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Old 10th Oct 2017, 11:39 am   #21
Skywave
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Red face Re: The perils of homebrewing equipment

It must have been during 1990 when I retrieved a large HDD from a scrapped substantial & professional workstation. I can't recall its capacity now, but it was seriously substantial. In order to test it (fdisk, format, etc.) I hooked it up to a d.c. bench PSU. Who got their wiring colour-coding wrong and put +12v. on the +5v. rail?
Whoops!

Al.
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Old 10th Oct 2017, 11:53 am   #22
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Arrow Re: The perils of homebrewing equipment

Quote:
Originally Posted by Bazz4CQJ View Post
Skywave and myself had a terrible time last winter building endless published designs of RF Voltmeters, none of which worked to their claimed specs.
B
Ah yes! I'm glad you mentioned that. I gave up with published designs and went down the 'total D-I-Y route'. Long after I made my last post here on that subject, I persisted for many months with a design in attempts to obtain a performance that was satisfactory. Eventually, the demands on my available time to do non-hobby things had to take precedence, so further work on it had to stop. I've retained some of the various modules that comprise the overall project - and one day I might just return to try again.

It was only last night when I complied a list of non-hobby things that I need to do around this house: that list comprises about 23 tasks!

Al.
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Old 10th Oct 2017, 12:31 pm   #23
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Default Re: The perils of homebrewing equipment

I have a PIC-based car ignition management system that worked until I decided to make two small modifications to the PCB to fit it into a box. It hasn't worked since, although I have looked at it every way I can think of, I've shut it in a dark box for weeks on end, I've replicated the circuit on a breadboard...... I feel like I have become my signature.

I will make it work. Just maybe not this week.
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Old 10th Oct 2017, 1:40 pm   #24
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Default Re: The perils of homebrewing equipment

I think to _enjoy_ home-brewing you have to either be the sort of person who will sit down and think about, plan and carefully execute something in perfect detail or somebody who turns the soldering iron on first and takes a stoic attitude to burnt fingers, shocks and tickles and ordering two of everything for the inevitable "design fault" or finger trouble.

I'm of the later persuasion usually. However, I've been sending off to China recently to get PCBs made - this requires more forethought as by the time China post, DHL and HMRC have taken their slice a $1 PCB comes out quite expensive. The current one I'm working on is around 9"x12.5" and whilst I am taking my time over the design I fully expect it to be thrown away or at least attacked with a scalpel and soldering iron and it really won't be cheap!

I suppose it is all about expectations, if you're the sort of person who gets upset when the TV or car stops working don't do homebrew. I drive a 35 year old Land Rover and watch a Decca Bradford TV because I prefer tinkering to driving or watch telly!

I recently rebuilt a gearbox over the space of a year and huge expense (my first attempt at anything gear related) of course it didn't work. I was somewhat put out but not discouraged....a couple of weekends, a bad back and I've swapped back the old (perfectly serviceable) box...But, I WILL get the new one working...at some point.

PS: mole42uk was that ignition something you designed or a kit - I've been intending to make something like that for a while now...
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Old 10th Oct 2017, 2:20 pm   #25
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Default Re: The perils of homebrewing equipment

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Originally Posted by dominicbeesley View Post
PS: mole42uk was that ignition something you designed or a kit - I've been intending to make something like that for a while now...
It was a kit from Silicon Chip many years ago designed to give programmable ignition timing for motor car engines in the days before every car was equipped with more computer power than the Apollo spacecraft. Quite suited to my 1972 Triumph Stag, when I eventually get the programmer module to work.
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Old 10th Oct 2017, 3:05 pm   #26
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Default Re: The perils of homebrewing equipment

As a former Land Rover driver I’m seeing a pattern here
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Old 10th Oct 2017, 3:28 pm   #27
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Default Re: The perils of homebrewing equipment

I haven't owned or driven a Land Rover since 2001
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Old 10th Oct 2017, 4:35 pm   #28
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Default Re: The perils of homebrewing equipment

