15
votes
Accepted
Powering and dimming a few hundred light bulbs
DO NOT drive it AC (mains) power!
AC mains installation/implementation expert here.
AC mains power is much more dangerous and requires great care.
It will create a huge mess when a bulb burns out, as ...
11
votes
Use household power strip for 12V/24V power
It will function, but using standard plugs and sockets for the wrong voltage is a spectacularly bad idea. This relies on you being in total control, remembering everything about your setup forever, ...
10
votes
P-channel FET won't turn off from micro
That is a fairly massive power MOSFET, with a lot of gate charge ~250nC.
I would expect it to take the better part of a millisecond to turn off with only a 10kΩ resistor to drain that charge away. The ...
6
votes
How can I reduce the current draw for a dimmer with a triac for an immersion heater?
Current draw is determined by the heater power you need. If you can reduce the heater watts, do that. I'll assume that you have already sized the heater.
Both triacs and IGBTs have relatively high ...
6
votes
How to dim my dc push button led switch that is too bright?
This seems to be the only relevant part of the pictures you posted:
It seems to show that the LED connections are independent of the switch connections.
To decrease LED brightness, you decrease the ...
- 315k
6
votes
Would it damage a tile saw if I used a a dimmer switch on it?
Light dimmers are not meant to be used with inductive loads like motors. You will destroy it pretty quickly. You can buy dimmer/speed controllers that are meant for use with motors.
The tile saw is ...
- 4,309
6
votes
Accepted
Would it damage a tile saw if I used a a dimmer switch on it?
Most dimmer switches are rated 500 watts max and a 10" tile saw might be 1500 watts. The nominal current consumption of the motor is already three times the maximum of the dimmmer switch. Worst is ...
- 1,705
6
votes
Accepted
Night light broke after trying to dim LEDs
Most likely you did not measure the power, but rather the current. The power when the LEDs are off is low but the current will be almost unchanged. Trying to interrupt the current would require a high ...
6
votes
Night light broke after trying to dim LEDs
Yes, that is a very common arrangement. Nowhere is it said that if the LEDs are off that device must conserve power. It just works best like that, because when the transistor is off, the LEDs limit ...
- 172k
6
votes
Powering and dimming a few hundred light bulbs
No need for 12V - totally impractical. If the bulbs are already wired in parallel then someone messed it up and it has to be all redone.
You’ll be making series strings of 10 bulbs, and those strings ...
6
votes
What is the importance of R1 connected in this circuit?
If \$R_{1} = 0\ \Omega \$, and \$V\!R_{1}\$ is adjusted to \$0\ \Omega \$, then the current through the DIAC and the gate of the TRIAC would be too high, causing one or both to be destroyed.
- 17.1k
5
votes
Led Bulb Flicker when duty cycle is below 40%. What is wrong with circuit?
This looks like a mess waiting to catch fire or electrocute someone.
You don't say where this is, but almost certainly some part of the AC line is tied to ground somewhere. That means you have a ...
- 315k
5
votes
Accepted
0-10V Digital Rheostat for LED Dimmer?
Many of the LED power supplies such as those by Mean Well, etc., offer three modes of control: output constant current level can be adjusted through the control input by connecting a resistance or 0 ~ ...
- 180k
5
votes
Accepted
Replacement Triac
The proposed replacement is 25x more sensitive with regard to trigger current in the relevant quadrants. Current rating is probably okay. Voltage rating is similar (and not very generous for 220V ...
5
votes
Accepted
Why does this dimmer switch have reduced wattage capability for LED / CFL bulbs?
Since dimmable LEDs don’t use active PFC for cost reasons, the peak/average current is much higher, called the crest factor, so conduction losses demand this de-rating of power limits in a Triac ...
- 148k
5
votes
Accepted
Reverse Phase Dimmer MOSFETs
GND is a term we can attach to any node on a circuit, usually it's a node with a lot of common connections and we usually refer to other voltages relative to that.
It's not uncommon to have a node ...
5
votes
Arduino PWM LED lights dimmer using MOSFET - Rise time problem
I see two possible solutions:
Depending on your PWM frequency you might be seeing the capacitance from the LEDs. This might be normal. Try to removed the LEDs and replace with a resistor and measure ...
- 111
5
votes
What is the importance of R1 connected in this circuit?
R1 limits the maximum current into the TRIAC gate when VR1 is at 0 Ω.
Because it is only about 1% of VR, it has very little effect on the brightness adjustment range.
- 23.2k
5
votes
Dimmer for 2 halogen headlights
Expect short lamp life time when you dim Halogen bulbs. There is a minimum temperature they need for the Halogen cycle to operate properly. When operating properly the tungsten evaporated from the ...
- 5,298
4
votes
Accepted
Analog Dimmer Circuit Analysis
Solution is all but trivial.
A rather good starting point would be doing the following assumptions valid for a resistive load:
1)Each cycle will start with C1 fully discharged and open TRIAC U2.
...
- 3,242
4
votes
Best Lamp Dimming Circuit?
In general for dimming a lamp following is applicable.
Make the amount of power going into the lamp variable
Prevent as much as possible the loss of power in the controller
In many domestic dimmers ...
- 3,940
4
votes
Accepted
Why triac output goes higher than line 230-240 voltage in AC dimmer circuit?
Line voltage is 240 volt and output voltage goes till 328 volt. Is
this normal working of triac BT139 or I am doing something wrong?
If the RMS voltage is (say) 1 volt then the peak voltage will be ...
- 473k
4
votes
Accepted
TRIAC not turning off correctly
Your TRIAC does turn off correctly. Remember, it's turning off automatically as soon the current through it is zero. Not as soon the voltage over it is zero.
What you have there is a slightly ...
- 14.4k
4
votes
Accepted
How can I dim 50 high-power LEDs in series with an Arduino?
An n-channel MOSFET is a great way to dim LEDs. Something like the IRFZ24N is likely what you'd want - it can handle way more amperage than you'll ever need, and pretty cheap.
The way you drive an ...
- 410
4
votes
Accepted
AC PWM Dimmer with Arduino, but the light is on even when Arduino is off
When it is activated, the optocoupler turns off the MOSFET, otherwise it is turned on via the 100k pullup resistor.
Therefore when the arduino is off, then the optocoupler is off, and the MOSFET will ...
- 81.6k
4
votes
PWM LED strip dimmer induces noise in power supply
PWM-ing the output of a switched mode power supply (SMPS) is nothing different than testing its transient response (e.g. 0-to-100% then 100%-to-0), but way faster. Load transients are normally ...
- 38.5k
4
votes
Accepted
How do I control the sensitivity range of an LDR-controlled LED?
You can try replacing the 30K resistor with a 500K rheostat with 10K in series, and adding a second transistor to make a Darlington pair.
simulate this circuit – Schematic created using ...
4
votes
How do I control the sensitivity range of an LDR-controlled LED?
If you move the LED and the 100 ohm resistor to the emitter path and connect the collector directly to 5V, you remove the voltage gain of the transistor and use only the current gain.
This uses a ...
- 8,335
4
votes
How do I control the sensitivity range of an LDR-controlled LED?
Generally, you want low gain in this circuit; you also want plan what you need the circuit to do.
The LDR conductivity (1/R) is approximately proportional to the incident light. Human perception of '...
- 20.3k
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