I am looking to invest in some test lab equipment to enable accurate testing of circuits I build or modify. Ultimately I would like to be in a position a year from now to be able to diagnose audio amplifiers, tube and solid state and fix them.
Admittedly apart from college I have no electronic testing experience other than validation of test reports frequency plots etc.
So to summarise:
1.) If you could advise on educational resources that I could learn the theory from.
2.) Starting with an initial budget of say £2k, equipment that you would invest in and why.
3.) Initially I want to do this as a hobby but ultimately as a evening job diagnosing/ fixing audio equipment- in today's climate specifically in the UK is there much scope for this (no pun intended), or are the margins that small it's not viable as anything other than a hobby?
Your thoughts, feedback, advice, guidance are welcome.
Thanks
Paul
Admittedly apart from college I have no electronic testing experience other than validation of test reports frequency plots etc.
So to summarise:
1.) If you could advise on educational resources that I could learn the theory from.
2.) Starting with an initial budget of say £2k, equipment that you would invest in and why.
3.) Initially I want to do this as a hobby but ultimately as a evening job diagnosing/ fixing audio equipment- in today's climate specifically in the UK is there much scope for this (no pun intended), or are the margins that small it's not viable as anything other than a hobby?
Your thoughts, feedback, advice, guidance are welcome.
Thanks
Paul
What you would need would be a bench power supply, a scope and an audio analyzer solution. Lots of cables and adapters will accumulate despite your best efforts. I think the QA403 is the best value for audio measurements. for scopes a Rigol or Siglent is a good investment. I'm partial to vintage Lambda power supplies but there are many options.
We would need more insight into your current knowledge of basic electronics before making meanngful suggestions for educational resources.
We would need more insight into your current knowledge of basic electronics before making meanngful suggestions for educational resources.
Thank you for your reply and help.
I did a college course in electronics back in 1998, very little practical due the local political environment.
In 2000 did an aero degree with Avionics modules, again very little practical.
In 2004 I was fixing aircraft, small amount of electrical work, then automated testing of radar systems.
In more recent years, I had to pass IPC courses 610&620.
Performed continuity testing on complex electronic boards merged with mechanical assemblies from 5v logic boards to 60kv power circuits.
The majority of work was reviewing production and how to consolidate our current testing, and reviewing test results before they went to international customers. We had a dedicated test team that used equipment that expensive it was supplied under license by the DOD.
Aside from that worked in a contract manufacturer of PCBs but it was completely hands off.
In terms of theory I understand nothing currently, I understand what components are and their uses.
I couldn't tell you any formulas but I will look them up and automate calculations in spreadsheets.
I'm just currently going through repair videos to learn diagnostic work flow on different items.
I'm usually very methodical in work because I have to be to find rca and quick resolution for production. And inspection of boards to feed production.
Any guidance on free software for circuit design would be useful to simulate designs and operation if possible.
I regret not learning more from our professional test team however access was limited for high voltage reasons.
I did a college course in electronics back in 1998, very little practical due the local political environment.
In 2000 did an aero degree with Avionics modules, again very little practical.
In 2004 I was fixing aircraft, small amount of electrical work, then automated testing of radar systems.
In more recent years, I had to pass IPC courses 610&620.
Performed continuity testing on complex electronic boards merged with mechanical assemblies from 5v logic boards to 60kv power circuits.
The majority of work was reviewing production and how to consolidate our current testing, and reviewing test results before they went to international customers. We had a dedicated test team that used equipment that expensive it was supplied under license by the DOD.
Aside from that worked in a contract manufacturer of PCBs but it was completely hands off.
In terms of theory I understand nothing currently, I understand what components are and their uses.
I couldn't tell you any formulas but I will look them up and automate calculations in spreadsheets.
I'm just currently going through repair videos to learn diagnostic work flow on different items.
I'm usually very methodical in work because I have to be to find rca and quick resolution for production. And inspection of boards to feed production.
Any guidance on free software for circuit design would be useful to simulate designs and operation if possible.
I regret not learning more from our professional test team however access was limited for high voltage reasons.
I would get The Art of Electronics book, by far the best single source to learn electronics.
Second edition (used) if you just want the basics.
Third edition (current) if you want to go farther.
Second edition (used) if you just want the basics.