Exactly the same here.
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Old 10th Oct 2017, 6:01 pm   #29
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Default Re: The perils of homebrewing equipment

At the risk of steering this thread to a discussion about the pro's and con's of Landrovers, I used to have to drive many miles in one at work. They are good at what they are designed for but they are definitely not long distance vehicles. They got me a nice comfy Hi-Lux pickup instead a few years ago. Does everything I need to do and more. Quietly and reliably. To return to the topic, I made a really neat wiring loom for a little project once, connected a big nicad pack to power it up on test and was met with a lovely plume of smoke. No fuse in the supply and there was a direct short somewhere. The fumes inside the box managed to damage a pot much later on for some reason too.
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Old 10th Oct 2017, 6:12 pm   #30
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Default Re: The perils of homebrewing equipment

dominic beesley, i will PM you shortly re. one possible cause for a re-built cog-box to fail to work.
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Old 10th Oct 2017, 8:45 pm   #31
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Default Re: The perils of homebrewing equipment

Can we get back to electronics please (or at least electrics!)
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Old 10th Oct 2017, 9:08 pm   #32
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Default Re: The perils of homebrewing equipment

Hi Gents, a very good home brew electronic ignition was published in WW in the 70's. It was pluggable and retained the points; I published a mod to it to isolate the points with an optocoupler to reduce noise pick up and used it on several cars. It really improved the system and a marginal improvement on fuel consumption.

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Old 10th Oct 2017, 9:19 pm   #33
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Arrow Re: The perils of homebrewing equipment

Quote:
Originally Posted by dominicbeesley View Post
I think to _enjoy_ home-brewing you have to either be the sort of person who will sit down and think about it, plan and carefully execute something in perfect detail or somebody who turns the soldering iron on first and takes a stoic attitude to burnt fingers, shocks and tickles and ordering two of everything for the inevitable "design fault" or finger trouble.
I know this remark sounds terribly glib, but it does contain the germ of a truth:
"If you fail to plan, you plan to fail".

However, before I even get near to any serious planning, I always do a search (magazines, general Internet, this very forum, etc.) to see if anyone has already done what I am thinking about - or something near to it. At the same time, I always try to curb my initial enthusiasm by asking myself these three questions: Do I really need this?; Is a ready-made item going to be cheaper?; Is there a fundamental flaw in my general design concept?

Al.
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Old 10th Oct 2017, 9:52 pm   #34
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Default Re: The perils of homebrewing equipment

Quote:
I always try to curb my initial enthusiasm by asking myself these three questions: Do I really need this?; Is a ready-made item going to be cheaper?; Is there a fundamental flaw in my general design concept?
I think most of us use that approach but none of us anticipate the inevitable issues that arise that make us wonder why we didn't buy a ready-made version in the first place!

That said, I often find that there's much more satisfaction from using self-built test equipment (for example) that may even have cost as much as pro stuff.
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Old 11th Oct 2017, 11:07 am   #35
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Originally Posted by kellys_eye View Post
I often find that there's much more satisfaction from using self-built test equipment (for example) that may even have cost as much as pro stuff.
I will agree with you on that. One really worthwhile factor in designing and building your own kit is that you can take future maintenance into consideration: component selection / availability and physical accessibility.

Al.
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Old 11th Oct 2017, 11:15 am   #36
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Default Re: The perils of homebrewing equipment

Well to continue with the amplifier kit I have built, I needed a dummy load for testing and I usually have a bunch of resistors sprawled across the bench. So I decided to build an 8 ohm non inductive load to make things a little neater. the sort of thing you can make at home quite easy. Things like this keep home construction stirring up the grey matter as years advance.
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Old 11th Oct 2017, 11:18 am   #37
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Default Re: The perils of homebrewing equipment

You know, I feel a lot better having read all that. Now I know it's not just me!!

