Electronics Advice

[Mark]

you get get 2x Panasonic CAPACITOR, 1500UF, 6.3V inc delivery for £2.59 on ebay

[Martin Brown]

Probably that the 1500uF part was 0.01p cheaper!

Nominal 1500uf could easily be anywhere from 1200uF to 1800uF with a few outliers outside that range. I doubt if any switched mode PSU design is so sensitive to choice of final storage capacitor that it would suffer more than a slight

[Brian Gaff]

I'd go for the larger one, assuming it fits. If the psu cannot stand the switch on surge its not been designed very well! Brian

[Brian Gaff]

Yes agreed, this is capacity we are talking about after all. One word of warning before you commit a new capacitor. look at the actual voltage across it and make sure ists not high or A/C, which might point you to the original cluprit, in the former case a voltage regulator, in the second the rectifier. Brian

[meow2222]

Either may be the case. Generally speaking though, more capacity at a given voltage costs more. So 1000uF cap can not be assumed to have enough capacitance.

Tolerance is a bit of a red herring here, 1000 and 1500 both have a tolerance range, with the minimum value 2/3 as much for the 1000.

OP, this is a diy group. You're asking about electronics.

NT

[CB]

Yes but I am proposing a DIY repair :-).

(Ok so it was a little OT - but I have seen worse on here - and I did get some very helpful advice)

[Peter Andrews]

Given some of the other subjects on here, e.g. Rhine River Cruises, Shale Gas, Night Attack on ISIS, I can't see any problems with asking an electronics question - it is electric after all, albeit possibly a little more complicated than house wiring! ...and he has had some excellent answers and, even more important, explanations.

Peter

[charles]

and - wasn't Maplins set up as a DIY electronics supplier - not that that they are as much nowadays.

I have a solderting iron and have had since the 1950s.

[Andrew Gabriel]

Yes, in particular they did kits of parts for the projects in Practical Electronics, Everyday Electronics, and Electronics Today International magazines (but never Elektor, AFAIK).

Then they had a couple of goes at launching their own magazines with more projects, each of which ran for a few years; Maplin Magazine, and Electronics and Music Maker.

At some stage (latter 1980's?), it became unfashionable for school children to teach themselves to build electronic projects, and most of these magazines vanished. Elektor is still going.

I used my dad's 1950's 25W Solon until I was at university and first used a temperature controlled TCP Weller, and so bought myself one out of my student grant. Still works fine, and one of the best purchases I ever made. However, it was good to start off with a crappy corroded bit soldering iron, because it means I can now do very good soldered joins with any quality of iron, or even a screwdriver heated on the gas stove, although it's much nicer to use a good iron of course.

[Johny B Good]

Wrong! That gives 680.

The values aren't critical. In most cases, you could substitute a

1500 with a 1200 (or even a 1000 - low C with low ESR is far better than the original C with excessive effective series resistance).

A more conservative choice is to use a larger value, say a 2200 for a

1500. The values chosen by the designer are those deemed to be a bare minimum, taking component tolerances and the limitations of an E6 or E12 series component value choice into account.

The design lowest, worst case value might be 820 and the designer will therefore choose a 1000 to take account of the traditional

+80/-20% capacitance value tolerance typically used by the manufacturers of electrolytic capacitors. He might even choose a 1200 or 1500 value to give his design a little more of a performance margin over and above the bare minimum spec.

The only other aspect is the voltage rating. You can choose one equal to or greater than the original value (6v3 in this case, so a 10v or

15v rated cap will serve, space allowing).

The downside with exceeding the original voltage spec is typically a physically larger capacitor (fatter or taller) which may or may not fit the allocated space on the PCB.

Sometimes you can choose a 6v3 cap over a 10v one where it's quite obvious that the 10v used was just simply on account it was what was available from stock for the job, typically a smoothing cap on a 5 or lower voltage supply rail where a 6v3 or 4v0 would have been the optimum choice.

The manufacturer can reduce inventory costs by ordering just one lot of 10v caps in 100,000 off quantity than say 15,000 4v plus 30,000 6v3 and 60,000 10v caps per production batch of finished goods so it's not unusual to see caps fitted with massively overspecced voltage ratings, particularly on the 5 and 3v3 rails of an ATX PSU or similar kit with a wide range of voltage rails. If you know what voltage the cap is actually being subjected to, you can safely widen your choice of replacement capacitor options.

[charles]

that's when I bought mine.

[Johny B Good]

If, like me, you've accumulated a collection of scrapped circuit boards (MoBos in my case), that's an excellent way to build up a good stock of replacement caps (Intel MoBos seem to provide the best quality 'recycled' caps but other makes can be good too - the presence of a few rogue caps doesn't have to mean the other makes of 'good caps' on the board can't have a useful 'second lease of life).

One of these days, when the XYL is going to be out of the way for a good few hours, I'm going to turn the kitchen into a MoBo recycling plant, yet again! It's just a case of laying newspaper on the kitchen floor onto which I can flick the components after heating each board over the largest burner on the gas hob to re-flow the solder.

It also helps to be armed with a few suitable pairs of pliars, a screwdriver or two and a pair of heavy duty leather workman's gloves to deal with the more 'interesting' components.

The XYL needs to be absent for a few hours just so you have enough time to leave the windows wide open to dissipate the worst of the acrid fumes to take the edge off the lingering smell of your recycling operations (assuming you're expecting your tea to be laid out on the table come teatime).

[whisky-dave]

I have aone here perhaps more lurking.

This one dated Dec. 1983 to jan. 1984 price 70p Projects include Stop Burglars, full size keyboard for ZX specrum.... plus others.

Just found aN everyday electronics oct 82 with 2 free transistors still in the bag stuck to tHE front cover. BCY65EP, 2N3905.

Yes computers started taking over and a lot of builders were getting sick of projects not working, sort of killed it off for me. But as you get further into your teens other things demand attention.

[meow2222]

Long as they're lead-free, or you;ll get tiny lead droplets everywhere. Hence I wouldnt use the kitchen.

NT

[Johny B Good]

Although that's a valid concern, quite often it's on account that was the nearest value of capacitor that exceeded the minimum value requirement for the circuit that the manufacturer kept in stock which the designer would have been mindful of when laying out the PCB.

Economies of scale involve the savings on bulk ordering. Often, it would be significantly cheaper to order 100000 1500 microfarad 6v3 caps than to order 50000 of 1000 and 50000 of 1500 microfarad 6v3 caps.

For electrolytic capacitors, the most common increment of values within each decade is the E6 range (1.0 - 1.5 - 2.2 - 3.3 - 4.7 - 6.8

- 10.0 etc) and the commonly used tolerance is -20/+80%.

Electrolytics are never used in circuits where even a +/-10% tolerance matters and only a minimum value is of concern to the designer who will, in the light of this knowledge, specify a value that exceeds the theoretical minimum by at least 50% if not more like

100 to 150% of the 'design value'.

All in all, it is exceedingly improbable that using a 1000 microfarad cap in place of a 1500 one is going to cause any problem.

[fred]

In article , CB writes

Couldn't agree more, I view DIY electronic repair as very much on-topic for this group.

[Cursitor Doom]

Wrong! 687.5 actually. ;->

[Bob Eager]

That calculation is OK within a 20% tolerance! :)

[Graham.]

I thought it was a strange comment to make, even for a Google Grouper.

[Graham.]

39 posts in this thread about a PLA, and not one suggesting the OP should run a cable. I think we are slipping ;-)