliexpress accessories are that cheap you can afford to buy just small lots and if you like what you get buy more.

author: hwj-d
author_rank: Frequent Contributor
timestamp: January 12, 2019, 09:33:09 am
content: So in this case, this is what dave adds to his EEVblog 121GW Multimeter. Mine consider very good.https://www.ebay.com/itm/Brymen-Silicone-Gold-Plated-Test-Leads-Probes-for-Multimeters-CAT-IV-1000V/171162377470

author: tggzzz
author_rank: Super Contributor
timestamp: January 12, 2019, 09:45:07 am
content: Quote from: tautech on January 12, 2019, 09:27:01 amPrecisely.There's a learning curve associated with everything you buy, and the time taken to learn is time not working on your goals. Corollary: the less you buy, the faster you can get back to your goals.Obviouslysomeequipment needs to be bought and learned, but it is worth choosing tominimisethe learning curveIn the OP's case, I suspect it is worth learning about scope probes - both the different classes, and how to use them effectively andsafely. He can start that via the references inhttps://entertaininghacks.wordpress.com/library-2/scope-probe-reference-material/

author: FriedMule
author_rank: Frequent Contributor
timestamp: January 12, 2019, 02:37:16 pm
content: You are pointing on the most important, when talking about learning curve.My thought is that if you unknowingly choose some bad cables, plugs and connectors, you do not only struggle with finding out what does what but you also have to fight noise and bad connections due to sh*ty connections. Much like learning to solder. If you are new at that and have leadfree solder, iron with power cord in the end and the wrong tip, you are guaranteed to have a wary hard time, while cheap 60/40, a soldering station and the right tip can make your learning curve a lot easier! :-)

author: tggzzz
author_rank: Super Contributor
timestamp: January 12, 2019, 02:43:42 pm
content: Quote from: FriedMule on January 12, 2019, 02:37:16 pmYes indeed. And along those lines, the best advice for a beginner is that they should avoid that work of the devil: solderless breadboards. Youalwaysend up spending more time debugging the breadboard than you do debugging your circuit.Muchbetter to use rats-nest and manhattan techniques.

author: james_s
author_rank: Super Contributor
timestamp: January 12, 2019, 07:41:49 pm
content: I use both techniques, solderless breadboards work just fine, *if* you understand the limitations. If you try building RF circuits on a solderless breadboard you will probably spend a lot of time going in circles, but if you want to blink some LEDs with a microcontroller or tinker around with a bunch of different sensors or something it would be a bit silly to deadbug that.In most cases understanding the limitations of a tool, how to use it well and when to use one tool vs another is far more valuable than the specific details. On a rally course a champion race driver in a stock family sedan will run circles around a novice in a high performance race car. An experienced engineer can accomplish more with primitive gear than a novice with a state of the art lab.

author: tggzzz
author_rank: Super Contributor
timestamp: January 12, 2019, 08:20:51 pm
content: While I agree with your second paragraph, I disagree with the first.In addition, beginners won't know the obvious and subtle ways in which solderless breadboards waste your life.

author: FriedMule
author_rank: Frequent Contributor
timestamp: January 12, 2019, 10:52:01 pm
content: I do not know if I am right here but I do use use both breadboards, perf board and "home cooked" boards.breadboards for testing if it at all can work or just make fire. :-)perf board to test if values and components really do what I hope"home cooked" if what I do demands a greater control before ordering "the real thing".but to avoid that in connectors and cables, I'd try to get "the real thing" from start, and there have to be, I hope, some brands that are okay but do not demand you to sell your mother. :-)

author: nctnico
author_rank: Super Contributor
timestamp: January 13, 2019, 02:11:37 am
content: Quote from: FriedMule on January 12, 2019, 03:30:36 amI'd start with 4mm banana leads (silicone jacket) with stackable connectors and BNC cables. You can buy decent BNC cables with RG316 coax from Ebay very cheaply. Rg316 is thin and flexible so it is easy to work with. I often cut these cables up to connect a circuit to a function generator or scope (without probe). Furthermore some BNC T splitters and BNC to banana (and reverse) will come in handy.Just buy cables. Making them yourself is a waste of time.

author: FriedMule
author_rank: Frequent Contributor
timestamp: January 13, 2019, 05:01:58 am
content: Thanks I'll look at that cable!I have found some specifications on coaxial cables, what is important and what do they mean? :-)Type (/U), MIL-C-17, Z0(Ω), Dielectric, Type, Capacitance (pF/ft), O.D. (in.), dB/100 ft @400 MHz, Shield (braided, foil, ...)

