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How do you mean the pot wiring?
It's just a variable resistor in this layout from 0R to 500k.
LEDs: I'll use it just for 5-10W GU10 LED bulbs nothing extra.
But I even tested it with two 50W halogen GU10 bulbs as well.
Output images: due to automatic brightness controll, I guess it wouldn't be...
I attach the final version (and the parts list and the LT Spice files) with these mods applied:
series 18k resistor added to the pot to set the minimum level so the pot starts really from zero
22n + 3n3 experimented to the the ideal max delay time to reach the max power at the max pot level...
Just a little update: there was only 2 issues I'd like to solve but they are ok now.
I attached the new schematic with the 2 changes highlighted.
1) The 2W 100k resistor at the PS was just a starting value and a waste of energy.
I tried higher values and fortunately even a 470k is enough
so now...
I just finished the completly new v2.0 of my dimmer and (rarely I have this experience... but :-))
everything is perfect for the very first time...! :razz:
The dimming is now perfect without any flicker, it goes from 0% to 100%
even the controlling linearity is better, follows the pot nicely...
It's simple: the 1nF conducts right after the zero crossing to open the transistor.
Then the transistor pulls down the voltage on its collector.
There is also another 1nF capacitor after that to generate just a pull-down pulse.
And the lefty 1nF will be discharged via the 470k when the...
Wow, I tried a IRF730 MOSFET as switching device and it is much better now...!
It can drive any of my previous loads perfectly without getting even warm.
But being such an ideal and fast switch, now at the lowest PWM level my LED bulbs
are starting to shine at ~40%... :oops: The impulse is so...
Yes, I'll do exactly this: using a simple 555 with zero-cross triggering + delay to create a trailing edge dimmer for my LED bulbs.
I'll report about the results... ;-)
Out of curiousoty I measured the LED bulb current
on the same series resistor but driving them directly
from the mains at the current looks like this.
So I guess it's definitely designed for phase based dimming.
My dimmer works with resistive load perfectly.
I'll try it with a MOSFET as well...
I tried some snubbers on the load but it didn't help to make the BUX cooler.
I'll try some other mods with this layout and meanwhile I'll build another
dimmer with a zero cross synced trailing edge kind of operation just to
check whether it helps to eliminate my current issues.
BTW during...
Now I tried to dim the LED bulbs in series with the resistive dummy load and such way it works perfectly: no flickering and the BUX is cold as well.
The LED bulbs still have this step in current and a little resonance but otherwise everything looks good.
So maybe there is some oscillation when...
I made a ~20W resistive dummy load to check both the flickering and BUX temperature issues:
But with this load the switching is perfect:
The BUX is cool not even warm... (around: 25 - 30C°)
And with the LED I can see that there isn't any flickering neither.
So I guess it's sucks that the...
I checked this resonance with a same resistance dummy resistive load + normal
5mm white led in series and the current waveform on the load was a perfect
square so I guess it's generated by the bulb or together with my dimmer.
And even the BJT wasn't so hot.
Do you have any idea how to solve...
Ok, thanks!
I checked the 555 consumed currents on spice (with a normal, non-CMOS 555 model)
and I realised that there is one more "big" consumer, the 1k at the discharge ping with
this standard 555 PWM layout as this node is on V+ when the output state is OFF:
Do you have any idea to decrease...
No opto + direct drive + common GND:
Yeah, I also thought on this but I am not sure:
how to calculate the current needed for switching a MOSFET?
Let's take this example with this IRF840 Power MOSFET:
Vdsmax=500V Idmax=8A Vgs=10V Rds=0.85R
Input capacitance is 1.3nF right?
So to have the...
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