To scope or to logic analyzer? - Page 1
Forum section: electronics / testgear

author: netwinder
author_rank: Regular Contributor
timestamp: November 07, 2015, 07:19:16 pm
content: Hello EEVblog fourm!I'm not a beginner with electronics, however I don't know everything there is to know. If I do make any grammar mistakes, or terminology mistakes I do apologize.However my problem: I had an oscilloscope. I used to have a Tek 465, and it was running into problems that were correctable but eventually the high voltage multiplier failed on that, and I definitely am not in a position to attempt to repair it (as the high voltage multiplier cannot be taken apart, and i do not want to build one myself). The issue is i cannot afford a new oscilloscope, i'm only in high school. However, i do have other test equipment. I tried selling an older Hewlett-Packard 432A Power Meter on a local classifies site but that was to no avail. I'm not familiar with eBay, or how reliable of a seller i would be but now for the question:I dont want to part with this piece of test gear, sentimental value, however im willing to sell my HP 54620A (non colour version, likehttp://en.cxteng.com/UploadFiles/2015050815573612555.jpg). A few questions regarding it. It comes with the 16 channel probe, its in very good shape... Comes with the manual and the programming guide, i'm not sure if it has any fancy options other then a hp-ib interface. Specs for it are 16 channel, 500ms/s, not entirely sure about it's bandwidth but seehttp://www.keysight.com/en/pd-1000001435%3Aepsg%3Apro-pn-54620A/16-channel-logic-analyzer?cc=CA&lc=engfor more info.I'm curious if its worth selling, ive seen them go on ebay for 200 - 900, if i can get 200 for it thats a start to a new oscilloscope.. However is it worth trading something like that for a modern day oscilloscope? I don't intend to turn this into a "find a $50 oscilloscope on ebay" I'm in canada and its hard to find anything decent on Ebay.. Im just looking to see if its worth selling in exchange for a oscilloscope, and if it is worth it... How much to sell it for? and how to sell it?Thank you for your input!

author: Ian.M
author_rank: Super Contributor
timestamp: November 07, 2015, 07:37:28 pm
content: $200 CAD wont get you far towards a decent modern scope. It wont even get you a decent USB scope. IMHO the minimum for a serious general hobbyist is an analog 50MHz dual channel delay timebase scope or a 250Msample/s digital scope. If you are doing RF or fast logic, you'll need better. Music and audio guys, can get by with less. Also, unless you have a comparable or better logic analyser, or are going to swear off using LSI logic or MCUs, you'll have to figure in the replacement cost for that as well.

author: netwinder
author_rank: Regular Contributor
timestamp: November 07, 2015, 07:42:08 pm
content: That is very true, however i implied the $200 as a minimum range as id expect the logic analyzer to sell for... As it would be a start to a modern oscilloscope. Any idea how much it would *reasonably* be worth? Ive seen the model on Ebay from anywhere from $200 to $900, with the average working out to $500. However what would a reasonable offer be for it? if it is a good idea to sell it.

author: Ian.M
author_rank: Super Contributor
timestamp: November 07, 2015, 08:03:45 pm
content: A decent logic analyser doesn't come in much cheaper than a good quality entry level digital scope. Now you have two expensive items to replace and don't even have the money for one. How is that going to help you? You cant count on not getting a low final bid, and putting a high reserve on will cost you money. Not to mention the time to pack and ship + the risk of getting an a--ehole winning bidder returning it or disputing payment.IMHO, unless you have a pure analog university final year project on the go, so need a scope *NOW* because of the deadline, you are better off keeping the analyser and saving up for a scope. A month of Saturdays working hard doing odd-jobs and you'd be ahead on where you'd be if you sold it. Meanwhile, maybe a soundcard scope program (e.g.http://www.zeitnitz.eu/scope_en) would be good enough to get by while you are saving up.

author: netwinder
author_rank: Regular Contributor
timestamp: November 07, 2015, 08:07:48 pm
content: You are right... i'll keep searching Ebay i guess and hope to find something decent., thanks guys.

author: Electro Fan
author_rank: Super Contributor
timestamp: November 07, 2015, 09:00:15 pm
content: Quote from: netwinder on November 07, 2015, 07:42:08 pmYou are exploring very interesting territory. To help you get the most value for your investment it would be good to know more about your needs/plans/interests.Can you tell us more about what you want the a Logic Analyzer (and a scope) to do? Of course it's hard to say without first owning or using one, but are there particular projects you have in mind? What types of analog and digital signals from what types of devices do you plan to work with? How many channels? What speeds? What protocols? (serial? parallel?) What type of triggering do you anticipate needing? How long will the data sets be? What type of review ("rewind and view") features are you looking for? What is the total budget for analog scope and LA functionality that you have in mind?Another way of getting at your question(s): Is there anything the HP 54620A doesn't do that you need in a LA? If not, then it might be best to keep it (especially if it is in nice shape) and think about what you want in a scope. I think you will find that getting a MSO that meets or exceeds the capability of the HP 54620A on the LA side will probably be expensive. Therefore you are probably better off just adding the analog channel capability with an entry level DSO (the Rigol 1054Z is very popular here, of course). Alternatively, if you need newer/better/different LA functionality then you might want to look at a USB LA along with a scope such as the 1054Z.

author: netwinder
author_rank: Regular Contributor
timestamp: November 07, 2015, 09:40:42 pm
content: QuoteMy plans and interests? So far i'm a hobbyist with electronics and i plan on going to university for Electrical Engineering.. I have an understanding of basic analog and digital electronics, and i've been fairly avid about electronics for years now.QuoteI want the Logic analyzer to be able to debug and troubleshoot basic to more advanced logic circuits, I've done serial troubleshooting with the logic analyzer, 7 segment multiplexing troubleshooting, and general debugging with it. The oscilloscope I had (while it still worked) I used for basic amplifier circuts, I made a small bookshelf speaker amplifier and a small radio with it.. I also built a waveform generator out of a few op amps and some logic, and used the oscilloscope to troubleshoot it.I hope that gives you a general idea of the work i'm doing, i'm not re-inventing the circle or anything.QuoteIt does anything i want it to do, if i can keep it i definitely will.Overall though, if i can't afford to buy a new scope i guess i can buy a used one off of a local classifieds site or ebayI hope this answers your questionAn aside: I found this oscilloscope... And i can't believe what im seeing... Its a 3Ghz tektronix 11403A... It seems ridiculous but is it worth pursuing? Otherwise id look for a tek 2400 series or a Hp DSO, or anything equivalent.

author: Electro Fan
author_rank: Super Contributor
timestamp: November 07, 2015, 09:53:51 pm
content: Quote from: netwinder on November 07, 2015, 09:40:42 pmI think you are on a good path.If you are happy with the LA functionality of the HP 54620A and you are trying to keep your total budget below $400 or so I think you should keep the HP 54620A and look for the scope that best meets your needs. No sense in selling the HP 54620A and trying to reduplicate it's LA capabilities with another LA and/or a MSO. The HP 54620A seems to be a winner, so just focus on getting the best scope you can find for your budget.

author: netwinder
author_rank: Regular Contributor
timestamp: November 07, 2015, 10:39:59 pm
content: QuoteGood point, and thank you. I'm looking

author: tautech
author_rank: Super Contributor
timestamp: November 08, 2015, 07:08:07 am
content: Quote from: netwinder on November 07, 2015, 07:19:16 pmFix it.Follow this thread:https://www.eevblog.com/forum/repair/tektronix-465/