How to drive 50 LEDs on 220V AC without the use of a transformer?

[me_guitarist]

how to drive 50 LEDs on 220V AC without the use of transformer?

 

[Jack// ani]

led in ac

put the LEDs in series....assuming that you have blue with led (3v drop)....50leds will sum up to 150v, to drop rest 220 - 150v = 70v put a series resistor. led will glow fine...if current is anywhere between 8mA-12mA. so now i think its easy for you to calculate value of series..

good luck

 

[nguyennam]

led by ac

Plus, for creating 150V, you can use 1 diode to make it a half-cycle rectifier, and in parallel with the LED "chain", you place another diode in reversed way to protect the LEDs from the inversed voltage.

nguyennam

 

[IanP]

led ac source

LEDs have low reverse voltage, so much safer is to go through a rectifier, and as AC "resistor" use a high-voltage capacitor .. see picture blow ..
Probably 10 chains of 5 LEDs connected in parallel would be a good option ..

Regards,
IanP

 

[trieuvan]

led with ac

Plus, for creating 150V, you can use 1 diode to make it a half-cycle rectifier, and in parallel with the LED "chain", you place another diode in reversed way to protect the LEDs from the inversed voltage.

nguyennam

And the one more : you can calculate the resistant of the capacitor as Rc= ...fC.

 

[on1aag]

ac leds

Hi Me_guitarist,

Here's an idea how things could be done, I only had eight blue leds of
9000 mcd at 20 mA. The circuit is very simple, the 330 nF capacitor
limits the current through the circuit to about 22 mA. The voltage drop
over the 220 Ω resistor was 5 V and the ripple was 300 mV pp.
The 100 Ω resistor, the 55 V VDR and the 220 µF capacitor play also a
significant role in the circuit. They limit the inrush current of the
leds to a safe value in order not to damage them at turn-on. During
normal operation the 55 V VDR doesn't do anything at all.

The 100 Ω fusable resistor, far left, will act as a fuse without bursting
into a fireball. Next to that is the 330 nF / 250 Vac / X2 class capacitor.
Check local safety regulations and use an approved type of capacitor
constructed from flame retardent materials. A 400 Vdc capacitor is not
designed to withstand 230 Vac and is most certainly not approved. The
12 MΩ bleeder resistor is also special, it's a high voltage type. This one
is a 500 mW type that can withstand 5 kV (dc + peak ac), a 250 mW type
is also ok 1600 V (dc + peak ac).

And last but not least use a safety transformer to isolate you from the mains.
The best way to learn is by experience, but that doesn't apply here !

on1aag.

 

[Jack// ani]

how to use led in ac

yes....transformer is after all the best option, but not compact one!!

thanks IanP and nguyennam...for reminding me about diode, I do remember...once I smoked my leds due high reverse voltage. especially its true in case of blue/white leds which have very low reverse breakdown voltage...although red led work fine without any diode.

 

[me_guitarist]

led em ac

Thanks all U guys for the opions.I'll try to work on it and post back the result.

Added after 44 minutes:

Dear IanP,
sorry for my dump question coz am just a beginer in electronics.
whats the 470nF capacitor voltage should i use?

 

[mmike]

led to ac

Hi

I would like to know the selection criteria for 12M 330nF, is there any design calculation , or just by thumb rule applied for the selection of resistor cap ..


Reply in this regard will be appreciated...

Thanks

 

[klug]

led on ac transformer

I would like to know the selection criteria for 12M 330nF

It is simple: think of C as of R.

Xc=1/(2\[\pi\]fC) , where:
Xc - reactive resistance of capacitor (Ohm),
f - frequency (Hz).

so, if you calculate, you will get 10K resistance on 50Hz for 330nF capacitor.

12M resistor is added to discharge capacitor after device switching off. You can take 10-20M without big difference.

 

[cbarbara]

how to make led work in a.c

if you calculate, you will get 10K resistance on 50Hz for 330nF capacitor.

Explanation is very good however there is no 10K resistor in the circuit I could find...

I have one more doubt of using 220 uF / 63V DC capacitor.. It may burst at a prolonged usage .. becuase DC voltage after the bridge will be 230 * sqrt ( 2 ) around 300 + VDc 63V rating of the capcitor will be insufficient ....

Comment from any one , will be appreciated...

 

[bigaussie]

led on ac

connect LEDs in series with a diode for protection & 325-153v/80ma=resistor value.

 

[Eugen_E]

ac white led work problem

 

[VSMVDD]

led 220v ac diode

you would prob be better to adopt a resistor array transfer function
in terms of resistive reactance
and loose couple it to ac sources using a 50 /60 hz pick up coil of sorts

bind it to the led array
bank switched at a v peek but

using arrays of resistor values and made up reactive leds
set to yield at the given sine ratio against depletion
using a referance ttl 1 hz width per led

so back to the 50 ms percistance of vision

banking 25 leds would also
negate the need for rectifications

so 25X2 bi phasial sine sq/2 strobe driven is better

using a person or a ground plane source ....

a reactive led antenna of sorts ... dependant on its strobing
it can act as an ac arrow
a ultra low power light bar
a bar graph
a current meter
a moving sign

just by adjusting its clock and led sin slew
and hanging it near a power wire
or making a low power mechanical sine wave

to make a wind up lamp

you are all fools √ lol....<<

:idea: :!:

 

[me_guitarist]

white led ac capacitor circuits

Can this circuit work on 50 LEDs?How?
**broken link removed**

Added after 1 minutes:

 

[Medtronic]

is series leds a good option

Hi To All

Good Question and good answers

Regards