How do you quickly check that you have all components of your BOM? - Page 1
Forum section: electronics / beginners

author: electricar
author_rank: Regular Contributor
timestamp: April 21, 2016, 08:30:14 am
content: Hi folks,my component stock grew lately and I wanted to ask you about your method to check if you have the components in stock when looking at the BOM of your new project?Do you have a library in your schematic/layout software with all your components listed up with an own partnumber?Off course you could go through your spreadsheet (if you have one) and look up every component separately, but that would be horrible with huge BOMs.I think it would save a lot of time if the BOM could automatically been compared to your stocked components.RegardsElectricar

author: MrSlack
author_rank: Frequent Contributor
timestamp: April 21, 2016, 08:45:39 am
content: I do the inverse. I build the BOM and device based on what I have on hand.

author: tszaboo
author_rank: Super Contributor
timestamp: April 21, 2016, 09:09:53 am
content: You use an ERP like SAP to do that. If not, than you write a Goods request to the logistics department, and get two signatures on a requisition form. And then an Inbound delivery goods received form when they arrive.No, jokes aside, if you are concerned about stock and such, than you either use something professional, or spend hours checking if something you have or not. It is always a lot of time, because exceptions. And you either spend a lot of time updating the stock or spend a lot of time searching for it.If the BOM is not that expensive, and you only make half a dozen of your thing, the best I've found is to order the exact amount + 1 that you need, and trash the remaining parts (well, put it into a box with a label and forget about it). Fastest solution by far. And time is money.

author: jitter
author_rank: Frequent Contributor
timestamp: April 21, 2016, 05:09:53 pm
content: Yuk, SAP, it's not really an intuitive programme. The company I work for uses SAP, but has built its own tool that searches all available components across all plants.But basically, yeah, you must build a database in which you can search on certain parameters. Easy when it comes to components that are unique, a bit harder when it comes to stuff like resistors with all their different shapes, sizes, values, TCs, tolerances, etc.

author: suicidaleggroll
author_rank: Super Contributor
timestamp: April 21, 2016, 05:23:32 pm
content: Quote from: NANDBlog on April 21, 2016, 09:09:53 amThat's what I do on small projects. Just order a few extra in case you need them and throw all leftovers in a labeled box/bag. On the rare occasion a new project needs 1-2 extra parts that you know you've used in another project, you can dig out that project's bag and you should have a couple spare sitting there, otherwise you just order what you need for each project.

author: rstofer
author_rank: Super Contributor
timestamp: April 21, 2016, 06:32:04 pm
content: I'm in the 'buy it all' camp. I have a LOT of components laying around and I created a database one time but it is just too difficult to keep up to date. Besides, keywords are usually something I come up with at the moment and I didn't want to create a key word search or add tags to the description. Motor driver vs H-Bridge, that kind of thing. I just never wanted to be a database administrator or programmer.It's just easier to get all the components in the same box from DigiKey.

author: Jeroen3
author_rank: Super Contributor
timestamp: April 21, 2016, 07:24:50 pm
content: Three options:1. Use some overpriced BOM management software or service. The free versions of inventory software never have "project" capabilities.2. Buy all the stuff in a box per bag labeled from Farnell/Digikey.3. Waste a day looking for all the parts.It's option 2 for me.Advantages:- You have no stock to waste time on or to lose.- You will know when parts become obsolete before the assembly house tells you.Disadvantages:- You'll pay a accumulated fortune of cut-tape costs to Farnell and DigiKey. (but high volume buyers eventually get discounts)

author: electricar
author_rank: Regular Contributor
timestamp: April 22, 2016, 06:45:23 am
content: I'm quite impressed how your method of putting all those components in a big box works for you for years now!Quote from: MrSlack on April 21, 2016, 08:45:39 amBut how do you know what parts you have?Quote from: NANDBlog on April 21, 2016, 09:09:53 amI can imagine that this method is quite fast, but what about resistors and capacitors? Do you order every time the "same" resistors, capacitors, ICs although you know or don't know you have exactly this value lying around? That is the point I'm talking about.I began with my own excel/vba sheet with auto-filters, wildcard search, userform for adding new parts, possibilty to enter your own parameters to each type of component (eg. Qg for FETs) etc. I'm still at the beginning and you could off course add a lot of more functions and make it look more professional. (I'm an electronics hardware developer, not a software developer)I think in the beginning you have to spend a little more time to get started entering every component to the spreadsheet, but it will save you lots of time in the future because you now exactly which parts you have, where there are located etc. Also you can filter on many parameters.

