Led strip fade in and fade out

[zoxzox]

Hello everybody,
I would like to get my 1m led strip 12v to fade in/fade out when power supply is on/off. I have Mosfet IRLB8721, 100kohm resistor and 1000microfarad 16 volt capacitor. Can someone write me how to connect to those components to get fade on/fade out. Is it possible with these components at all? Is there any other simple diy way to make this fading?
Thanks

 

[zoxzox]

thanks i am watching now, but cant find PIR ? where is it in menu?

 

[BradtheRad]

thanks i am watching now, but cant find PIR ? where is it in menu?

To substitute for the PIR I made a stand-in using a SPDT switch. The spec sheet states the PIR turns On by outputting the supply voltage, however what is its Off state? I don't recall if its Off state goes to ground or high-impedance. You'll have to check what internal switch connections are inside your PIR. It affects how the timing capacitor charges and discharges.

Falstad's component list supports an LDR (light dependent resistor). Its resistance range is adjustable but it helps if we experiment with the simulated device. Click the slider to simulate changing light brightness.

 

[zoxzox]

@BradtheRad i got components and tried, the result is the same, pir turns led strip ON with fading effect, but after 30 seconds just turn led strip OFF without effect....

 

[FvM]

Impossible to get 5s fading out after turning off the supply without large energy storage. Need to start fade out first, the turn off supply power.

 

[KlausST]

We already know the power supply will stay ON.
The OP falsely told in his first post to switch OFF the power supply.
Now he wants to use a PIR sensor module connected at the power supply output.
At least this what I understood..

Klaus

 

[zoxzox]

Power supply
Pir
Led strip
It looks strane that you can get fade in but neot fade out effect... Pir is switch but this circuit is not discharged slowly... I think we are close like some component is missing to tell capacitor hey slowly discharge like you are slowly charging yourself...

Pir has positivr and negative inputs and positive and negative outputs
When pit cuts the power then led strip looks like there is no power supply like it is not conncted to power supply all the time

 

[FvM]

We already know the power supply will stay ON.

Thanks, didn't notice.
Control characteristic of the MOSFET circuit suggested above is inappropriate. You need either linear or even exponential I/t characteristic, doesn't work well by applying a RC filtered gate voltage to MOSFET. I would determine useful LED currents for sec 1, 2, 3 , 4 in an empirical test with variable power supply, then design a circuit that implements this I/t characteristic for fade in and out.

 

[zoxzox]

i do not understand what are you saying, but i hope you will tell me what to use and how instead of mosfet to get fade in/out effect

 

[D.A.(Tony)Stewart]

The best way to fade in/out at 12.5W is to use a PWM circuit that can be controlled from 0 to 100% in either a quasi-linear ( to the eye) or some exponential response controlled with low current.

I used a SPDT switch 0 to 5 and 5 to 0V. Your PIR can do that I trust with a pullup.
Then I used Vdd/2 for a reference to get a delay after the trigger followed by a slow ramp.
Since my design using the Falstad SIM is slow integrating here, I used 10 nF, you would use something like 1 uF ( if polar use Vrating >=50V so it can withstand 5% reverse voltage. If ceramic use Vr> 12V)

The idea with Falstad is that the mouse can do everything including move the part, change the passive parts' values, and click the middle of the switch.

 

[betwixt]

I think the underlying problem here is not knowing what kind of output the PIR produces.
Assuming this is a commercial light switching unit and not an actual PIR sensing component, there are two types:
1. triac output ones that directly pass/block the line connection to the lamp, these are unsuitable for this application.
2. relay output ones that mechanically (via the relay) switch the connection to the lamp. These can be adapted for this application.

PWM dimming is the ideal method but I suspect a little too complicated for zoxzox to build. The MOSFET solution doesn't give a linear rise and fall in apparent light level but it does change the brightness at low cost. If the PIR unit has a relay output, the first thing to check is that the relay contacts are isolated from the incoming line, a modification to the wiring may be necessary to ensure access to the contacts is safely available. If the common and NO and NC contacts are available things are easy and the rise in brightness and fall in brightness can be independently controlled.

Please show us what kind of IR sensing device you have, it makes a big difference to the best solution.

Brian.

 

[zoxzox]

First of all thank you @D.A.(Tony)Stewart for your message and effort, but @betwixt is right this is a space shuttle for me to build.
I have power supply 12v 60w, led strip 1 meter, which is 3w and pir... Here are the pics of pir

I think this small project can be useful to everybody

 

[KlausST]

Hi,

may I just repeat about your given informations:

LED:
post#1: 1m led strip 12v
post#5: current 1.2A
post#17: My led is 14.4w
post#31: led strip 1 meter, which is 3w
--> why do we get always different informations? Which value(s) are true?

Klaus

 

[D.A.(Tony)Stewart]

Hi,

may I just repeat about your given informations:

LED:
post#1: 1m led strip 12v
post#5: current 1.2A
post#17: My led is 14.4w
post#31: led strip 1 meter, which is 3w
--> why do we get always different informations? Which value(s) are true?

Klaus

Klaus; FWIW stripleds are rated per meter and come in 5m rolls.

