Warning

 

Close

Confirm Action

Are you sure you wish to do this?

Confirm Cancel
Member Login
Site Notices
Posted: 2/7/2006 6:38:05 PM EDT
I am trying to build a Code Practice Oscillator to learn morse code and got a question.

On an electrolytic capacitor is the polarity mark with the neg (-) only?
On one side it looks like a (-) but the wrap is a little distorted and can not tell. I can not see any Markings for pos (+) at all.

73
Bobwrench
Link Posted: 2/7/2006 6:41:38 PM EDT
[Last Edit: 2/7/2006 6:42:08 PM EDT by SWS]
Small electrolytics are usually marked only with a (-). Big, computer grade electrolytics are usually marked with both (+) and (-).

IIRC, tantalums are usually marked with a dot to denote (+).
Link Posted: 2/7/2006 6:46:35 PM EDT

Originally Posted By SWS:
Small electrolytics are usually marked only with a (-). Big, computer grade electrolytics are usually marked with both (+) and (-).

IIRC, tantalums are usually marked with a dot to denote (+).



Thanks that maybe why it doesn.t work. I'll go back and see if I need to make the change. I could not get it to work and had to put it down for a while. I checked the circut diagram and it seems right , the olny question I had was the polarity.

Bobwrench
Link Posted: 2/7/2006 6:47:16 PM EDT
and some are marked with a arrow like pattern pointing to the pos ( showing current flow direction )
Link Posted: 2/7/2006 6:49:07 PM EDT
Usually only the neg is marked on an electrolytic... Is there any reason you are stuck on an electrolytic? Nonpolarized caps are superior wrt to accuracy and hf.
Link Posted: 2/7/2006 6:58:18 PM EDT

Originally Posted By bobwrench:
that maybe why it doesn.t work.



I've seen electrolytics and tantalums that were mis-installed and the circuit still worked. In fact, a few worked for a long period of time as long as they weren't run near their max operating voltage.

In a low-voltage, low-stress audio oscillator circuit, I'll bet something else is wrong.
Link Posted: 2/7/2006 7:11:42 PM EDT

Originally Posted By SWS:

Originally Posted By bobwrench:
that maybe why it doesn.t work.



I've seen electrolytics and tantalums that were mis-installed and the circuit still worked. In fact, a few worked for a long period of time as long as they weren't run near their max operating voltage.

In a low-voltage, low-stress audio oscillator circuit, I'll bet something else is wrong.



Yea...and I've seen low-E high current DC power supply caps EXPLODE like a rifle shot if they are installed backwards too. The damage to the supply was most impressive.
Link Posted: 2/7/2006 7:19:26 PM EDT
Yup. The input filter caps on a switching power supply will blow up real good. They'll spray paper, plastic and foul-smelling oil all over the place.
Link Posted: 2/7/2006 8:05:21 PM EDT
[Last Edit: 2/7/2006 8:06:15 PM EDT by A_Free_Man]

Originally Posted By Engineer:
Usually only the neg is marked on an electrolytic... Is there any reason you are stuck on an electrolytic? Nonpolarized caps are superior wrt to accuracy and hf.




This is a code practice oscillator, not hi fi gear. Aluminum electrolytics are a tiny fraction of the cost and size of various non-polarized film caps. It would be rather silly to use anything else in such a circuit.

(Ed, I am my own spelling Nazi)
Top Top