author: Kjelt
author_rank: Super Contributor
timestamp: April 22, 2016, 07:16:43 am
content: You sent the BOM of your product to the Purchase and Order dept. they take care of itFor my own stuff I have an excel sheet where all parts, the amount of parts and locations and datasheet names are listed.All passives are on stock (tapereel) all expensive parts are bought in front of ordering the pcb, I want to have them on my desk before I order a single PCB, I once was burned that I could not get hold of an part I designed in, or had to buy 1000 pcs or something like that at $4 a piece. So I had to redesign the whole stuff, never gonna happen again.Also for rare parts don't trust the internet, some companies that listed having 40 pieces in stock failed to find those 40 pieces and left me in the cold, bad to design in something rare in the first place but this was non-commercial just hobby.But hey probably you have to be burned yourself once in order to change your way of working.

author: MrSlack
author_rank: Frequent Contributor
timestamp: April 22, 2016, 10:38:18 am
content: Quote from: electricar on April 22, 2016, 06:45:23 amI have no idea what specific parts I have in stock as they are grouped by specification, not by part number. Building an oscillator? Need a JFET. Open the box, pick a JFET. Use it. Building an RF amplifier? Open the box, grab something from the RF AMP NPN hole that looks big enough. Need an opamp single rail for around 10khz, grab one from the IC box in the (single rail <100khz column). Done. All relatively common interchangeable jellybean parts is the key.JFET was a Fairchild J113 and the RF amp was an SGS 2n2222a and the opamp was an LM358. Write that one schematic when it's working.I've come unstuck perhaps 1-2 times in the last 25 years and had to order something. Most of them used to be extracted from dead kit, tested and filed but I have just bought NOS stuff in the last 10 years or so and thrown all the pulls out.

author: Kilrah
author_rank: Unknown
timestamp: April 22, 2016, 12:42:16 pm
content: Quote from: electricar on April 22, 2016, 06:45:23 amYup, personally for passives I tend to try and always order the same series I know well as long as there isn't a specific requirement, so that eventually the couple of spares of each project could be put together at some point.So yeah, I order by project even stuff I might already have. Then either keep a bag per project I could go back to, or put in a box grouped with "reasonably similar" spec parts in order not to be mucking around with too many references. I never dig much into the stock beyond quick prototyping and would typically have a rough idea in mind of what I have, no database.

author: suicidaleggroll
author_rank: Super Contributor
timestamp: April 22, 2016, 01:16:34 pm
content: Quote from: electricar on April 22, 2016, 06:45:23 amAbsolutely. It goes back to the old saying, time is money. I know it's cliche, but it can help to put things in perspective.How much is your free time worth to you? Just think to yourself, if you knew that you could go out and get a job working in your spare time, how much would that job have to pay you for it to be worth it? If you don't currently have a job, probably pretty little. If you have a high paying job and are always strapped for time, probably a lot. Everyone is different, there's no wrong answer. Another way to look at it is if your current job offered you overtime, would you take it, and with what incentives? Normal pay, half pay, time and a half, double time? What would it take for it to be worth it to you? Or if you saw a penny lying in the street, would you pick it up? Studies/experiments have been done that show most people don't, the few seconds it would take to go out of their way to pick it up is worth more to them than the penny. How about a nickel, dime, quarter, or dollar?Let's say you come up with a number of $20/hr. If somebody offered you a job you didn't really like but didn't absolutely hate and you could do it in your spare time for $21/hr you'd take it, $19/hr you wouldn't. $20/hr comes out to $.0056/second. SMD resistors cost about $.01 in small quantities, so about 2 seconds worth of your time. If you need 10 resistors for your project and it takes you more than 20 seconds longer to look them up in your database, modify quantities, find them in your stock, etc. versus buying a new batch of 10 from digikey, then it's a waste of time and you're better off just buying new whenever you need them and tossing the leftovers. With something as cheap as passives, it doesn't make sense to keep and maintain and inventory management system. For more expensive parts it might, depends on what you're doing.

author: electricar
author_rank: Regular Contributor
timestamp: April 24, 2016, 12:47:02 am
content: Quote from: Kjelt on April 22, 2016, 07:16:43 amMy approach is very similar. An excel sheet for the location, quantity and parameters of the parts.My SMD resistors (E12) and capacitors are stored in those enclosures (grey), the active devices are in the ESD type (black):http://www.ebay.com/itm/AideTek-involucro-SMD-organizzatore-BOX-ESD-Safe-IC-diodi-transistor-144-scomp-/281974482735?hash=item41a6fd272f:g:PD4AAOSwr7ZW76F1The bigger SMD devices and THT are put all together in boxes separated by types (FET, BJT, diode...)

author: jeroen79
author_rank: Frequent Contributor
timestamp: April 24, 2016, 07:27:21 am
content: If you keep a good digital inventory of the parts you own (database/spreadsheet) then it would be trivial to let it lookup and count an item on the bom in the inventory.You do need to be disciplined in naming things.

