Bob Parker ESR Meters

[PeteS in CA]

Re: Bob Parker ESR Meters

ESR is a very variable kind of thing, and don't forget that it changes quite dramatically with temperature (ESR drops as temperature rises). This is one reason why it's better to check capacitors in-circuit if possible. Otherwise the heat from de-soldering them makes the ESR decrease until they cool down again, making them look better than they really are.

Ripple current is a maximum rating for a capacitor. It's the largest AC current you can safely pass through it. That's what mA RMS means. It's like voltage rating .... it's about what the circuit's doing to the capacitor, not a characteristic the capacitor itself has.

Lytic caps' ESR have a strong negative tempco - lower ESR at higher temp and higher ESR at cold temps. Caps with water-based electrolytes are typically only rated down to -40C, while non-aq low Z types are typically rated down to -55C. At 25C, good low Z caps have a lower Z/ESR than their max rating. Theoretically, the ripple current rating means that if you run caps above that rating, hydrogen gas will be produced, leading to premature failure. I don't recommend exceeding that rating on a long-term, full-time basis, but it is a conservative rating. I've run caps in one of my tests at multiples of their ripple current rating (at room temp) and had some last for thousands of hours. Re discharging caps, I have a jig made of two power resistors in series formed like tweezers so I can discharge the caps I'm testing while gripping the resistors by their bodies (IOW, I don't get zapped, ). I discharge every cap (and let them cool for two hours - it's an engineering tests) before checking them on my LCR meter.

[starfury1]

Re: Bob Parker ESR Meters

Hi all

A page on capacitance and ESR Here

Bit on the techie side and uses maths you may have to search out the definitions of some terms, properties to make sense of it.

heres another page with links off it including Bob Parkers page

ESR Testing

Hope it helps anyway

Cheers

[akuhon]

Re: Bob Parker ESR Meters

Hi Bob...

Thanks for your comment and I really thank you for making this great device.


Cheers,

[Bob Parker]

Re: Bob Parker ESR Meters

Thanks Bob,

That helps ......
How about a new / fresh (never used) caps ? If I test with this ESR meter, will the result be valid ?

Thanks ...

I'm not really an 'ESR Meter Guru' . I'm just a technician who was repairing switching power supplies and I desperately needed to know the condition of their capacitors. I'm not an expert on every detail of electrolytic caps. I can only tell you my experience after using the ESR meter since 1995.

Most new electrolytic caps have an ESR a bit below what their datasheets say. It will stay low for a very long time unless the capacitor has been operated at a temperature considerably above room temperature, especially if it has high ripple current through it.

Of course this doesn't apply to the billions of faulty electrolytic caps which are the reason that this Badcaps forum exists! They will keep getting worse as long as they have DC across them.

So the ESR of an unused electrolytic cap will be very similar to what it would be if it had been in use for a while, under normal temperature/ripple current conditions.

There is a lot of information about electrolytic caps and what to expect when using an ESR meter in the kit notes for the Dick Smith ESR meter. Anyone can download it from

But I don't have time to answer lots and lots of question about it.

[akuhon]

Re: Bob Parker ESR Meters

Thanks Bob,

That helps ......
How about a new / fresh (never used) caps ? If I test with this ESR meter, will the result be valid ?

Thanks ...

[Bob Parker]

Re: Bob Parker ESR Meters

Hai Bob,

I just got your device ..... it's really helpful.

I'm identifying several capacitors available from the electronic market component .....
So, now I'm not a afraid of counterfeit / fake / rebadge product....

Here's Rubycon cap... the device give the same result as the datasheet (0.046 ohm) ...



But I also see, in every capacitor's datasheet, there's a measurement of ripple current (mA r.m.s.)
Do you think this measurement is also important ?
How to do it, any idea ? Or maybe you can make it, combine with your existing ESR Meter for the next version (Mk.III) ?

Cheers,

The data sheets generally tell you the highest ESR which can be expected for a specific capacitor type/model. Mostly they're a bit below that figure at 25 degrees C.

ESR is a very variable kind of thing, and don't forget that it changes quite dramatically with temperature (ESR drops as temperature rises). This is one reason why it's better to check capacitors in-circuit if possible. Otherwise the heat from de-soldering them makes the ESR decrease until they cool down again, making them look better than they really are.

Ripple current is a maximum rating for a capacitor. It's the largest AC current you can safely pass through it. That's what mA RMS means. It's like voltage rating .... it's about what the circuit's doing to the capacitor, not a characteristic the capacitor itself has.

[Bob Parker]

Re: Bob Parker ESR Meters

Unfortunately, I missed the sale on that particular version T2200 (meter), but I did land it's little brother T1976 (minus meter), BTW thanks for the pointer(s) always appreciated

The 17w ~ 25w hobbist irons are quite nice IMHO, but their tips don't make fine/detailed soldering easy by any means... but I digress

Temperature controlled irons (set to a sensible temperature of course!) are almost essential when you're working with PCBs. Uncontrolled irons are OK for tinning the ends of bits of cable etc which are pretty hard to damage with excess heat.

[akuhon]

Re: Bob Parker ESR Meters

Hai Bob,

I just got your device ..... it's really helpful.

I'm identifying several capacitors available from the electronic market component .....
So, now I'm not a afraid of counterfeit / fake / rebadge product....

Here's Rubycon cap... the device give the same result as the datasheet (0.046 ohm) ...



But I also see, in every capacitor's datasheet, there's a measurement of ripple current (mA r.m.s.)
Do you think this measurement is also important ?
How to do it, any idea ? Or maybe you can make it, combine with your existing ESR Meter for the next version (Mk.III) ?

