100nf capacitor polarity check

[metiz]

Hello everyone

me and my friend are working on a mk160 circuit boar. it's a remote controll through cellular phone. the board is all but done but we're stuck on 2 capacitors and a ldr.

there's no markings on the capacitors or the ldr to determine polarity. How can I do this without testing equipement?

they're 100nf capacitors and there's "104." written across it wich could be used to determine + and -

Can anyone help with this?

oh yeah, the negative pole always needs to be pointed towards the large conductive path that covers most of the pcb right?

Thanks

 

[betwixt]

Normally LDRs and capacitors as small as 100nF do not have a 'polarity', they work equally well either way around.

On most boards, the largest copper area is 'ground' and it is usually the negative side of the supply. There are exceptions - but they are rare.

Brian.

 

[pranam77]

LDR's are just resistors and 100NF will have no polarity. You can connect them iether way on the circuit. But when it comes to Electrolytic capacitors, you'll find a - mark for the negetive terminal or the negetive terminal will be shorter than the posetive.
Cheers

 

[karesz]

Hi,
"100nF will have no polarity" is true only nowadays, by modern capacitors, then some older types as Tantalums(they oesexist from 100nF todays too) & such earlier ceramics with very HighDiel.Const. versions have had in a direction (also polarised) better worked (or some type would be "selfpolarized" after longer working time too)...
They have had (mostly) a "shorter line" marking to one contact too as by diode Cathode...
K.

 

[metiz]

Hi

Thanks for the reply everyone!

We've been messing around with those things for more then an hour but with info provided the board is now complete!