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### Author Topic: kids oven and stove led circuit  (Read 27789 times)

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#### kam

• Hero Member
• Posts: 1849
##### Re: kids oven and stove led circuit
« Reply #30 on: September 19, 2015, 15:45:00 PM »
Your regulator is fine to have a stable voltage. you do not need to add anything else. If you want full brightness, you really need higher voltage supply. this is due to the voltage drop on the transistors.
You can try higher capacitors but already you've changed the circuit a lot and i cannot follow unless i calculate the circuit all over again. And unfortunately time is a luxury that i do not have right now.

So, you want something that you turn the pot to a value, and the leds simply follow with a fade in/out delay. You can try this for a change. Use the 317 to make a voltage regulator 5 to 14 volts. Do the calculations to find the proper resistors needed to achieve these values. Remember that you need a higher input voltage, at least 17 volts. You can go with a typical 24V power supply as well.
Then what you wanna have is a voltage hysteresis circuit. You can use this circuit LED Fade-In Fade-Out Dimmer (i'm talking about the first one). Remove the switch S1 and then connect the output of the lm317 directly to the R1 of the fader. Like before, you need to remove R3 since your leds already have a limiting resistor. The 12V input indicated in the circuit are taken of course out of the LM317 circuit that you made.

Is this what you've already done so far? If not, give it a go. This should work.

#### EricD

• Newbie
• Posts: 25
##### Re: kids oven and stove led circuit
« Reply #31 on: September 20, 2015, 04:43:18 AM »
Right now my dimmer on the lm317 is an adjustable current regulator and is AFTER your fade delayed circuit. I'll switch their order to put them like you said.

I tried it before but when I powered the circuit it was charging to full capacity without being influence by the pot. This was because the base of tip121 was the Vout of LM317 but the collector was on the main 12v of the power supply. Reading your post make me realize my mistake.

My first try was your first circuit and the only change I made was swapping the 470uf for a 1000uf and have more delay. Then I've put another 1000uf in parrallel so time was extended.

T= R.C = 33K.2mf= 66s (to full charge?)
Imax (t=0) = 363.6 uA
Qmax (t-->♋) = 24 mC
*Can't find infinite symbol

Looking at Imax how have it lit in the first place???

#### kam

• Hero Member
• Posts: 1849
##### Re: kids oven and stove led circuit
« Reply #32 on: September 20, 2015, 16:52:37 PM »
there is a transistor there amplifying the current but 100s of times...

Try the setup that i described. The lm317 has to be connected as adjustable voltage supply, not current!!!

#### EricD

• Newbie
• Posts: 25
##### Re: kids oven and stove led circuit
« Reply #33 on: September 21, 2015, 07:49:10 AM »
With the LM317T the voltage go directly to the other circuit (fade n delay) or maybe i did something wrong when wiring.

The Vout of my voltage regulator was going in the base of the tip121 that I'm using in your fade in/out but the collector was plugged to the  power supply 12V and not to  the output of my voltage regulator like the base was.

I've kept the circuit and worked at the other end of my breadboard so it will be fast to test it again but not tonight...it's almost 1:00 AM here in Montreal and I'm working. I go to sleep almost at 2 o'clock every night since I start this project. Would be ok if I didn't had to wake at 6.

*I don't have something higher than a pc power supply regarding DC V.

#### EricD

• Newbie
• Posts: 25
##### Re: kids oven and stove led circuit
« Reply #34 on: September 21, 2015, 09:12:01 AM »
Just found this link on another website but just miss it while surfing yours

http://pcbheaven.com/circuitpages/LED_PWM_Dimmer/

Got everything in my stuff so if pwm is the ticket, I think we might have a winner...

#### EricD

• Newbie
• Posts: 25
##### Re: kids oven and stove led circuit
« Reply #35 on: September 23, 2015, 08:28:05 AM »
Ok I tried it the way you told me and it works. I did put the power supply 12v inside the collector instead of feeding it with my regulator's Vout.

I placed 2 1000uf capacitors in parrallel to see the delay.

-When moved only a little nothing happen, just more brightness.

-When moved fast there's something like 2 sec of delay before the fade is applied.

-When power on the minimum brightness takes lot of time to happen but your 2nd fade circuit show how to have a minimum charge in the capacitors.

-When set to max it's still not fully bright but you told me that I need more power. I prefer heading for an LDO solution with less than 0.5v dropout.

-When set to max the leds are flickering amd this may be just becaused nothing is solder. Unless noise could happen but I've read just an intro on this subject.

I'll put a video tomorrow so you can see.

#### EricD

• Newbie
• Posts: 25
##### Re: kids oven and stove led circuit
« Reply #36 on: September 25, 2015, 07:16:31 AM »
Disappointing...

It just won't work that way. So much te spent but at least I'm keeping the knowledge I gathered.

It seems to be phase-shift dimmer that I'm looking for if I go all the way with leds. When pot moved from point A to B the change of brightness is not instant but starts slowly fade to reach the new set value over a certain time.
Hysteresis, from what I've read, will kicks in when the voltage overpass a certain point (1/3 - 2/3 of voltage).

Doin this project with leds makes it harder. Bulb light are resistive so dimmer are more user friendly and leds will dim by regulating the amount of current. But even with a good adjustable regulator, some leds in the string will be brighter plus capacitors charging/discharging will be really tricky (sometimes to quick other times to long).

Do you know how to achive pwm dimmer with phase shift? If this way is not possible then only programation of software in a chip woll work.

P.s: video only show jothing (everything*) but succes plus dark to see and me trying to speak english in a shy way.

« Last Edit: September 26, 2015, 05:52:19 AM by EricD »

#### EricD

• Newbie
• Posts: 25
##### Re: kids oven and stove led circuit
« Reply #37 on: September 27, 2015, 16:23:07 PM »
I tried to upload a video file from my cellphone but it didn't worked so I'll try from a pc later today.

I've removed the LM317 and plugged the VR wipper directly to the 4.7 KOhms of you fade in/out simple circuit givin me back +2v. It was way much better. I still need to swap the 2 resistors to improve voltage adjustment but the range was already wider and the leds more brighter.

I'm considering using your 2nd fade circuit since it have more flexibility to have longer response time.

I didn't think it would be such hard work when I step into the project. Knowing not enough I had to go through loads of information and this made a long road to succeed.

As a representative my machines problems troubleshooting were improved and my boss even suggest paying for an electronic class and take me as a repair technician.

Thanks for your patience and i'll share the final results with you I promise!