I found this circuit diagram that someone had posted.

I always thought that symbol for the capacitors was a polarized capacitor e.g. an electrolytic. Is anyone savy enough to tell me if they all are or just c1 and c2? What is .01? Is that pf or uf? Also .o1 pico or micro farad sounds like a small electrolytic.

 

I found this circuit diagram that someone had posted.

I always thought that symbol for the capacitors was a polarized capacitor e.g. an electrolytic. Is anyone savvy enough to tell me if they all are or just c1 and c2? What is .01? Is that pf or uf? Also .o1 pico or micro farad sounds like a small electrolytic.

Since all caps are 0.01 (I'm assuming they're in µF, which are the most common units) their capacitance is way too small to be electrolytic, and I very much doubt they're tantalum either. Therefore they must be disk ceramic, which are unpolarized. Lots of people draw them as "-|(-" even though traditionally an unpolarized cap is drawn as "-||-" ... but since the designer has omitted the "+" sign, you can be almost certain that they're unpolarized... Anyway, that looks a lot like a Forrest Mims circuit to me!.

 

that image is from the old "Engineering Notebooks" by Forrest Mims. Yes, all capacitors were drawn that way when the book was written.

 

They're non-polarized. You can bet that those caps are going to see both polarities, so they better be non-polarized.

Electronic symbols have never been rock-solid-engraved-in-stone standardized, so you often have to infer what was meant. Sad, but that's just the way it is.

 

I still draw non-polar caps that way.

Polarized caps get the + sign *always* on the non-curved side.

It's clear to me though I admit there could be confusion. Old habbits die hard.

 

0.01μF non-polarized capacitors

 

back in the old days, the curved plate of a cap was the outside foil on non polarized caps helpfull when you were using paper caps as bypass or coupling caps, to cut down hum or noise pickup. yes, that is a .01 micro farad non polarized cap.

 

When I was first introduced to industrial controls in 1965, the individual training me laid out a large set of drawings he referred to as the "prints". Opening a page and pointing to a -||- symbol, he asked if I knew what that was. "It looks like a capacitor, but I've never seen them connected like that", I said. After a slight chuckle, he explained that those were representing normally open relay contacts and the drawing was known as a ladder diagram. He turned a couple of pages and was able to show that capacitors were drawn as -|(-.

 

Anyway, that looks a lot like a Forrest Mims circuit to me!.

It is. I have that booklet.

 

When I was first introduced to industrial controls in 1965, the individual training me laid out a large set of drawings he referred to as the "prints". Opening a page and pointing to a -||- symbol, he asked if I knew what that was. "It looks like a capacitor, but I've never seen them connected like that", I said. After a slight chuckle, he explained that those were representing normally open relay contacts and the drawing was known as a ladder diagram. He turned a couple of pages and was able to show that capacitors were drawn as -|(-.

Ahh, I forgot about that symbol, and I used it for about 10 years in a test department. They had wonderful racks of equipment with 200 or so switch points in a backplane very easy to access for any random job.

My boss was a buster and ran down my first design as "costing too much money" because I drew the backplane switches as traditional relays. Guessing he did not know the -||- symbol as a switch I used it on the next schematic I presented him.

My guess was correct, he did not understand what he was looking at. I don't know if his thinking was "caps are cheap" or "I just don't get his work" but he stopped questioning my designs after that.

 

When I was first introduced to industrial controls in 1965, the individual training me laid out a large set of drawings he referred to as the "prints". Opening a page and pointing to a -||- symbol, he asked if I knew what that was. "It looks like a capacitor, .

It depends on the environment you are working in, if working with electrical schematics or PLC prints, then you expect the -||- to be a N.O. contact, and capacitors, if present should be labeled as such.
I agree with Alfcliff, I have always regarded the -|(- as a polarized capacitor as far as the ( side being connected to chassis in the case of decoupling capacitors etc, but now you will find all kinds of symbol charts that show them as being electrolytic.
Max.