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Old 11th Oct 2017, 11:35 am   #38
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Default Re: The perils of homebrewing equipment

Another minor lack of success last night actually. Decided to go for attempt two of a dummy load for RF purposes. All I want is 5W or so, nothing spectacular. So I'm using 20x 0.6W 1K resistors in parallel. Fudged the mathematics and put 9W through them off the bench supply. They desoldered themselves and fell off the BNC connector

Need a better mounting strategy. Seriously just considering buying an expensive TO-220 packaged 50W resistor and mounting that to the box.
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Old 11th Oct 2017, 12:42 pm   #39
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Default Re: The perils of homebrewing equipment

Almost all of my test gear and lots of other workshop aids have been homebrew, right back to when I was a schoolboy in the mid 50s - transistor testers, IC testers, a Purbeck 'scope, 1 GHz Robin frequency counter, Radcom 200 MHz nixie tube counter in 1974, PM Mosfet multi-meter, signal injectors/tracers, wobbulator, capacitor reformer, gate dip oscillator etc. In recent years, I've posted my projects in the homebrew section of the forum.

Many have been from magazine projects, more recently off internet, sometimes modded to suit my own needs. But because my practical skills far exceed my technical knowledge, though I've had a fair degree of success, I've had my failures. Often projects have failed to work, even though carefully built. Sometimes errors have become apparent, but others not. On occasions, there have been correction in subsequent magazines, but not always.

As a consequence, I have steadily accumulated homebrew projects which look nice on the shelf, but don't do anything at all. Occasionally, people have said 'that looks really neat - 'what does it do?' to which I can only reply 'It doesn't do anything - it's a dust trap'.

Too often when something of interest has caught my eye, I've allowed myself to be distracted, go off on a frolic and start building it, then it gets shelved due to other priorities. Hence, some projects have a long gestation period. I think the record is a Transistor Curve Tracer which appeared in the long since defunct Electronics Today International (ETI) in Autumn 1980. I etched a PCB, built the board, but due to two house moves, never finished it off. More than a year ago I came across it when rummaging in the loft and thought I'd finish it off (35 years after I built the board!).

As is my habit, I made a little comb-jointed box in which to house it, made a front panel, boxed it all up, then in the routine manner, it failed to work. Checked it out and spotted an error on the PCB. Re-did the artwork to correct the error, etched a new PCB, rebuilt it with all new and tested components. Still failed to work. One definition of madness is 'doing the same thing over again and expecting a different outcome'.

Haven't got a clue as to why it doesn't work and I haven't got a clue why I didn't just consign it to history and bin it, but I'm of the 'waste not want not' ration book era, so will spend all day trying to repair a toaster that I could replace for a tenner. I don't even need a curve tracer, and I still don't have one - I have a neat box which calls itself a 'Curve Tracer', but it's just another dust trap.

I'm still at it - I recently spotted a circuit on internet for an 'IF Alignment Aid'. I don't want one, I don't need one - I rarely find I have to realign IFs and if I do, I'm sorted for signal generators. It's a 'one trick pony' in that it will only align IFs - not the front end of a set, so has its limitations, but then it just uses two ICs and two transistors and looked a neat little circuit for which to develop a PCB - more of that another time. These days, it's highly likely that some device is readily available from the orient for under a fiver post free which would do the job far better. Still doesn't stop me.

I'm sure that a clinical psychologist could put a name to this trait, but I just call it 'enjoying myself'.

'Enjoyment' is a subjective term. I have a chum who is an angler. It's raining, windy and miserable here today. Odds on he'll be sat on a river bank somewhere under one of those 'Billy no-mates' umbrella jobbies and even if he doesn't catch anything, he'll tell me that it's the most enjoyment that he can derive without taking his clothes off. Ho hum.

Waffled and dribbled David.
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Old 11th Oct 2017, 12:49 pm   #40
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Default Re: The perils of homebrewing equipment

That curve tracer looks quite interesting. I don't need a curve tracer but I'd enjoy building one and the visualisation that it produces of the transistor characteristics.

Very interesting (i.e. cheap!) method for generating the steps by slowly pumping up C1.
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