What would be a good capacitor?

[tsteele93]

If I were to use a flashlight driver and wanted to add a cap to smooth things out, what would be a good recommendation for a cap to do this? Anyone have a goto capacitor that they use in this type of circuit?

 

[Meatball]

Well, ceramic caps are all the rage at the moment, but they are brittle and can vary widely with temperature. I would personally spring for some 25V rated 47uF cap. Its frankly more than enough capacitance, but I sometimes appreciate overkill.

 

[lasersbee]

If I were to use a flashlight driver and wanted to add a cap to smooth things out, what would be a good recommendation for a cap to do this? Anyone have a goto capacitor that they use in this type of circuit?

That would depend on the frequency and amplitude
(voltage) of the ripple you are trying to get rid of....
A scope would help chose the one you want..

Jerry

 

[AnthoT]

47uF 25V caps work great but it depends what exactly

-Anthony

 

[Kizdawg]

I was wondering the same thing about a LM317 driver build I have a bunch of caps salvaged from old asus motherboards there 6.3v 1500mF, 16v 1200mF, 16V 100mF and 6.3V 1000mF the 2 driver builds I read recomended 35V 47mF and 16V 10mF which are quite different :thinking:

 

[tsteele93]

I was wondering the same thing about a LM317 driver build I have a bunch of caps salvaged from old asus motherboards there 6.3v 1500mF, 16v 1200mF, 16V 100mF and 6.3V 1000mF the 2 driver builds I read recomended 35V 47mF and 16V 10mF which are quite different :thinking:

Well someone correct me of I am wrong, but I'm assuming the voltage is pretty much a given. We shouldn't be working with more than 12V in any scenario. So add a little headroom and we should be good. Just need to figure the capacitance, right?

 

[Sigurthr]

The standard wisdom is to always select maximum values twice that of what it will actually be subjected to. 16V caps are fine for 2 Li-Ion cell linear builds but I'd want >34V caps for any boost driver.

When you're parallel filtering nonresonant DC circuits, you can't have too much capacitance imo. You'd select the largest (value) cap you can fit in your application. I've used 50V 47uF mostly due to ease of procurement.

 

[Hemlock_Mike]

I've always found that if lead lengths are kept short, meaning minimal circuit
inductance, minimal compensation is needed. Keep impedance low and there should be no problems.
HMike

 

[rhd]

I'm not sure why I stopped doing this, but I used to always solder a 10uF 16V ceramic SMD cap across diode leads.

 

[Sigurthr]

I'm not sure why I stopped doing this, but I used to always solder a 10uF 16V ceramic SMD cap across diode leads.

Kinda hard to heat-shrink the leads then.

 

[Kizdawg]

I dont even know what the mF stands for! lol:shhh:

 

[tsteele93]

I dont even know what the mF stands for! lol:shhh:

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