Flat pin plug

[Parm]

I’ve got this type of plug on a 4v led light

ive lost the power supply but have a spare one I can splice in if I cut the plug off, but how do I identify positive and negative?

 

[James1979]

Is there anything on the light? or tracer on one of the wires? Stupid question as you’ve looked I suppose

 

[mtt.tr]

Only way would be by looking at the circuitry

 

[MetalMonkey]

Looks like an old fashioned DIN speaker connector.

I believe the convention was the round pin was +ve and the blade -ve.
However that obviously isn't a big deal on a speaker, and doesn't mean they have wired it that way around in this application.

Easiest option is put a meter on it.
Or just wire it up and try it - if it is directly to the LED and no other components and the voltage is low it shouldn't cause any damage if you wire it backwards.

 

[James1979]

Looks like an old fashioned DIN speaker connector.

I believe the convention was the round pin was +ve and the blade -ve.
However that obviously isn't a big deal on a speaker, and doesn't mean they have wired it that way around in this application.

Easiest option is put a meter on it.
Or just wire it up and try it - if it is directly to the LED and no other components and the voltage is low it shouldn't cause any damage if you wire it backwards.

I think you’re right about the convention but if it’s from China it can be anything. I screwed a battery pack up the other day by assuming it would be centre positive as conventional. That was from China.

 

[Barking Mat]

It will work or not, if it doesnt reverse thé polarity.

 

[mtt.tr]

It will work or not, if it doesnt reverse thé polarity.

And dead leds

 

[TechnicAl]

your tongue

 

[skotl]

Do you have a multimeter with a diode setting? Just put it across the connector and it should read open in one direction and a forward voltage (0.6v normally) in the other. When it's reading forward voltage then the +ve lead on your meter is +ve from the power supply.

(if I didn't have a multimeter I'd just try it with a 3v supply - two batteries in series - if it's the wrong polarity it's extremely unlikely to blow the LEDs)

 

[Barking Mat]

And dead leds

Reversing the polarity won't kill leds.

In my experience.

 

[Pete.]

And dead leds

Doubtful at 4v. The function of a diode is to block electric flow one way and allow it the other after all.

 

[Barking Mat]

your tongue

what does that mean?

 

[mtt.tr]

Reversing the polarity won't kill leds.

In my experience.

That depends on led reverse voltage and circuit design

 

[mtt.tr]

Ah ha


I completely missed the 4v yes most typical leds are about 5v vr that will teach me for being illiterate.

 

[Barking Mat]

That depends on led reverse voltage and circuit design

I thought we were discussing simple light emitting diodes.

 

[mtt.tr]

I thought we were discussing simple light emitting diodes.

I am this is a typical datasheet chart for an led, i missed the "4v" in parms initial post

 

[TechnicAl]

what does that mean?

i was joking........not very well

 

[brightspark]

just wont work with reversed polarity and wont damage it if wrong, sometimes 2 core white or black cable has a thin stripe down the positive

 

[mtt.tr]

Next question, is it just leds or does it contain circuitry within?

 

[Barking Mat]

Does it vibrate?