I have finally hit the wall - Page 1
Forum section: electronics / beginners

author: Krinkleneck
author_rank: Contributor
timestamp: August 12, 2013, 01:09:56 am
content: This is my proud moment, and also a slight to very wicked inconvenience. I am on the last project that I can scoot by with on small electronic test equipment. I am finishing up a 3D printer, but that's not the problem. The problem is that my next project is not only a little bit time oriented, but it requires equipment that I have been holding off on buying for as long as I can. My next project is to train my friend in more advanced electronics so that we can build an ARM cortex motherboard together to make the project progress smoothly and more efficiently. The equipment that I currently have is a self made bench power supply, worlds crappiest pseudo-oscilloscope (bandwidth of less than 1mhz), one decent multimeter, one cheap firecracker multimeter and one old computer that I won't let die. Since this new project is going to need a standard of tolerances and all around requirements. I would love and have to have my work stay under the 5% tolerance range. The equipment that I plan on buying is as follows.function generatorAnother 2 good multimeters2 current limited power supplies (assembly required to help my friend)a power supply specifically for low amperage (same as above)better antistatic protection mata digital oscilloscopean analog oscilloscopea lot more SMD's within the 5% range, and other SMD componentsand a whole new set of through hole components/logic chipsanother soldering ironThe point of the project is to be making a motherboard, and I am also making custom memory connections. This is going to be attaching to a tablet, or notebook. That's not the catch though. I am in the process of getting funded for the project. It's under review right now. I start working on this in 6 months so long as it is approved. Once everything is cleared I am getting paid to make the design, finalize the object, and make it simple to replicate (think of this as more of a grant than an actual job). I am searching through the different sites for a proper oscilloscope. I need something that is digital, and can read a bare minimum of 500mhz. It is important for it to have multiple channels, but a logic analyzer is optional. Most of the work in the beginning will be simulation. Then I will order the designed boards since I don't have the equipment to make PCBs of that size, quality, or quantity. So for the sake of time, energy, sanity, and money it would be easier to order these boards. If there is any equipment that you recommend to be added that I am missing from what is mentioned that would be great.Mind you I will be searching while this is posted (I also have been up relentlessly because of the possible approval so forgive any tired mistakes). So this might get removed before anyone has a chance to respond

author: free_electron
author_rank: Super Contributor
timestamp: August 12, 2013, 02:11:46 am
content: Quote from: Krinkleneck on August 12, 2013, 01:09:56 am1) useless for what you are doing.2) why 2 ? how many voltage/currents are you going to monitor ? you already have 2 meters. get 1 good one.3) get a few used 3410 or 3411 power supplies on ebay. perfect for what you will do.4) analog scope ? eliminate that. invest in a good mixed signal scope , or a 4 channel scope and a simple USB digital grabber like a salae5) why buy a whole pool of parts? just order what you need. it's useless to have a huge stock of parts. to give you an example. i just designed the power supply section for my new book. i have exactly 1 diode and the smd resistors and caps in stock. The other 33 components i had to order. Why ? because what i had was either the wrong working voltage, the wrong size for my liking ( i am limited in board size and everything has to fit) , or otherwise not fit for purpose.sure , you can get some resistors and caps in stock , but don't overdo it. once you get to designing the final board, then pick the final parts that fit exactly the design.6) get a good soldering iron this time. like a metcal or a weller.sure i had capacitors in stock ,but this thing requires VDE and UL listred capacitors approved for line voltage use as well as X1 and Y1 capacitors. same for the high voltage caps. i had only 15mm wide ones in stock. Too large so i needed to order 12.5 mm ones. even the output caps i had 470uf 16v were 12mm generics and i needed 10mm diameter , tall capacitors for switching purposes. same deal with the optocoupler. i have tons of optocouplers ,except VDE and Ul listed wide body (400 mil as opposed to 300mil ) ones... and then there is the special fast switching diodes, transils , common mode chokes, the power ntc, the molex connectors , the bussman fuse. i have an extensive stock of parts , but none fit this design... there was always something wrong. wrong size, wrong pitch , wrong voltage. Some were even plain obsolete... so useless to design them in as the new parts will have different pin pitch ( i had some caps with a 12mm pitch. nobody has those apparently. its all 10 , 7.5 or 5 ...

