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unknown ceramic capacitor value

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doval

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Greetings
I bought a 'variety pack' of 50V ceramic capacitors off amazon, shipped from china of course. All of them were marked enough that I could tell what values they were except one packet. Using a magnifying glass the 'unknowns' appeared to be marked with a 01 vertically instead of horizontally. After taking a picture with my phone and blowing it up on my computer it appears maybe to be a .1 , which I might deduce would be a .1pF capacitor value? I just wanted some experienced input on this as I've not seen a ceramic cap with the printing vertically, and want to be sure I've got it right.

Here's a pic, thanks in advance for taking the time to read this, and bigger thanks if you know for sure what the answer is! :D
01_Ceramic_Capacitors.jpg
 
0.1pF is the capacitance between two short wires that are 1m apart! It is NOTHING. I suspect that a capacitor marked "1" was the first capacitor used in a kit.
 
I suppose that's possible. But I don't think that's it. All the other capacitors were labeled 103,104,201,223,204, etc, horizontally, as expected for this type of capacitor. I think this is supposed to represent a value of some sort, not a number of an item used in a kit.
 
Look at this link. It suggests 1pf
 
Either 1pF or 0.1uF. Measure it with a cap meter, that's really the only way you're going to know for sure.
 
That fat i with the large dot looks familiar to me as a logo. I put the odds of it being the value in a vertical format at zero.

If you don't have a capacitance meter but do have a 555 and a proto board, whip up an oscillator, try various resistors until it runs, then measure the freq and calculate. That's sorta kinda what cap meters do.

ak
 
I expect it is a 1pF capacitor. Seems like the most obvious solution.
 
Hi,

1pf is a small value so if it is really 1pf then you will probably have to start with a 10pf cap and after you test that add the supposed 1pf in parallel and note the effect. A small effect indicates it is probably 1pf, a large effect means it is a larger cap. If you use the oscillator, note the frequency change.
 
I think two most probable values are 1pf or .1uF. Simply placing the cap in series with audio signal (eg. between cellphone and earpiece, .1 would pass audio but 1pf would not) would clear about 1pf or .1uF. I guess the dot above '1' is to indicate that the 1pf and 'high voltage'.
 
I also vouch for the oscillator feature. Of course, we are assuming that you have a way to measure frequency accurately.
Bear in my though, that if you build the test circuit in a proto or vero board, the stray capacitance may be larger than 1 pF.

I have also purchased electronic component's "grab packs" of everything from transistors to capacitors and everything in between.
It is a good way to save money for the hobbyist.

Having said this, I would advise you to invest in a LCR and/or a semiconductor tester. They are inexpensive.
Also many DMMs have LC functions in addition to the resistance ranges.
 
My Fluke multimeter measures its own stray capacitance without any leads on it of 150pF. With leads it shows 200pF.
 
Other pointers to value would be the temperature tolerance marking. In the case of your photo, it looks like they have black painted tip's, meaning np0 type. You can often find the common value range from that, then based on other device markings, narrow down the actual likely value within that range.
 
It is best to be safe than sorry you need to test them. If you have no meter that will test them build a timer circuit using a resistor, capacitor and NE2 neon light. The DC power supply charges the capacitor at a certain speed through the resistor. Then the charge in the capacitor reaches a certain voltage it discharges through the neon so the light will blink 1 time. If you use a known value capacitor and a variable resistor to set it to blink once every 5 second they test a unknown capacitor. If the unknown capacitor blink 2 times slower the capacitor value is double the value of the known capacitor. Use basic math to calculate the difference of the flash rate of the neon for different caps to determine their value. It will surprise you how accurate this is especially if you use a long flash rate of 50 seconds then compare that to a unknown capacitor with a higher or lower flat rate.
 
Last edited:
1pF x 10M= a charging time of 10 millionths of a second. You will not see any flashing.
 
1pF x 10M= a charging time of 10 millionths of a second. You will not see any flashing.
Is this a same calculation as pre-emphasis?
 
All right, who let fact into the room?
1pF x 10M= a charging time of 10 millionths of a second. You will not see any flashing.

Unless you are Superman or Time Warp Man :)

But seriously, 1pf is not easy to measure. That's almost like trying to measure a resistance of 0.001 Ohms. Yeah, you can do it, but it takes special care.

My $100 meter doesnt even go that low, but it can measure 10pf so i measure the 10pf and get a reading, then parallel it with 2pf and get another reading, then use the formula for two caps in parallel:
Cp=C1+C2
where Cp is the total capacitance and C1 and C2 are the two actual capacitors.

C1 is the known capacitance which i take a reading first, and say i get 11pf, then C1=11pf, so then i parallel with unknown then get:
Cp=11pf+unknown_pf
and say this second reading is 13pf, then we have:
13pf=11pf+x_pf
and solving for x_pf we have:
x_pf=13pf-11pf
and we all know that 13-11 is equal to 2, so the unknown cap must be 2pf.

But what if the unknown was higher. Then i would have seen maybe:
20pf=11pf+x_pf
so here the x_pf (the unknown cap value) must be 9pf.

Note that i had to take a reading first with the known capacitor.

With a frequency oscillator like the 555 the frequency will be close to following the capacitor value in proportion to that capacitor value. So say we connect a 100pf cap with some resistance (possibly variable) and we see a frequency of 1000.0 Hz. If we connect a 10pf in parallel with that we have:
Cp=100+10 (in picofarads)=110

and 100/110=0.90909

so if we had a frequency of 1000Hz to begin with, the new frequency would be 1000*0.90909 which would be 909.09Hz which might show up as 909.1Hz.

This means if we measure a frequency of about 909Hz then the unknown cap is about 10 percent of the known cap. So we have the formula:
C_unknown=(F1/F2-1)*C_known

where F1 is the frequency with only the known capacitor connected, and F1 is the new frequency with both caps connected.

If the new frequency happened to come out to 500Hz, then we would have:
C_unknown=((1000/500)-1)*100=100

so the unknown cap would have to have been 100pf also.

Here is a list of factors for 'new' frequencies of 900Hz down to 100Hz:
900Hz, C/9
800Hz, C/4
700Hz, (3*C)/7
600Hz, (2*C)/3
500Hz, C
400Hz, (3*C)/2
300Hz, (7*C)/3
200Hz, 4*C
100Hz, 9*C

where C is the known capacitor here and the original frequency was 1000Hz.
If the original frequency was 10kHz instead, then just multiply all those frequencies by 10.

So for example if we measure 800Hz with a known cap of C=100pf, then the unknown cap must be C/4 which comes out to 25pf.
But if we measured 200Hz, then the unknown cap must be 4*C=400pf, but we usually dont have to measure larger caps this way.
 
I actually think the whole thing is a logo. Something which looks like a pic over an i or an l. You did say you blew it up, so it's possible it's a 1 pf capacitor.

103,104,201,223,204 are easy: 10 with 3 zeros * 1e-9, so 10000e-9 Farads. 3 zero left, you get 100 milli-farads and 3 more 0.01 uF

Another way to look at is is 10 (add 3 zeros) pf.

I'd look at the physical size too of similar capacitors.

Capacitors can be marked by color. **broken link removed** I did notice the one dot on the edge which might indicate voltage.
 
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