--- Updated Oct 8, 2024 ---

First of all thank you @D.A.(Tony)Stewart for your message and effort, but @betwixt is right this is a space shuttle for me to build.
I have power supply 12v 60w, led strip 1 meter, which is 3w and pir... Here are the pics of pir

I think this small project can be useful to everybody

I never thought of an Op Amp as a Rocket Ship, but you are right and the Uno looks like a Satellite with solar panels.

For giggles, I removed the PWM so you can see how an "Analog Computer" works.
When the output is not limited to +5,0V it is a linear "integrator so it compares the inputs and changes the output to make them match in linear mode( 0 error).

"Look Ma, no Boot code"

https://tinyurl.com/ymsopt9c

See if you can toggle the switch.... without displacing it...

Added a little Green Martian

https://tinyurl.com/yqkbazyv

OK I'm off to play pickleball

https://tinyurl.com/yv2nmeh8

 

[KlausST]

Klaus; FWIW stripleds are rated per meter and come in 5m rolls.

Indeed useful information.

@ OP:
With informations like 1m, 1.2A, 14.4W .. you just confuse people (at least me).
If your application uses 1m only, then
--> just give the electrical informations: 12V, 0.24A. (Or whatever is true for your application)
That´s what counts.

Klaus

 

[betwixt]

Without involving NASA or doing space walks, that module can be used but only to control an external circuit. You have to keep the module powered up all the time and use it's output to provide power to charge the capacitor that in turn connects to the MOSFET. You can easily wire it to make the LEDs turn on slowly. Turning the LEDs off is slightly more complicated, there is a 'cheap and dirty' way by just adding a resistor across the capacitor but that also affects the turn on timing. Are you able to wire up an additional circuit using a few more components? None of them expensive and as a bonus you can use two controls, one to set the lighting up rate and one to set the dimming rate.

Before explaining, can you do a resistance (continuity) check to see if the '12V-' is directly connected to 'LED-' or if the '12V+' is directly connected to the 'LED+' pads. I'm trying to find out whether it breaks the + or - line to turn the LEDs on and off, quite likely the one that doesn't break is wired straight through.

Brian.

 

[D.A.(Tony)Stewart]

Hello everybody,
I would like to get my 1m led strip 12v to fade in/fade out when power supply is on/off. I have Mosfet IRLB8721, 100kohm resistor and 1000microfarad 16 volt capacitor. Can someone write me how to connect to those components to get fade on/fade out. Is it possible with these components at all? Is there any other simple diy way to make this fading?
Thanks

1. can you solder a few extra RC parts and a small NPN on a breadboard and add a 5W heatsink to the FET with an insulator?
2. is active low =0V ON?
3. what voltage is off? (from sensor)
4. verify your 1m pwr or current

 

[zoxzox]

I have led strip of 5m which is 12V, 1.2A and 14.4 W and 1m strip which is 12V, 0.24A and 2.88W....just the length of the strip is different, from now i will use only this 1m long to avoid confusion....idea is when i come to lobby pir turns on and light is ON with fade effect, and vice versa

@D.A.(Tony)Stewart bravo, bravo bravo, this is great for playing, but i do not have all these components but animation is amazing, slow fade in slow fade out...great, but you did it with 5v, is it possible with 12v with same component values? and this triangle with plus and minus inside, is that amplifier, can you give me the name?

@betwixt going from left to right, power supply 12v goes to PIR which has left side for PS and right side for LED strip, after pir comes led strip...i think that pir act as switch...i sent in previous message, a pictures of pir with specs....i think that PS is cut when PIR goes off
yes i am willing to build another circuit you give me, but need just time to get them....in previous messages you can see that people found way to get fade in effect, but no fade out...when pir is off, led light is off immidiately

@KlausST please do not be mad always, for you this is easy, but for me is not, i am trying on my second language outside of my field of work, to be precise and explain everything in proper way....

this scheme made by @BradtheRad was great when i have switch, and it worked great fade in fade out...but with PIR only fade in is what i get...no fade out

http://tinyurl.com/27ugsjb5

 

[D.A.(Tony)Stewart]

1. can you solder a few extra RC parts and a small NPN on a breadboard and add a 5W heatsink to the FET with an insulator?
2. is active low =0V ON?
3. what voltage is off? (from sensor)

answers?

You must know how to get and solder specific resistors and small leaded caps! (Mouser, Digikey or hobby store)

 

[zoxzox]

1. Yes i can solder, but for some complicate things i have friend who knows to do that...just give me scheme and i will give it to him
2. do not understand that.....but let me answer how i understand...OFF means circuit is open and led is OFF, ON means circuit is closed and LED is ON
3. i do not know off voltage, you mean voltage when sensor is off, i must tell friend to measure it

 

[D.A.(Tony)Stewart]

No I need the trigger voltage from the sensor

On =0V ?
Off = open or ?V

--- Updated Oct 9, 2024 ---

All parts connected to FET depend on Vt=1.8 +/- ~25%

V GS(th) Gate Threshold Voltage 1.35 to 1.80 to 2.35 V so delay to ramp and 5 s on/off ramp time are subject to differ from simulation here