author: Brumby
author_rank: Unknown
timestamp: April 24, 2016, 01:27:54 pm
content: Quote from: jeroen79 on April 24, 2016, 07:27:21 amANDYou need to be disciplined in adding new stock as it comes inYou need to be disciplined in removing stock as it gets used, lost or damagedYou need to be disciplined in storing every item in its right place, so that you can find it when you want itYou also need to look after your database - maintenance, backup and integrity.My needs are small and I don't have much of an inventory of parts, but what I do have is basic - like an assortment of resistors, capacitors, a bag of 1N4004's and some other jellybean stuff. There's a few odd semi's and other things that have been pulled, but I've given up trying to harvest everything possible. Prices for new components these days just doesn't make it worthwhile.

author: Kjelt
author_rank: Super Contributor
timestamp: April 24, 2016, 02:31:03 pm
content: Actually that strategy is what a lot of production houses do, they order the stuff by the reel for the coming production run and ditch them when it is finished, sometimes throwing away hundreds of $ worth of components but still often cheaper then buying only a small strip and have that manually put back on a reel .The other reason they ditch the parts is the lifetime, you can only use them in a pro production environment for a limited amount of time due to oxydation and other factors.But as a hobbieist where you know you will be using some parts again and again (like your favorite microcontroller) it can be handy to buy a larger quantity and have them on stock, also if you need to repair some stuff or another small project comes in you can use the same pcb as prototype. I also order more pcb boards than needed because the extra price is negligable, so if I need 5 and the pcb house gives the same price for 20, I order 20. They often come in usefull when you least expect it and it is too handy too also have the right parts in stock.But then if you have an account with Farnell and you can order small quantities without shipping that is a nice thing to have.

author: SL4P
author_rank: Super Contributor
timestamp: April 24, 2016, 03:37:05 pm
content: It really helps from the start if you plan and manage your physical storage (shelves, cabinets, bins, cups etc)If you're ok putting all the NPN transistors in one bucket - weelll ok, but it may help if you partition them based on rating, variety, types, etc.Same for shelves - if you have a large enough area & lots of stock - then cups go in bins, bins go on shelves in order to collect specific categories together. If you only have 300 parts in total, then you'd be better off looking for them directly than developing a catalog system!For a small operation, you could write a spreadsheet with lookup macros for stock in-and-out, or a simple DB (SQL or Access) to do the same. SQL will scale better as you grow.Different solutions for different scale of requirement.

author: Laertes
author_rank: Regular Contributor
timestamp: April 24, 2016, 11:50:04 pm
content: I have previously used Partkeeprhttps://www.partkeepr.org/for this purpose. It might be a little excessive for single-user stocking, but if you share a lab among four people(as I did), it's worth it's weight in gold. Easy to set up, free, with project capabilities, filtering, storage locations, etc. etc. designed for small businesses and the like. It's just a bunch of PHP scripts and an SQL database, so you can easily modify it to fit your needs, if you are so inclined.To be honest, I only set this system up because while I looked for something to replace the excel sheets we used to keep track of our parts I was at an unrelated training at the company that developed Partkeepr(its a small EE company located in Augsburg, Germany) and saw their flyers.My verdict on it: For Open Source and free, it's the best inventory tracking system I have seen. Yeah, it requires discipline. But it works, and it works quite well. If you have an excel sheet with filters and VBA in the back, Partkeepr is probably the same/less effort for more featuresIt can be used as a full ERP suite(but only if you run a very small company/ your hobby shop wich for some obscure reason requires full ERP), but I have never used these parts, only the part keeping portions. We managed a database with about 100 "standard parts" like resistors and caps of different values/sizes and maybe another 75 more specific parts, ICs and the like, so a bit larger than many hobbyists might have. Also, again, these parts were used by four People instead of just one, so the managing effort necessary was higher that for the average hobbyist. For this purpose, it was a great tool.Do I recommend it above just keeping a bunch of excel sheets? If you have large BOMs on a regular basis(say, three dozen individual parts) - absolutely! If you work with multiple people - absolutely! But for a single hobbyist with small projects, I think the extra effort to set it up and maintain your parts database is not likely worth the effort. Nor, for that matter, are complicated excel sheets with VBA scripts, in my opinion. Just do what others here recommended - order exact quantities of your parts. For standard resistors and capacitors, take one all-purpose form factor(for me, its 0603 smd) that you can use on almost all your projects and order say 100 of each E12 or E24 value of these once. You can use them up for any project and just need to check occasionally when you use many of them how your stock levels are...

author: Felicitus
author_rank: Regular Contributor
timestamp: November 05, 2016, 05:22:43 pm
content: Quote from: Laertes on April 24, 2016, 11:50:04 pmActually the company behind PartKeepr doesn't offer training yet and we don't have flyers, and we are based in Mannheim, Germany. However, PartKeepr training in general sounds interesting, do you have a contact for me?