Third edition (current) if you want to go farther.
There are many copies of each used.
Third edition is also available new as either a physical or ebook.
Third edition is also available new as either a physical or ebook.
A really great professor of mine once told us that if we read and understood The Feynman Lectures on Physics, we'd have 95% of the world understood. Not the details on some new stuff, of course, but the vast portion of the real fundamentals. So, I went to the college book store, put down my $35 (a lot in those days) and set to reading. I still have the books. But, now you can read it all for free:
The Feynman Lectures on Physics
The Art of Electronics is similar, but for electronics. Not free, but as others have said, you can get used editions for a reasonable price. I still refer to Horowitz and Hill routinely.
The Art of Electronics
As for test gear, you can put together a great lab for $2000 or equivalent Euros. Yeah, you won't have the fancy icons in the screen shots that the very expensive professional test gear provides, but if you aren't performing professional testing and analysis that doesn't matter much. With some understanding, you can get pretty much the same quality of measurements. Certainly good enough for repairing and even developing audio equipment.
Just as a reference, not intended to be a recommendation, I have about $2000 invested in the following:
Audio DAC for source
Audio ADC for measurement
Scaler for use with ADC
Notch filter for use with ADC
Digital multimeter
Multipurpose scope (Analog Discovery 2)
Transistor tester and curve tracer
RF spectrum analyzer
RF Vector Network Analyser
That comes to about $2k, all new pricing. There's also a bunch of those cables, probes, dummy loads, and so on that add to that. Plus, some power supplies - mostly wall warts and batteries for me. There's also some gear that I don't use much any longer, because it's been effectively replaced with the above.
With the above, I was even able to do lab work for my day job during the time when we were all told to stay home due to the pandemic. The big thing was knowing what the testing needed to be and understanding the limits of the test gear at hand, and how to get around some of the limitations. At least one patent came from that effort. (Nothing to do with audio.)
Two key aspects that are and were important, at least to me. I don't have a dedicated room just for a lab. So, I wanted to minimize the space taken. A lot of test gear often gets used intensely for a few days or weeks and then sits on the shelf for months after anyway. So, I focused on test gear that was small and by its nature worked through a computer. My whole "lab" sits on a single closet shelf when not in use. It gets dragged out when it's needed.
Computer based test gear isn't ideal for all jobs - the digital multimeter is a good example. It's far easier to just plug in the test probes and measure. No chance for funny ground loops causing safety problems or measurement error. The same would probably be true for a scope, if that's something you'd use a lot, like for repairs. But, computer based test gear does have a lot of advantages like large screens, the easy ability to save the results and analyze those results, and so on. Plus, obviously, you already own a computer.
Understanding the problem you want solve is the most important beginning.
The Feynman Lectures on Physics
The Art of Electronics is similar, but for electronics. Not free, but as others have said, you can get used editions for a reasonable price. I still refer to Horowitz and Hill routinely.
The Art of Electronics
As for test gear, you can put together a great lab for $2000 or equivalent Euros. Yeah, you won't have the fancy icons in the screen shots that the very expensive professional test gear provides, but if you aren't performing professional testing and analysis that doesn't matter much. With some understanding, you can get pretty much the same quality of measurements. Certainly good enough for repairing and even developing audio equipment.
Just as a reference, not intended to be a recommendation, I have about $2000 invested in the following:
Audio DAC for source
Audio ADC for measurement
Scaler for use with ADC
Notch filter for use with ADC
Digital multimeter
Multipurpose scope (Analog Discovery 2)
Transistor tester and curve tracer
RF spectrum analyzer
RF Vector Network Analyser
That comes to about $2k, all new pricing. There's also a bunch of those cables, probes, dummy loads, and so on that add to that. Plus, some power supplies - mostly wall warts and batteries for me. There's also some gear that I don't use much any longer, because it's been effectively replaced with the above.
With the above, I was even able to do lab work for my day job during the time when we were all told to stay home due to the pandemic. The big thing was knowing what the testing needed to be and understanding the limits of the test gear at hand, and how to get around some of the limitations. At least one patent came from that effort. (Nothing to do with audio.)
