Silly electronics question.

[DrummerMan]

Dumb question: if a circuit calls for a 470pF ceramic capacitor and I don't have any, can I do something with the MANY other values I have to give me the same result? Something in parallel?

This isn't for a critical application. I'm working on electrical engineering basics with my son for homeschool. I have a few assortment kits of parts but of course don't have what I need for this thing we're putting together now. Not being able to run out somewhere to pick small parts up and not wanting to pay a big shipping fee and wait a week and a half for DigiKey, I was wondering if i could make due with other values (like I do when I run resistors in series).

Of course this kind of thing is good to know regardless. Any thoughts appreciated. Thanks!

[Scodiddly]

You'd increase the capacitance by putting them in parallel, and decrease the capacitance by putting them in series. Resistors work the opposite way. Simple formulas to figuring out the answer if it's more complicated than 1+1=2.

Ever wonder why you keep seeing values like 470, 220, etc? Used to be more like 500, 250 and so on. But the values based on 1, 2.2, 4.7, 6.8 and so on are used because you can add them up to produce a lot of different values.

[DrummerMan]

You'd increase the capacitance by putting them in parallel, and decrease the capacitance by putting them in series. Resistors work the opposite way. Simple formulas to figuring out the answer if it's more complicated than 1+1=2.

Ever wonder why you keep seeing values like 470, 220, etc? Used to be more like 500, 250 and so on. But the values based on 1, 2.2, 4.7, 6.8 and so on are used because you can add them up to produce a lot of different values.

Awesome. I thought it was something like that but I was having a hard time confirming that with my internet research. Thanks a lot!

[The Scum]

This isn't for a critical application.

Then do whatever is close & convenient. Got a 500 pf? You'll be fine. Or two 220's in parallel...or 5 x 100's...or two 1nF's in series...

(the tolerances on the cheap "lentil bean" caps are often +/` 20% anyways...so you'll be in the neighborhood, if not exact.)

[DrummerMan]

Ok, one more question about reducing. Let's say you have 2 100k resistors in parallel. Would it be 100k - 100k, essentially canceling them out and saying there's no resistance?

Likewise with, say, 2 470pF caps in series?

I'm having a hard time wrapping my brain around why either of those works.

[ulriggribbons]

Here's a couple links to help:

https://www.allaboutcircuits.com/tools/ ... alculator/

https://www.omnicalculator.com/physics/ ... -capacitor

[DrummerMan]

Here's a couple links to help:

https://www.allaboutcircuits.com/tools/ ... alculator/

https://www.omnicalculator.com/physics/ ... -capacitor

Beautiful. Thanks!

[Scodiddly]

Ok, one more question about reducing. Let's say you have 2 100k resistors in parallel. Would it be 100k - 100k, essentially canceling them out and saying there's no resistance?

Simply put, half the current goes through one resistor and half goes through the other. So it's 100k / 2 = 50k.

Likewise with, say, 2 470pF caps in series?

With two same-value caps in series it would be 470pF / 2 = 235pF. The signal has to push its way through both caps, doubling the effect. In audio circuits a capacitor lets highs through the but blocks lows, and the more capacitance the lower the frequencies that can get through. So a smaller capacitor value increases the effect of blocking lows.

[DrummerMan]

Thanks for the help! Just for fun, here's what my 10 year old was working on and we finished today: single chip electronic dice! (You can see the parallel capacitors in the middle...)

https://youtu.be/talrEGehNbY