author: Krinkleneck
author_rank: Contributor
timestamp: August 12, 2013, 02:40:56 am
content: I am not just doing the job, but I am completing a lab.I am getting two extra so that I have two, and my friend has one. It also follows my N+1 philosophy. This is to insure that if it accidentally breaks or gets misplaced I have a spare floating around. I have on many occasions also had the need to measure multiple points that can be a pain to do with one.I'll keep those in psus mindAs much as I admire the modern usb scopes, the function of a good benchtop scope can't be beat. A few tektronix scopes have caught my eye, and they are within my budget and call for what I need. I will also need it for other projects, repairs, and designs. The analog is for that N+1 rule again, but I am not spending near the amount.No, I need have a nice stock of components. When I am not making circuits, I am repairing different things. If I have a nice back stock it can make repairs go a lot smoother than ordering. I have done the small buys at a time. Over time it cost me more than determining what you need based on previous work. If you buy in bulk based on what you need, and a little insurance, it's hard to over spend. This is because you are only restocking when you run out, and not every time. Plus you can only get so many components from scrapping.I do have a good soldering iron, but I just need another one. Two irons are useful for SMD component removal.I am not going into details on the little tools that I am adding to the lab after the project.

author: marshallh
author_rank: Unknown
timestamp: August 12, 2013, 03:19:49 am
content: YOu're overthinking it, just start building stuff. That is the important part.Everything else will come after that.You seem to have a vague idea of what you want, that's good. Once you start working towards that goal you'll be able to see it more clearly, or more likely change the goal.

author: Krinkleneck
author_rank: Contributor
timestamp: August 12, 2013, 03:45:48 am
content: I may not be officially starting to work on it right now, but I have been mentally contemplating it for a year or two. I don't have a very vague notion of what I want, but there are vague parts on how I will get there. Before I get out of simulation and brainstorming I want to have the correct equipment for this job and future jobs. I have worked with knockoffs long enough to know how much more work you have to put in. Also I can't start building until my I get approval and funding to complete the design. Even though this printer is among the most useful tools I can make, it has left me strapped for cash... I wonder if I put this in the right board. I was kind of hoping for more opinions on equipment, and suggestions for any possible equipment that I was missing. I guess I compiled a good list.TLDR:Thanks for the advice, and I am pursuing the goal.

author: free_electron
author_rank: Super Contributor
timestamp: August 12, 2013, 07:29:52 am
content: Quote from: Krinkleneck on August 12, 2013, 02:40:56 amWho's talking usb scopes ? i said a good 4 channel scope, preferrably a mixed signal one like the agilent 3000 or 4000 series. if you get the AWG option you can eliminate the signal generator from your list. that scope can grow. even if budget is limited now you can tack on features later as opposed to having to buy a complete new scope.if you can't afford mixed mode , go for a 4 channel machine and get a salae usb grabber for logic sampling. DO NOT COMPROMISE ON 2 or 4 CHANNELS ! 4 channels is the way to go.2) even for repair you always need a part you don't have. i've done enough repairs... i never use recycled parts or substitutes. it's gotta be the real deal.3) time to go hunting for a rework station...

author: Mechatrommer
author_rank: Super Contributor
timestamp: August 12, 2013, 08:47:55 am
content: having 2 multimeters is sensible idea (a) as mentioned volt & current probing (b) to tally each other for more confidence. 2 or 3 psu? cant it be 1 psu with dual output? but if you can afford it, why not? afaik newbies proposing list of equipments in this forum, this is the most sensible one, what i like most is the provision of lots of smd and through hole components. but what i dont like is... why the need of both digital and analog scope? i know there are advantages to analog scope, but... move on, we seldomly need analog scope anymore unless you are thinking to become Bob Pease or Jim William. USB scope or usb FG? no no! unless you are on tight ass budget. struggle for standalone dso first and then if you really tight, get usb fg. dso will be your mostly used item, so connecting to PC everytime can be annoying.

author: Sigmoid
author_rank: Frequent Contributor
timestamp: August 12, 2013, 02:21:45 pm
content: Quote from: Mechatrommer on August 12, 2013, 08:47:55 amDunno, from what I've seen, the digital scopes that truly replace an analog in repetitive signals are continuous acquisition DPOs, and cost a month's salary. For someone working on Wall Street, that is.Add to that the fact that you can have a truly awesome analog for less than $300, and a passable one for $50...

author: Krinkleneck
author_rank: Contributor
timestamp: August 13, 2013, 05:15:41 am
content: Quote from: Mechatrommer on August 12, 2013, 08:47:55 amI appreciate the approval and thought behind this post. I just wanted to say a couple more things. Firstly I wasn't even looking a PC based oscilloscope, and the analog scope would be my +1 scope in the lab that is accurate and cheap. That way I can pay for one stellar DSO, and have an awesome Analog backup without paying double the price.

author: sonnytiger
author_rank: Frequent Contributor
timestamp: August 13, 2013, 02:38:07 pm
content: You seem to have your mind pretty much set, why are you even asking people for their opinion?

author: Krinkleneck
author_rank: Contributor
timestamp: October 08, 2013, 12:26:16 am
content: Check opinions... sorry for bumping, but I don't like leaving things hanging when I remember to access the forum