Two key aspects that are and were important, at least to me. I don't have a dedicated room just for a lab. So, I wanted to minimize the space taken. A lot of test gear often gets used intensely for a few days or weeks and then sits on the shelf for months after anyway. So, I focused on test gear that was small and by its nature worked through a computer. My whole "lab" sits on a single closet shelf when not in use. It gets dragged out when it's needed.
Computer based test gear isn't ideal for all jobs - the digital multimeter is a good example. It's far easier to just plug in the test probes and measure. No chance for funny ground loops causing safety problems or measurement error. The same would probably be true for a scope, if that's something you'd use a lot, like for repairs. But, computer based test gear does have a lot of advantages like large screens, the easy ability to save the results and analyze those results, and so on. Plus, obviously, you already own a computer.
Understanding the problem you want solve is the most important beginning.
While not a budget buster, cables add more than you might expect if you need BNC for say the signal generator. I've not found an inexpensive source for BNC, maybe someone else has. I do recall in college I worked in a lab, and during slack time we'd make our own BNC's to save a few bucks. Even the connectors back then were a couple bucks each if I remember right. I picked up a 2' and 3' from digi a few months ago and I think they were around 10 ea.
For audio these are perfecty fine: https://www.amazon.com/gp/product/B00B887VIM/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1 and $8 ea. I chop them and terminate into the connectors I need. And these seem to be of pretty good quality: https://www.amazon.com/dp/B06XX25HFX?ref=ppx_yo2ov_dt_b_product_details&th=1 The ones I tested were all under 100 milliOhms including clips at each end.
Thank you, I will definitely get some of these ordered when I'm back in the West.
Found a box of electronic equipment in the office at home and it's full of wee boards for hooking into control boards for diagnostics and a logic testing unit. Buying electronic equipment were I am is extortionate, approximately £250 for a multimeter, £1500 for a scope, think I will buy back in the UK.
Do you keep many BNC cables spare or do they last pretty well?
Found a box of electronic equipment in the office at home and it's full of wee boards for hooking into control boards for diagnostics and a logic testing unit. Buying electronic equipment were I am is extortionate, approximately £250 for a multimeter, £1500 for a scope, think I will buy back in the UK.
Do you keep many BNC cables spare or do they last pretty well?
Depending on what you get, you may not need any BNC. You mentioned a signal gen, and the rigol's, etc will have a BNC for output that for audio will need to get converted to something else. Audio rarely uses BNC for anything, just not needed for the bandwidths in audio. I use a audio interface for signal gen (a scarlett) and so up until recently I did not have any BNC's. Scope's I use the supplied probes, which are also pricey if you need to replace one. I needed a BNC because I got a second scope and wanted to look at 6 channels simultaneously, so needed a BNC to connect the trig out of the 1st scope to the external trig in of the second. And when I went to order one was kind of shocked that the prices had not come down on them like everything else from the east.
Thanks for your help Mike, today the news does not look too hot so thinking i will have to take a completely different approach and at a later stage go into refurbishing radios and audio equipment.
I might have to prioritise portability for travelling and i might have to go into repairing laptops/computers instead.
Yeah we used to use BNCs loads at work but that was Ghz (The product was, not sure what the range on the scopes were), all i know is the test equipment was so expensive it was supplied to the UK by the US, we then setup a factory in the US and got bought out in the end.
I might have to prioritise portability for travelling and i might have to go into repairing laptops/computers instead.
Yeah we used to use BNCs loads at work but that was Ghz (The product was, not sure what the range on the scopes were), all i know is the test equipment was so expensive it was supplied to the UK by the US, we then setup a factory in the US and got bought out in the end.
@1audio Would bnc terminated rg59 be acceptable for scope use? As a new scope user, this thread caught my eye just as I happen to be replacing an analog surveillance system and a couple dozen cables are headed for the dumpster today.
@Notascoobynewbie my apologies. I don't mean to hijack your thread.
@Notascoobynewbie my apologies. I don't mean to hijack your thread.
BNC cables- First for signals above 500 KHz or so cable impedance matters. Second fatter cables lose less of the RF usually. But a BNC cable is different from a scope probe. Scope probes are desinged to reduce the signal level have minimum impact on the signals to be measured. The internal cables are ususlly resistance wire that is tuned with the resistor in the probe tip and the shunt capacitance in the probe tip. So no easy answer to the utility of the cables. It depends on what you will be measuring.
