RODALCO

230 Volts LED night light project.

Here is an addition to the popular LED indicator lights.

I have made some LED lamps as well for 230 Volts. I used an old base from a discarded compact fluorescent lamp. It got the B22 socket and has a wider base which is excellent for the LED project. I use them as night lights in my house so I don’t have to switch lights on and wake myself up too much when going to the loo.

Of course an Edison E27 base can be used as well and for 110 Volts use 2 *8k2 or 10 k Ohms resistors in series.

3552 The B 22 base with 4 * 8k2 ohms , 1 Watt resistors and the 1 N4007 diode.

3553 Side view of B 22 base.

3554 9 LED’s glued with araldite to a transparant pvc base. (8 blue, 1 green).

3559 Section of LED’s under test. I find it very handy to test for correct polarity when a string of LED’s is soldered. It saves a lot of messing about later on when things don’t work when a LED is put in the wrong way around. I use a 12 Volt power supply limited to 10 mA, so I can’t blow up any LED’s.

3561 Test run at 230 Volts. Current is only 3.17 mA.

3565 LED lamp going in my lounge.

3566 LED lamp from different angle.

Regards, Raymond

Keen to hear ideas or see photo’s from other forum members who have built some LED lamps.

Attached Images

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	DSC03553.JPG (111.3 KB, 31 views)
	DSC03554.JPG (119.2 KB, 37 views)
	DSC03559.JPG (125.0 KB, 35 views)
	DSC03561.JPG (151.8 KB, 39 views)
	DSC03565.JPG (119.3 KB, 23 views)
	DSC03566.JPG (113.9 KB, 27 views)

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Hero999

Why use blue, it destroys your night vision?

Use red because the rods don't respond to it which enables you to stay dark adapted.

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RODALCO

Thanks for the tip Hero999. I like blue that's why it choose it.

You got a good point there, thanks.

Any colour led may be used, it's up to the user.

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student1616

good to see u back in LED action "RODALCO"
and thanks for the details.

during these days i come across some data where they said one can drive the LED much brighter using PWM method.
say 20ma is the suitable current for LED,if we drive them at 50ma it will generate more brightness along with lot of heat eventually it will burn out.
in PWM mode the current will keep switching.giving the time for LED to cool down.
have u done any research over this LED driving method.
i know iam going from 220v AC to PWM dc(off topic),but its related to to LED

I²R

Driving an LED past peak IsubF works just fine; you need only ensure the average delivered power doesn't exceed the maximum rated power dissipation of the device over a very short period of time. Note that overdriving an LED in this manner will likely cause its peak wavelength emission to shift up slightly. This characteristic has been employed deliberately, for example to get blue LEDs to emit in the UV.

Hero999

The PWM thing only works on some red and infrared LEDs, modern blue LEDs actually tend to be more efficient at lower currents.

The UV trick only works on a specific kind of blue LED that's no longer made.

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student1616

so can a 555 based PWM generator do that job?
http://www.reuk.co.uk/LED-Dimmer-Circuit.htm
this circuit is ment for LED dimming,but can we use it for over driving.
and say if i use good heat sink along with LED's,how much is the possibility for over driving.

Hero999

A 555 timer PWM dimmer isn't really compatable with this kind of power supply as it is at the moment. To make it work with a 555 you need to add a zener diode and a filter capacitor to give a stable DC power supply.

I wouldn't bother as I don't see the point in PWM unless you do want to change the brightness.

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student1616

why iam running behind this PWM-over driving led is,
i saw a product made by the local company in my area.they make LED lights.they are so bright and nice that i amazed.i did some inquiry abt that product.and came to know that they are using same LED's that iam using for my experiments.my friend,(who work in that company) said that they are using some sort of driving circuit(involving flat heat sinks) to avoid the more number of LEDs to get more brightness.
then i had this PWM'ing in my mind.

I²R

Not quite true. Nearly any LED can be driven to a higher luminance than designed for by PWM overdriving; although, as you noted, the efficiency may suffer as a result. Whether the increase in light output is visually noticeable or not depends on the LED and its emitted spectrum. And all LEDs exhibit some degree of spectral shift when driven at other than nominal current (both under- and over-driving). Whether the shift is towards the blue or red depends not only on the relative magnitude of the driving current, but also on the specific chemistry. Many LEDs will blueshift when overdriven, but some will redshift instead. There isn't much need anymore to drive a blue LED to emit UV, what with the ready availability of UV LEDs with peak emissions as low as 360 nm (and even lower if you're willing to pay for it.) If you can manage to wade through the technical jargon, the following article addresses the spectrum shift issue:

http://www.lrc.rpi.edu/programs/soli...PIE6337-17.pdf

Hero999

I'm not disputing that LEDs will give more light when pulsed at higher currents. It's just not worth if because the efficiency invariably suffers and the response of the human eye acts like a low pass filter so it won't make any difference to the overall brightness. For example PWMing an LED at 50% duty cycle with double the current might make it twice as bright but it won't look any brighter.

PWMing is only worth it if the LED does work better at higher currents or it is used for transmitting information as the range may more than double without using any extra power.

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audioguru

I agree with Hero.
My Ultrabright LED chaser projects use PWM to dim the LEDs. When the duty-cyle is 20% and less then the LEDs are dimmed. When the duty-cycle is 1/1000 then they are very dim. The peak current is exactly as high as when they are bright.

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I²R

Uh, yes, it would be. PWM doesn't change the applied voltage during the "on" time and therefor doesn't affect the current draw.