What Capacitors Should I Use

Thread Starter

bumba000

Joined Oct 7, 2015
89
Hi All,
I have been working on this 9-band filter found elsewhere on the interweb. I have the buffer and the first three filters built. It works pretty well, but I'm using electrolytic caps. Looking at the schematic the capacitors used appear to be tantalum. The part used in schematic is: C-EUC0805K
Is this correct? Are all caps supposed to be tantalum?

I understand that it sounds like I already know the answer is yes - tantalum. The problem is that I can not find any through hole 10nF tantalum caps. I can find them in surface mount. Is there such a thing as through hole 10nF Tantalum capacitors?

Thank You,
John
 

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dl324

Joined Mar 30, 2015
12,917
Didn't look at your attachment, but the caps band pass/notch filters would typically be low leakage precision types.
 

Thread Starter

bumba000

Joined Oct 7, 2015
89
I understand your response, but then again I really don't. I am looking at SMD tantalum caps now. Is this what I need?

Thank You, John
 

MrChips

Joined Oct 2, 2009
23,875
Hi All,
I have been working on this 9-band filter found elsewhere on the interweb. I have the buffer and the first three filters built. It works pretty well, but I'm using electrolytic caps. Looking at the schematic the capacitors used appear to be tantalum. The part used in schematic is: C-EUC0805K
Is this correct? Are all caps supposed to be tantalum?

I understand that it sounds like I already know the answer is yes - tantalum. The problem is that I can not find any through hole 10nF tantalum caps. I can find them in surface mount. Is there such a thing as through hole 10nF Tantalum capacitors?

Thank You,
John
Don't upload .sch files. Post graphics files such a .jpg, .png etc.

Don't use tantalum for such applications. Mylar or other poly- type capacitor is fine.
 

Thread Starter

bumba000

Joined Oct 7, 2015
89
I included the sch so that you can see what I'm seeing when clicking on a component. That doesn't work with jpg, png etc...

I have used ceramic capacitors but the circuit doesn't seem to work properly with them. Could this be due to the virtual ground? 50hZ, 120hZ, 250hZ etc... pretty tight I guess.
 

Thread Starter

bumba000

Joined Oct 7, 2015
89
Ok, so I haven't been able to find a capacitor in a schematic that uses a symbol like the caps in this schematic. I've researched the "device" shown in properties when clicking on cap symbol. It says that it's a tantalum capacitor. The schematic seems to suggest polar direction. When I tried ceramic caps, it didn't work. Using electrolytic works but I don't have any 10nF sizes. I ordered today 120 tantalum SMD caps. 10nF, 100nF and 1uF. It was a great deal anyways, but I see you're saying not to use them. I have mylar on hand but of course not the required sizes. Also they don't care about polarity. will that be a problem in the particular circuit?

Thank You, John

 

MrChips

Joined Oct 2, 2009
23,875
When I tried ceramic caps, it didn't work. Using electrolytic works...
Then something isn't right. Maybe you used the incorrect capacitance values.

...but I see you're saying not to use them. I have mylar on hand but of course not the required sizes. Also they don't care about polarity. will that be a problem in the particular circuit?
Yes.

You need to use non-electrolytics in any kind of audio frequency filters.

There are places where we use electrolytics such as in power supply filters and in DC blocking capacitors between stages. We use electrolytics because non-electrolytics would be enormous in physical size. In all such cases, you have to ensure that the polarity of the bias across the capacitor matches the marking on the capacitor. In other words, the more positive potential in the circuit goes to the positive lead of the capacitor.
 
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