Thankyou for all your replies, everyone has been very helpful and friendly.
@1audio & Mike ATX-Had a look locally and most BNCs are 50cm/50Ohm for £2, Others are 1m long for £6, but the decent ones i can find are approx £20 a piece.
@CG-I will have a dedicated Test Room and another storage Room, In the process of building a reinforced concrete basement-seriously considering putting the sound system in there so i can crank it up without the neighbours going ballistic. I like the idea of equipment being portable i can throw it in the case with the laptop and then don't need to pay import taxes.
That said i agree i need to think more about what i want to achieve to narrow down what i should invest in specifically.
Without seeming nosy do you mind if i ask for recommendations for the equipment below, with the exceptions of multi meter
Audio DAC for source
Audio ADC for measurement
Scaler for use with ADC
Notch filter for use with ADC
Digital multimeter
Multipurpose scope (Analog Discovery 2) Approx £700 here. Hantek is more affordable but now multipurpose.
Transistor tester and curve tracer
RF spectrum analyzer-I assume you dont mean this badboy?
RF Vector Network Analyser
@1audio & Mike ATX-Had a look locally and most BNCs are 50cm/50Ohm for £2, Others are 1m long for £6, but the decent ones i can find are approx £20 a piece.
@CG-I will have a dedicated Test Room and another storage Room, In the process of building a reinforced concrete basement-seriously considering putting the sound system in there so i can crank it up without the neighbours going ballistic. I like the idea of equipment being portable i can throw it in the case with the laptop and then don't need to pay import taxes.
That said i agree i need to think more about what i want to achieve to narrow down what i should invest in specifically.
Without seeming nosy do you mind if i ask for recommendations for the equipment below, with the exceptions of multi meter
Audio DAC for source
Audio ADC for measurement
Scaler for use with ADC
Notch filter for use with ADC
Digital multimeter
Multipurpose scope (Analog Discovery 2) Approx £700 here. Hantek is more affordable but now multipurpose.
Transistor tester and curve tracer
RF spectrum analyzer-I assume you dont mean this badboy?
RF Vector Network Analyser
Before I retired, I spent a lot of time in various labs. I got really tired of seeing test gear get dusty (cleaning is no fun) and the sound of fans roaring away. It might be impressive to look at and is certainly necessary for certain commercial activities, but I don't care about that.
So, here's what I am using now. Some of this might change over time as newer better stuff comes along.
Audio DAC for source - Topping E50
Audio ADC for measurement - Cosmos ADCiso
Scaler for use with ADC - Cosmos Scaler
Notch filter for use with ADC - Cosmos APU
Digital multimeter - Fluke 87 (30+ years old and still going strong)
Multipurpose scope - Analog Discovery 2
Transistor tester and curve tracer - Peak Atlas DCA-75
RF spectrum analyzer - tinySA
RF Vector Network Analyser - NanoVNA
I also own a QA401, but they're no longer made. The replacement wasn't available when I bought the Cosmos stuff, but I'm sure it's fine and it is integrated into a single unit.
For software, I use Room Equalization Wizard and Multitone. Plus the software that came with the hardware, of course.
My list would not and should not be the same as yours. It depends on where you are located and what you're trying to do.
Once again, I do this for fun. No money ever changes hands toward my direction. So, I am willing to spend the extra time to do things in a way that works for me. If I was charging for repair services, I'd veer toward a stand alone oscilloscope because it's really fast to use. I'd probably also choose a QA403 over the Cosmos stuff. It isn't quite as good with regard to ultimate distortion capabilities, but so what? If you're fixing stuff, that's different than developing stuff and tinkering for intellectual curiosity. The QA403 is more plug'n'play. Similarly, you wouldn't really need a notch filter either for the same reasons. But, I'm not going to go into the repair business and have not ever been in the repair business, so those opinions are just guesses from outside that world.
You almost certainly would not need a VNA for service activities. A small spectrum analyzer would probably be helpful for finding high frequency instabilities and oscillations that normal audio gear wouldn't directly pick up on. A proper scope would, though.
Here's a funny thing...
I know a bunch of guys who are test gear fetishists. It's a part of their collection of hobbies. Good for them, but not for me.
