School Me About These Caps

ScumBum

Well-known member
Joined
Jun 18, 2008
Messages
5,240
Reaction score
395
Location
California
My DK Jr. board has some broken caps that need replacing and I don't know the value or type to order from bob .


016.jpg


019.jpg


I know this is an electrolytic capacitor , but the leads are on top and bottom instead of at one end .

004-1.jpg
 
I just learned some of this today when I was at the electronics store picking up some caps.

The bottom cap is an axial cap (legs coming out from each side). Typically what you'd want is radial caps (legs coming out the same side) but in this case it's axial.
 
Nice page here, I think both your first and second pictures are referred to in the page, and the green one has the value printed on the board (0.1uF): http://www.piclist.com/images/www/hobby_elec/e_capa.htm

Second picture is 0.01 µF ceramic capacitor, again shown on that page.

Your third picture is an axial capacitor, values printed on it, 100uF, 16V (other type is radial, both leads on one end).
 
Last edited:
so is the green one a Polypropylene or Polyester Film Capacitor ?

Whats the 1H on the green one and 27 on the ceramic capacitor about ?
 
The green one is likely polyester, cheap and abundant at the time. Polypropylene has higher tolerance. If you can't find polyester, you can use polypropylene.

Other numbers are usually max voltages, so with the ceramic, it has a max rating of 27 volts.

The 1H I know from expereince means 50v (google "1H 50v", and you will find some references). This pdf file has a table of codes and values: http://www.ibselectronics.com/ibs/cmpnts/rgaco/catalog/B/CeramicCCB2_16.pdf

There are a lot of resources online, but I've never found one definitive page, so here's some further reading if you're interested:

http://www.sentex.net/~mec1995/gadgets/caps/caps.html
http://www.mikesarcade.com/arcade/components.html
 
Last edited:
The green one is a mylar (a.k.a. polyester or metal film). You can substitute a ceramic disc style for it if desired. Value is .1 uf @ 50 volts

The second one is a ceramic disc. Value is .01 uf @ 50 volts. You can substitute a mylar/polyester/metal film style if desired.

The third one is an axial lead electrolytic. 100 uf @ 16 volts. A higher voltage one can be substituted.

You can buy all of these at Radio Shack. The following will work perfectly fine and here are the numbers:

# 272-1069 Mylar (metal film polyester) Capacitor, .1 uf @ 50 volts

# 272-1065 Mylar (metal film polyester) Capacitor, .01 uf @ 50 volts

# 272-1016 Axial lead electrolytic capacitor, 100 uf @ 35 volts
 
The green one is a mylar (a.k.a. polyester or metal film). You can substitute a ceramic disc style for it if desired. Value is .1 uf @ 50 volts

The second one is a ceramic disc. Value is .01 uf @ 50 volts. You can substitute a mylar/polyester/metal film style if desired.

The third one is an axial lead electrolytic. 100 uf @ 16 volts. A higher voltage one can be substituted.

You can buy all of these at Radio Shack. The following will work perfectly fine and here are the numbers:

# 272-1069 Mylar (metal film polyester) Capacitor, .1 uf @ 50 volts

# 272-1065 Mylar (metal film polyester) Capacitor, .01 uf @ 50 volts

# 272-1016 Axial lead electrolytic capacitor, 100 uf @ 35 volts

Thanks alot Ken ! Going and picking these up right now .
 
The green one is a mylar (a.k.a. polyester or metal film). You can substitute a ceramic disc style for it if desired. Value is .1 uf @ 50 volts

You can't always sub a ceramic for a polyester or metal film.
Ceramics often have a tolerance of +80%/-20%.
Polyesters typically have a tolerance of +/-10% and often 5%.
Poly's are often used in timing circuits due to their tighter tolerance.
Going from the first picture - that cap is directly between two timers -- two 74LS123's. Most probably it is part of a timing circuit. I would not use a ceramic in that instance.

The RatShack part numbers given are fine, though.

To answer the question regarding the "1H"
Part is marked 104K / 1H. 104 = 0.1uF, K = 10%, 1H = 50V.
 
You can't always sub a ceramic for a polyester or metal film.
Ceramics often have a tolerance of +80%/-20%.
Polyesters typically have a tolerance of +/-10% and often 5%.
Poly's are often used in timing circuits due to their tighter tolerance.
Going from the first picture - that cap is directly between two timers -- two 74LS123's. Most probably it is part of a timing circuit. I would not use a ceramic in that instance.

The RatShack part numbers given are fine, though.

To answer the question regarding the "1H"
Part is marked 104K / 1H. 104 = 0.1uF, K = 10%, 1H = 50V.

I picked up ceramic instead . I guess I shouldn't use them ?
 
I picked up ceramic instead . I guess I shouldn't use them ?

Depends ... most of the ceramic caps had wild tolerances and were worthless in timing circuits. But - you *can* get caps as close as +/-5%. Just depends on exactly which one you got.
The ceramics with the tight tolerances tended to cost more than the poly caps with tight tolerances wich is one reason why the poly caps were often used.
 
I just went to radio shack and picked up exactly what ken suggested , took 2 minutes because ken provided the catalog # . I'm not gonna use the ceramic caps .
 
Back
Top Bottom