author: james_s
author_rank: Super Contributor
timestamp: January 13, 2019, 06:26:46 am
content: Quote from: tggzzz on January 12, 2019, 08:20:51 pmI got my first solderless breadboard when I was 8 years old, I never stopped using them, never really had any problems at all. Once I even built the majority of a ~600W SMPS on one, with only the 400V bulk filter caps and rectifier being external. I would never recommend doing that but I did it and it worked. Obviously they are not a good choice for RF or high power stuff but for typical hobby circuits they work just fine. TLL ICs, transistors, microcontrollers, op-amps, quite a few hobbyists never build anything that wouldn't work on a breadboard. If one's interest is in RF and radio stuff then it should be obvious that there are better choices.

author: tggzzz
author_rank: Super Contributor
timestamp: January 13, 2019, 09:10:21 am
content: Quote from: james_s on January 13, 2019, 06:26:46 amMy experience is the opposite. If I was a beginner, my circuit failing for unknown reasons would discourage me.Unfortunately standard logic (let alone high speed logic such as 74lvc1g) generates UHF components and causes problems in typical breadboard circuits.Quite apart from the, ahem, variable resistance of the contacts, the inductance of the hookup wires is a problem with switching transients. Do some calculations about the ground bounce; with some packages that can be a problem even on PCBs!

author: james_s
author_rank: Super Contributor
timestamp: January 13, 2019, 06:31:35 pm
content: I don't know what to tell you, maybe you're doing it wrong? Maybe you had unrealistic expectations? Maybe you had a cheap or faulty breadboard? Maybe you've never actually used one? I have no idea, all I can say is that millions of people like myself have successfully used solderless breadboards for decades without problems.

author: nctnico
author_rank: Super Contributor
timestamp: January 13, 2019, 07:31:01 pm
content: The solderless breadboards come in a wide variety of qualities. I have used them in the past but connecting all the wires becomes tedious quickly and you need to use clean component leads. Nowadays I just make a small PCB which is also easier for SMD components. I rarely use thru hole components.

author: tggzzz
author_rank: Super Contributor
timestamp: January 13, 2019, 07:43:39 pm
content: Quote from: james_s on January 13, 2019, 06:31:35 pmAh yes, the "I haven't had problems so there aren't problems" argument. But many have, and many do get subtle problems.I suggest you do a few LTspice simulations where you include parasitic inductance and capacitance. I'll do one for a digital circuit.Consider the ground bounce in a 1" wire (i.e. includes hookup wire and bond leads inside the ICs), the rule of thumb is 1mm of wire has 1nH of inductance, so 25nH. In most solderless breadboard lashups the wires are much longer, so I'm being generous.Assume 8 digital outputs driving eight 5pF loads (i.e. 40pF in total).Assume a leisurely 10ns transition time.Assume each driver has 50ohms output resistance (modern jellybean CMOS is more like 7ohms, so I'm being generous!), so eight in parallel are 6.25ohms.In the picture below, V1+R1 are the output drivers, L1 is the ground lead inductance, C1 is the load capacitance. Vg represents the ground bounce that is seen somewhere in the circuit (exactly where depends on what you regard as zero volts).As you can see, even this crude simulation indicates spikes sufficient that the analogue voltage might not be correctly interpreted as a digital signal.N.B. such things were a problem for some octal buffers, even when correctly mounted on well-designed PCBs!I invite you to do something similar for analogue circuits, e.g. a simple comparator or amplifier.

author: _Wim_
author_rank: Super Contributor
timestamp: January 13, 2019, 09:11:11 pm
content: Quote from: nctnico on January 13, 2019, 02:11:37 amI think the above is very good advice, would have recommended almost the same.I would also add that for "normal" use (no Ghz, KV,nA,nV...) many of the low cost adapters, cables etc from china are very useable. I personally would recommend to buy some small collections of the various items in the attached picture (this is partly what nctnico, I added some rca to bnc adaptors for some audio stuff, some male bnc-bnc connectors that are very useful to attached to the end of a bnc-bnc cable to attach any of the other adaptors and the bnc to screw terminal adaptors).As these are so cheap (25€ gets you already a nice collection) it is very handy to have them around, because when you realize you need some during a project, you do not want to wait on ordering these.

author: MarkF
author_rank: Super Contributor
timestamp: January 13, 2019, 10:02:19 pm
content: I would just start with a small assortment and see what you tend to use.Here is a list of cables I have on hand. You might want some BNC T's and 50 Ohm termination later on.Test Lead Set & Alligator ClipsTL-21 Mini Grabber for IC Test LeadsBanana to Mingrabber SetBanana to Alligator SetBanana to Banana SetBNC Test Leads SetI would also get a few Solderless Breadboards.830 Point Solderless Prototype PCB Board Kit(a better brand than these)

