Strip LEDs: Series or parallel

[OldNick]

I assumed that the 3 LEDs per mini-section are in series. However, I was using a dimmer on one and reading the output voltage of the dimmer showed 5.2V just before extinguishment of the LEDs. I may be making a twit of myself, but how do 3 series LEDs keep going down to 5.2 volts total?Thanks for any help

 

[Changchung]

This happen with the groups of leds connect in serie, you cant dimmer them


Sent from my phone with camera with flash and internet on it...

 

[SemiMan]

Wrong .... You can.

Was the driver you were using variable output voltage or pwm. Strips are normally dimmed with pwm drivers.

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[OldNick]

Wrong .... You can.

Was the driver you were using variable output voltage or pwm. Strips are normally dimmed with pwm drivers.

Sent from my Nexus 4 using Tapatalk 4 Beta

Yeah it is PWM. Now I do feel silly. The multimeter would read narrow pulses as low voltage. Thanks for jogging my ageing grey matter into activity

 

[OldNick]

This happen with the groups of leds connect in serie, you cant dimmer them


Sent from my phone with camera with flash and internet on it...

No I actually am dimming them. I was just puzzled how they kept going down to such a low voltage. However see my embassing results.

 

[Changchung]

I will try with mine PS tomorrow... Or I confuse with some AC leds bulbs???


Sent from my phone with camera with flash and internet on it...

 

[hellokitty[hk]]

I will try with mine PS tomorrow... Or I confuse with some AC leds bulbs???


Sent from my phone with camera with flash and internet on it...

Save your time it's just PWM, mystery solved.

 

[OldNick]

I will try with mine PS tomorrow... Or I confuse with some AC leds bulbs???
Sent from my phone with camera with flash and internet on it...

Yeah there are many LED bulbs that are not dimmable, because the driver circuit in them is already a constant current device, and also if you try to use PWM to dim them, it will just conflict with the output pulses of the driver already in the globe. Changing the voltage should not affect a decent constant current driver within its usage range, so you can't do that either.

These guys just have a 150 ohm resistor in series to limit current/drop voltage from "12v" to their operating volts. So the circuitry is as good as passive.