120volt 4 LED night light

[ben7]

I made a circuit for a 120volt AC night light. Hope you like
https://www.electro-tech-online.com/content/345-120volt-led-night-light.html

Parts:
1x 1N4007
4x white leds
1x 100uf-220uf 25volt capacitor
1x 9.1K 5 watt resistor
1x 1Meg 1/2 watt resistor

When I took the picture of the circuit working, I only had two 4.7K 5watt resistors on hand.
I had also written on the circuit that C1 is optional because some people don't see flickering.

120volts IS Dangerous!!! Be CAREFUL!!!

 

[ben7]

The 120volts is only rectified on one cycle so the 9.1K resistor dissipates around 3.5 watts instead of nearly 10 watts!

The 1Meg resistor eliminates [most] voltage spikes.

You can use a 100 to 220uF cap for C1.

When you first test it, you should run it on an isolation transformer.

 

[alex69]

Nice job. Unfortunately in my country we use 220VAC. so I can't try it.
Alex

 

[ben7]

You might be able to double the resistor value though, I'm not sure, I never play with 220volts, only 120volts.

 

[ronsimpson]

There has been plenty of talk on this forum about capacitor divider power supplies (LED lights). They use a large capacitor and no power resistor.

 

[ben7]

There has been plenty of talk on this forum about capacitor divider power supplies (LED lights). They use a large capacitor and no power resistor.

I don't think you can replace the resistor with a capacitor in this circuit.
Also, those capacitors can get quite big too!

 

[alex69]

You might be able to double the resistor value though, I'm not sure, I never play with 220volts, only 120volts.

Ok. I'll start experiments. If someone hear an explosion....

 

[RODALCO]

LED nite light

Be sure to use some safety goggles during testing.

The leds don't always have to run at 20 mA's. Often at 10 or 15 mA they are just as bright and saves in heating of the power resistor.

I have a couple of clips of 120 and 240 Volts led lamps on my YouTube channel which show how I make them.

The more led's in series the less voltage drop across the resistor (or Cap)

 

[ben7]

Be sure to use some safety goggles during testing.

The leds don't always have to run at 20 mA's. Often at 10 or 15 mA they are just as bright and saves in heating of the power resistor.

I have a couple of clips of 120 and 240 Volts led lamps on my YouTube channel which show how I make them.

The more led's in series the less voltage drop across the resistor (or Cap)

Yes rodalco. I have played with this circuit a lot.

When you run leds for a while at thier max current, thier mcd rating drops over time. Leds will still be bright when ran for a long time at a lower current.

 

[ben7]

Ok. I'll start experiments. If someone hear an explosion....

he he he

 

[ben7]

V2.0

Circuit V2.0.

It uses a capacitor to replace the 5watt 9.1K resistor in the original circuit.
The capacitor takes up more space than the resistor but the capacitor has an advantage-it does not dissipate any heat.

This circuit still is designed for 120v and I've tested it too.
Turn on time is about 1/6th of a second.

If you leave out R2, your sensitive leds will be led to thier doom after a few on/off cycles.

 

[KeepItSimpleStupid]

I like capturing "Magic Smoke". I use it for other non-woring projects.

 

[RCinFLA]

Your LED current is very low. Series dropping cap should be about 0.5 uF for 20 mA's on LED's

 

[ben7]

Your LED current is very low. Series dropping cap should be about 0.5 uF for 20 mA's on LED's

Leds don't need 20 mA, when you run them on such a high current, they dim over time, and they run hot decreasing their lifetime even more.

 

[USMC_SPIKE]

Hi, maybe you guys have this schematic or know if it.

I'm looking for a 2 diode circuit to run off 120 VAC which drives 2 - 6 LEDs.

I found a circuit and bookmarked it but now it is no where to be found.

I think the circuit was similar to the V1 schemati here but with an extra diode and resistor.

It is not the v2 shown here. is v2 a full wave bridge?

I'm looking to replace a 120 watt bulb that craps out almost instantly to do being banged
around. I'll then solder this to the mount after building it and install it.

I don't want the blinking so I recall there is a simple way to have it illuminate for
both cycles of the 120 VAC.

Please advise. ; )

Spike

 

[Reloadron]

I'm looking to replace a 120 watt bulb that craps out almost instantly to do being banged
around. I'll then solder this to the mount after building it and install it.

Replacing a 120 watt incandescent bulb won't be easy as a general small night light. However this link will get you to some 120 vac (or 240 vac) LED circuits.

Also, when using alternate half cycles of 50 or 60 Hz. AC you will not see the blink. The human eye isn't that quick.

Semper Fi
Ron

 

[ronsimpson]

I do not agree with you. The center of the eye can not see 50hz--yes. The edge of your vision can see 60 hz. Computer monitors have increased their refresh rate over the years. It is typical to see >70hz refresh rate on computer monitors. One of my projects, we are PWM the light and found if the human head moves fast or the light source moved the eye saw a string of flashes.

Also, when using alternate half cycles of 50 or 60 Hz. AC you will not see the blink. The human eye isn't that quick.

Semper Fi
Ron

 

[Reloadron]

I do not agree with you. The center of the eye can not see 50hz--yes. The edge of your vision can see 60 hz. Computer monitors have increased their refresh rate over the years. It is typical to see >70hz refresh rate on computer monitors. One of my projects, we are PWM the light and found if the human head moves fast or the light source moved the eye saw a string of flashes.

OK, I stand corrected. I can't notice the difference or flicker at 60 Hz. but apparently some people can.

It is a fact that all LED lights naturally flicker at a rate of approximately 60 Hz per second. Even though that is an extremely fast rate of speed, there are some individuals who can actually detect the flickering at that rate. This is known as a half wave, also called non-rectified light. This type of light is common to various Christmas LED light sets and may be more easily detected if the lights or the individual are moving. Unfortunately, this flickering in non-rectified lights is a common complaint of consumers in regards to some inexpensive Christmas lights.

Try a few things and see what you get. However, replacing a 120 watt incandescent bulb with a small handful of LEDs will be a task.

Ron

 

[gilmanli]

Hi ben 7,
For safity I suggest you first calculate the voltage drop at each components ( LEDS,resister,capacitor ) then selcet the suitable components ( watt at resisters,voltage at capacitor ) such that we have a confident say the circuitry is safity.

B.R.
Gilman Li.

 

[Diver300]

I do not agree with you. The center of the eye can not see 50hz--yes. The edge of your vision can see 60 hz. Computer monitors have increased their refresh rate over the years. It is typical to see >70hz refresh rate on computer monitors. One of my projects, we are PWM the light and found if the human head moves fast or the light source moved the eye saw a string of flashes.

I find 100 Hz flashing intensely distracting, if the mark-space ratio is small. Some car tail lights are like that, 'cos some idiot read that the human frequency limit is about 50 Hz, which it is when nothing is moving. It's just a pity that cars move, and that I move my eyes to look at different things.

I have managed to detect the flashing of an LED at around 5 kHz. That does have to be in just the right conditions, and I can't do that all the time, even if I try. However I find 1 kHz flashing quite easy to detect if it is a small light source and the background is dark.