author: tautech
author_rank: Super Contributor
timestamp: January 13, 2019, 10:22:17 pm
content: Quote from: MarkF on January 13, 2019, 10:02:19 pmIf you restrict bread boarding to just proving a 'building block' then a couple is enough for most projects.That way daisy chaining all yourprovenblocks together at the PCB design stage generally works fine.Here's an example of what can be done with a few:https://www.eevblog.com/forum/projects/cloning-a-tandy-trs-80-model-1/msg2101375/#msg2101375

author: hwj-d
author_rank: Frequent Contributor
timestamp: January 13, 2019, 10:41:37 pm
content: Quote from: tautech on January 13, 2019, 10:22:17 pmThat's nothing. Look, what you canrealdo:

author: james_s
author_rank: Super Contributor
timestamp: January 13, 2019, 11:44:53 pm
content: It's quite possible to build rather complex circuits that work fine. They don't have to be a complete rat's nest either. Since I'm able to prototype circuits on them without problems, all I can guess regarding those who can't make them work is that they're using inferior breadboards or using them wrong or for the wrong sort of projects.http://searle.hostei.com/grant/6502/Simple6502.htmlhttp://searle.hostei.com/grant/spaceInvaders/index.html

author: FriedMule
author_rank: Frequent Contributor
timestamp: January 14, 2019, 01:22:59 am
content: Oh oh and then some ketchup:-)I really like your advices, I can understand that below 1GHz it is not so important what I get, as long it is not made down in the bicycle garage south of Hong Lo.I hope that it will be ok if I'll look at your links and then return with a list of "what I thin I need", so you can judge if that is ok?

author: FriedMule
author_rank: Frequent Contributor
timestamp: January 16, 2019, 01:06:45 pm
content: I have found some cable that should be great:-)The decription is: CBL ASSY BNC PLUG RG142 Cable Assembly Coaxial BNC to BNC Male to MaleDo not know if that is enough for anyone to say if that type of coaxial cable is fine for general usage?

author: nctnico
author_rank: Super Contributor
timestamp: January 16, 2019, 02:34:09 pm
content: RG142 is too thick and sturdy which makes it a nuisance to use in test setups. I really recommend to get RG316 cables for general purpose use (<1GHz).

author: hwj-d
author_rank: Frequent Contributor
timestamp: January 16, 2019, 03:09:54 pm
content: Quote from: james_s on January 13, 2019, 11:44:53 pmYes, ok. For the very first.But in 2019, for the second, take KiCad, osh a pcb for such things.

author: tggzzz
author_rank: Super Contributor
timestamp: January 16, 2019, 03:56:26 pm
content: Quote from: james_s on January 13, 2019, 11:44:53 pmYes, it is possible to cross the Rockies/Alps/Himalalays on a push bike. That doesn't mean it would be a good choice, especially for some that is learning to ride a bike!QuoteAnd what happens when abeginner'scircuit doesn't work as they expect? Is it the breadboard, the technique, the circuit, or the beginner's understanding of the circuit?Those questions (and problems) can be minimised by using better implementation techniques, especially manhattan and rat's nest.

author: FriedMule
author_rank: Frequent Contributor
timestamp: January 16, 2019, 09:13:32 pm
content: Quote from: nctnico on January 16, 2019, 02:34:09 pmI am glad for your help. If we take the cable I did tought as ok, how much thinner is the RG316?

author: tggzzz
author_rank: Super Contributor
timestamp: January 16, 2019, 09:23:37 pm
content: Quote from: FriedMule on January 16, 2019, 09:13:32 pmThat is easily foundhere.What's just as important is the flexibility. You wouldn't want hardline coax

author: nctnico
author_rank: Super Contributor
timestamp: January 16, 2019, 10:32:58 pm
content: Quote from: tggzzz on January 16, 2019, 03:56:26 pmStill the problems with ground bounce are not a big problem for slower logic. In the past they build large logic circuits using wire-wrap. Not prototypes but production hardware! I recall messing around with a magnetic tape spool machine controller to hack it a little bit.

author: tggzzz
author_rank: Super Contributor
timestamp: January 16, 2019, 11:10:08 pm
content: Quote from: nctnico on January 16, 2019, 10:32:58 pmIn the mid 80s there were some notorious TTL ics w.r.t. ground bounce - even on PCBs with groundplames. They weren't fast!The devil is in the details, and solderless breadboardspreventdecent construction details.

author: tggzzz
author_rank: Super Contributor
timestamp: January 17, 2019, 07:19:23 pm
content: Quote from: nctnico on January 16, 2019, 10:32:58 pmYes indeed. The computer I used for my final year undergrad project, a Modcomp4, was wirewrapped. And I still have wirewrap kit, and occasionally use it.But that doesn't validate your point.You probably don't remember the "surprising" technology people had to resort to, e.g.Rogers MicroQ flat capacitors placed under ICs, often retrofitted when problems aroseIC sockets with capacitors built into themand I doubt anybody would use those with solderless breadboards!