Cheers,

[tazwegion]

Re: Bob Parker ESR Meters

Unfortunately, I missed the sale on that particular version T2200 (meter), but I did land it's little brother T1976 (minus meter), BTW thanks for the pointer(s) always appreciated

The 17w ~ 25w hobbist irons are quite nice IMHO, but their tips don't make fine/detailed soldering easy by any means... but I digress

[Bob Parker]

Re: Bob Parker ESR Meters

No worries, I've actually been weighing up my choices between a basic 25w Scope, a DSE (entry level) soldering station & a 13w 'Goot' pencil iron

I've briefly used one of the basic DSE soldering stations (with a little meter showing the temperature) and I thought it was pretty good.
It's always hazardous soldering PCBs with an uncontrolled iron because they tend to get awfully hot and de-laminate the copper foil. But a temperature controlled one operating at around 350C generally does the job very nicely.

[tazwegion]

Re: Bob Parker ESR Meters

Whew... thanks for that. I've been supporting that kit since early 1996 and I've seen some real disasters caused by huge overheated soldering irons. I was hoping this wouldn't become the latest one.

No worries, I've actually been weighing up my choices between a basic 25w Scope, a DSE (entry level) soldering station & a 13w 'Goot' pencil iron

[Bob Parker]

Re: Bob Parker ESR Meters

I really had no intention of using the 40w iron, as I said it's too heavy duty for this delicate application, I generally only use the 40w on automotive jobs

Having the 25w burn out like it did is kinda' a blessing in disguise, as now I'll be able to purchase something significantly better, I mean when you consider it came with a DSE kit package I purchased more than 10 years ago... it's been productive

Thankfully the symbol on the silk screening combined with the photos & schematic provided in the guide booklet steered me in the right direction... BTW have no fear I'm not out to butcher your kit, it's only useful to me functional

Whew... thanks for that. I've been supporting that kit since early 1996 and I've seen some real disasters caused by huge overheated soldering irons. I was hoping this wouldn't become the latest one.

[gdement]

Re: Bob Parker ESR Meters

Yeah, using a 40w iron is kind of rough. That was what I used, and I burned a few pads along the way. You have to move pretty fast for it to work, a little too fast for me to handle it sometimes. If the iron is there more than a couple seconds it'll fry.

[tazwegion]

Re: Bob Parker ESR Meters

I really had no intention of using the 40w iron, as I said it's too heavy duty for this delicate application, I generally only use the 40w on automotive jobs

Having the 25w burn out like it did is kinda' a blessing in disguise, as now I'll be able to purchase something significantly better, I mean when you consider it came with a DSE kit package I purchased more than 10 years ago... it's been productive

Thankfully the symbol on the silk screening combined with the photos & schematic provided in the guide booklet steered me in the right direction... BTW have no fear I'm not out to butcher your kit, it's only useful to me functional

[Bob Parker]

Re: Bob Parker ESR Meters

The values placed on the MKII silk screening were a little confusing @ first for a novice such as myself... I mean 100R??? equates to what exactly? thankfully the included guide contained a helpful schematic (see inset)

Sadly... this is as far as I've got with the kit as my (former) faithful 25w iron has fizzled out, dunno' about everyone else... but I figured the 'other' 40w iron I have may be a little too 'heavy duty' for such a delicate undertaking

Please don't try to use a non-temperature-controlled 40W iron to build the meter. It's sure to burn component pads off the board and do other damage. When I designed it, I thought only experienced repair technicians with soldering stations would be building (and using) it. [Whimper].

[tazwegion]

Re: Bob Parker ESR Meters

The values placed on the MKII silk screening were a little confusing @ first for a novice such as myself... I mean 100R??? equates to what exactly? thankfully the included guide contained a helpful schematic (see inset)

Sadly... this is as far as I've got with the kit as my (former) faithful 25w iron has fizzled out, dunno' about everyone else... but I figured the 'other' 40w iron I have may be a little too 'heavy duty' for such a delicate undertaking

[Bob Parker]

Re: Bob Parker ESR Meters

There, got cables now too

Just to make sure, is this the way the safety diodes are supposed to be installed? (the two vertical things being the wires going to the test lead sockets)

Yes, that is correct.

[Per Hansson]

Re: Bob Parker ESR Meters

There, got cables now too

Just to make sure, is this the way the safety diodes are supposed to be installed? (the two vertical things being the wires going to the test lead sockets)

[Per Hansson]

Re: Bob Parker ESR Meters

The other thing is you might want to
get into the habit of discharging Higher voltage caps as a matter of course for your own safety
as much as for the meters.

When you get bitten by a cap sitting at 350 Volts DC you will know what I mean

Look what I found in the mail



I also got the testleads, they where not kiddin though, with testleads it's really only the leads, no cables!
Meh, guess I'm keeping the postal office busy atleast
Ordered some nice gold plated cables, also managed to order only one diode when I was fully aware I needed two!
Meh, see my blog post to see what all the whine is about today

[starfury1]

Re: Bob Parker ESR Meters

Hi all

I thought I should mention this
(I don't think it has been mentioned)

If you use the meter near a monitor or TV that is going it will probably give spurious readings

So please make sure you are not near one when using it.

Not sure how bad with a TFT but probably ditto for them too

To get an idea,
try it for your selfs and at a few feet distance too.

It is mentioned in the notes somewhere or was it on Bobs site probably both.

This is something to beware of and its something you can easily forget too,
as we tend to have a computer or 2 close to our work bench.


The other thing is you might want to
get into the habit of discharging Higher voltage caps as a matter of course for your own safety
as much as for the meters.

When you get bitten by a cap sitting at 350 Volts DC you will know what I mean

Cheers