No way! That's above and beyond what I wouldve expected and mostly why I love this forum. You crammed in those replied in the time it took me to say "The underline in those cap markings is also an astute observation that I'd have missed otherwise. Good shout."

I dont even know why I care. This is just a result of 10 days of being housebound, I'll be fighting with the skirting boards next at this rate (they're not quite flush, I know it and they know it too. Nobody else see's it yet but they will).

Good to know all the same though. That said  you called into question the input impendence of my meter which is yet another question I've never thought I'd have to answer (fwiw I just looked it up and it's 10M, not that I'd have known before that matter for anything) but I figure regardless id notice a difference in reading.

Damn. Cheers. I think my question has been answered but somehow i have more questions on subjects I hadn't even entertained.

Cool it's sorted out.

QuoteI know it and they know it too.

FYI, took me a while to find this .   As an example of annoyance, here's a 100nF with a 104 marking *but* with an underline,



I think you can get 101 with an underline for 100pF but I'm *not* aware of 100 with underline meaning 10pF.  Clearly 10 with an underline is 10pF.

I'll throw out a challenge if someone can find cap marked 100 *with* an underlined under the 100 and measuring 10pF.

There was a time we did not use xxd format, only literal, so no need for an underline. If that's even what the underline means, which is now questioned.

This would be the 1950s, through the 1960s in the US, and into the 1970s when buying odd-lots in the alleys of Brooklyn or LA. Which is when/where some classic amps and pedals were built.

I don't recall ever seeing a 3-digit number represent a 2-digit value on a ceramic cap, vintage or modern.  I just looked at some of my Tayda caps, the 10pF caps just say "10", while the 30pF caps say "30".  I have always assumed the underline was there just to make it clear how it should be read, right side up, so 6s aren't mistaken for 9s, etc.

You might measure a pF range cap in a DMM if it has a zero function (so the stray cap reading is nulled out). Then you need the test cables set rigid so that stray capacitance doesn't change. However, for the lesser values, I'd expect you would struggle to jig it up rigidly enough and RFI/EMI will make a mess anyway. If it turned out to be 100pF, you'd probably get a good enough result to say it's very probably 100pF.

Some types of cap I have never seen with other than a literal value assumed to be pF. Such as 560 on mylar or mica is 560pF.
Some are confusing, but if I see 101 it's definitely 100pF and if I see 100 it's also 100pF. A ceramic disc cap multipack of the same range provided ...471, 221, 101, 47, 22, 10.

Quote from: anotherjim on April 01, 2020, 05:26:18 AM
Then you need the test cables set rigid so that stray capacitance doesn't change.

Quote from: Rob Strand on March 31, 2020, 06:54:26 PM(Even if it does measure down to pF you will need to subtract off the capacitance from the meter and meter leads.)

Sorry to bring up 'my' dmm again, but with that one you can only measure capacitance by inserting the capacitor into the socket on the dmm, like you would with transistors.
When taking a cap out of the circuit to test, it is rather inconvenient because the legs are too short to reach the contacts inside the socket.

QuoteSorry to bring up 'my' dmm again, but with that one you can only measure capacitance by inserting the capacitor into the socket on the dmm, like you would with transistors.

Part of the motivation for those capacitors connections is convenience and part is it forces you to keep the legs short and keep the stray/lead capacitance low.    That means the manufacture can zero any stray capacitance using an internal trimpot  at manufacture.  The meter has its own internal stray capacitance on the PCB which is relatively fixed and is removed in the process.   Some meters might have more than one zero trimpot, a separate one different ranges, or one for low-range and another for everything else.

On some meters you might find the device doesn't measure exactly zero on all ranges when no cap is inserted.   For maximum accuracy it's best to subtract off any zero errors manually regardless of their source.   For small valued caps even the proximity of you hands and fingers can affect the reading.
   

Quote
When taking a cap out of the circuit to test, it is rather inconvenient because the legs are too short to reach the contacts inside the socket.

Yes, you get the same problem with transistor gain testers.   The best way around that is to make an extension lead (s).  Get a cap lead off-cut for poking into the meter socket then solder a short-ist piece of thin flexible wire to the cap off-cut and an alligator clip.  For some caps you can get away with only one lead.    (These leads end-up breaking after while.)

Best not to touch the leads for when measuring.

Quote from: Rob Strand on April 01, 2020, 05:35:01 PMFor maximum accuracy it's best to subtract off any zero errors manually regardless of their source.     

I'll keep that in mind next time.

Quote from: Rob Strand on April 01, 2020, 05:35:01 PMThe best way around that is to make an extension lead (s).  Get a cap lead off-cut for poking into the meter socket then solder a short-ist piece of thin flexible wire to the cap off-cut and an alligator clip. 

Yes, that's how 'solved' it for those cases.

While we're at it, would there be a specific reason, as far as capacitance measuring goes, to make the contacts in those sockets so thin? There's also very little spring tension on them.
It is a very cheap meter after all but the little plates inside the sockets almost look like they were made of aluminum foil (a bit exaggerated).
If I would hold the dmm upside down and shake it a bit, an inserted cap would surely fall out.

QuoteWhile we're at it, would there be a specific reason, as far as capacitance measuring goes, to make the contacts in those sockets so thin? There's also very little spring tension on them.
It is a very cheap meter after all but the little plates inside the sockets almost look like they were made of aluminum foil (a bit exaggerated).
If I would hold the dmm upside down and shake it a bit, an inserted cap would surely fall out.

Sockets like that are more for convenience.   It's probably a delicate balancing act mechanically to handle thin leads, thick leads and bent leads.  If you make the spring too strong you can't get the thick leads without bending them.  Too weak or wide and they fall out.   Maybe on your meter they haven't got the balance right.   

I have seen a few higher end meters with similar connections to yours, but better/stiffer connectors.   The medium priced LCR meters use Banana Connectors and you have to sort out how to connect it (and handle stray capacitance).   The high-end HP/Agilent/Keynote LCR meters use 4x BNC connectors.  This helps accuracy but is nowhere as convenient as the slotted socket.  They do offer attachment modules to make connections easier.