I also know a bunch of guys who buy gear like what I mentioned. It doesn't cost a lot and when a new gadget comes along that really is better in some useful way, they buy the new kit. But, the problem is - what to do with the piece the new kit is replacing? NOBODY WANTS IT! It's hard to give it away. Big puzzle for me.
So, here's what I am using now. Some of this might change over time as newer better stuff comes along.
Audio DAC for source - Topping E50
Audio ADC for measurement - Cosmos ADCiso
Scaler for use with ADC - Cosmos Scaler
Notch filter for use with ADC - Cosmos APU
Digital multimeter - Fluke 87 (30+ years old and still going strong)
Multipurpose scope - Analog Discovery 2
Transistor tester and curve tracer - Peak Atlas DCA-75
RF spectrum analyzer - tinySA
RF Vector Network Analyser - NanoVNA
I also own a QA401, but they're no longer made. The replacement wasn't available when I bought the Cosmos stuff, but I'm sure it's fine and it is integrated into a single unit.
For software, I use Room Equalization Wizard and Multitone. Plus the software that came with the hardware, of course.
My list would not and should not be the same as yours. It depends on where you are located and what you're trying to do.
Once again, I do this for fun. No money ever changes hands toward my direction. So, I am willing to spend the extra time to do things in a way that works for me. If I was charging for repair services, I'd veer toward a stand alone oscilloscope because it's really fast to use. I'd probably also choose a QA403 over the Cosmos stuff. It isn't quite as good with regard to ultimate distortion capabilities, but so what? If you're fixing stuff, that's different than developing stuff and tinkering for intellectual curiosity. The QA403 is more plug'n'play. Similarly, you wouldn't really need a notch filter either for the same reasons. But, I'm not going to go into the repair business and have not ever been in the repair business, so those opinions are just guesses from outside that world.
You almost certainly would not need a VNA for service activities. A small spectrum analyzer would probably be helpful for finding high frequency instabilities and oscillations that normal audio gear wouldn't directly pick up on. A proper scope would, though.
Here's a funny thing...
I know a bunch of guys who are test gear fetishists. It's a part of their collection of hobbies. Good for them, but not for me.
I also know a bunch of guys who buy gear like what I mentioned. It doesn't cost a lot and when a new gadget comes along that really is better in some useful way, they buy the new kit. But, the problem is - what to do with the piece the new kit is replacing? NOBODY WANTS IT! It's hard to give it away. Big puzzle for me.
Genuinely appreciated CG.
That's a brilliant starting point for me. To be very honest i wont purchase something if it hasn't got a use or function i require.
In the UK it would just be a hobby on top of ordinary work, but where i am i will setup after i have enough experience to make some cash, at 40 i took a 2 year break and I'm at the point now where if i don't get back to work i will lose my mind from boredom.
Our Electronics director was 70, fit as a fiddle and he could run rings around the young engineers but he had a brilliant sense of humour. He would joke who employed these jokers, what do they get taught in university if they cant do simple calculations using a scope. I used to laugh as we had big DOD projects and i used to question the director asking is their no conflict of interest given we know the in field use and we have a wee Iranian lady building the product. Unsurprisingly it will likely be manufactured in the states before long.
Is their not an equivalent of camera shops selling old cameras with Test equipment? where its quality assured before selling onto a willing candidate.
That's a brilliant starting point for me. To be very honest i wont purchase something if it hasn't got a use or function i require.
In the UK it would just be a hobby on top of ordinary work, but where i am i will setup after i have enough experience to make some cash, at 40 i took a 2 year break and I'm at the point now where if i don't get back to work i will lose my mind from boredom.
Our Electronics director was 70, fit as a fiddle and he could run rings around the young engineers but he had a brilliant sense of humour. He would joke who employed these jokers, what do they get taught in university if they cant do simple calculations using a scope. I used to laugh as we had big DOD projects and i used to question the director asking is their no conflict of interest given we know the in field use and we have a wee Iranian lady building the product. Unsurprisingly it will likely be manufactured in the states before long.
Is their not an equivalent of camera shops selling old cameras with Test equipment? where its quality assured before selling onto a willing candidate.
"Is their not an equivalent of camera shops selling old cameras with Test equipment? where its quality assured before selling onto a willing candidate."
If there is, I haven't found it. There are used test equipment emporiums, but usually they are associated with equipment rental/lease companies. (That's a preferred way to acquire test equipment for a lot of companies here. There's often tax advantages, plus you get new gear with shiny new front panels when the lease period is up.) Most of these places aren't especially keen on onesy lots of test gear. Besides, it's easier and more appealing for many to buy "surplus" test gear on eBay. I'd love to be proven wrong here.
Now that I think of it, this is largely true for audio gear, too. The organized used market isn't so great here. There are a few exceptions, and several of the shops still operating will take used gear in trade for new gear, but generally it's a dog eat dog world. I know several guys - all guys, as it happens - who have lots of slightly used audio gear taking up space in the garage or basement (one guy had a shed built for his unused used gear). They've found that's there's less pain associated with storing the gear until they die or a flood comes by than in dealing with audiophile shoppers. They'd sell the gear for a modest price or give it to a worthy cause, but they also don't want to read a classified ad a couple weeks later with the gear being resold at twice what they sold it for with a dubious story attached. Nobody really likes being played as a sucker.
BTW, those classic camera shops are kind of few and far between here as well now. There's the big guys in NYC and a few other cities who really are genuinely honest and good. There's some boutique places as well. But, I live in one of the more affluent states of the USA and there aren't too many here that I know of.
If there is, I haven't found it. There are used test equipment emporiums, but usually they are associated with equipment rental/lease companies. (That's a preferred way to acquire test equipment for a lot of companies here. There's often tax advantages, plus you get new gear with shiny new front panels when the lease period is up.) Most of these places aren't especially keen on onesy lots of test gear. Besides, it's easier and more appealing for many to buy "surplus" test gear on eBay. I'd love to be proven wrong here.
Now that I think of it, this is largely true for audio gear, too. The organized used market isn't so great here. There are a few exceptions, and several of the shops still operating will take used gear in trade for new gear, but generally it's a dog eat dog world. I know several guys - all guys, as it happens - who have lots of slightly used audio gear taking up space in the garage or basement (one guy had a shed built for his unused used gear). They've found that's there's less pain associated with storing the gear until they die or a flood comes by than in dealing with audiophile shoppers. They'd sell the gear for a modest price or give it to a worthy cause, but they also don't want to read a classified ad a couple weeks later with the gear being resold at twice what they sold it for with a dubious story attached. Nobody really likes being played as a sucker.
BTW, those classic camera shops are kind of few and far between here as well now. There's the big guys in NYC and a few other cities who really are genuinely honest and good. There's some boutique places as well. But, I live in one of the more affluent states of the USA and there aren't too many here that I know of.
I can't really vouch for accuracy if you have higher standards than me - which you probably do - but £2k sounds like a bit more than you might need to spend, unless you're insistent on new equipment. An old analogue oscilloscope doesn't have to be expensive, I would have paid the equivalent of about 40 or 50 £ for mine. I also use an audio signal generator, and an AC millivolt meter. This stuff is all Leader, Kikusui, or similar Jpn makers. My multimeter is an autoranging China special from Amazon, perfectly adequate for me, cost about £20, it's bristling with features, and I will confess that I love it. Some of the electronic blogs mention the China brands they like. I believe mine is AstroAI.
What I'm saying is I think I might have spent no more than about £130 on some basic test tools, and for starting out, that might work for you. You can always replace them with pricier items later.
What I'm saying is I think I might have spent no more than about £130 on some basic test tools, and for starting out, that might work for you. You can always replace them with pricier items later.
I think a good used HP dual power supply like a 6227B will help since you can test solid state amplifier modules with current limits and under ideal conditions even before dim bulb testing. These are military grade items with gold plated pcbs and no expense spared in construction but may need a little TLC to perform perfectly. A decent used 100 or 200 MHZ tektronix 80s or early 90s scope can be had for about $250-300 usd. A decent USB sound card for use with rew can be had for a hundred or so. I do hardware for a living and do yourself a favor and do not head the siren call of cheap digital multimeters. Pay the $200 and get a decent fluke or you best choice. Nothing is more frustrating than a flakey meter! You also want to trust your meter to do zero voltage verifications that your life may rely on. A variac is nice and a nice soldering/desoldering station will get you far. The advice from CG is spot on.