Dimmer question

run4jc · Oct 19, 2011

I searched but couldn't find an answer to this one - sorry if one is already posted out there!

I have an 'over stove' microwave light that I plan to mod to LEDs. Don Mcleish posted a photo essay of re-fitting his home with LED lighting over HERE - near the bottom of the web page are photos of his similar lighting mod.

My question - what would happen if I used a 'non dimming' driver with this 2 level light switch? I don't mind coughing up the extra $$ for a driver that will dim, but the space I have to work with is limited and the AC drivers I find that will dim are pushing the envelope as related to the space I have to mount one.

Seems to me that I remember reading that in this case, a simple 2 level switch (Hi - Lo - Off) would simply function "Hi-Hi-Off" if a non dimming driver was connected, and that would be perfectly okay with me - we never use the 'lo' setting any way.

I'm not an electrician or engineer (obviously) so I hope someone with knowledge of these things can keep me from blowing something up! Incidentally, my plan is to mount 4 warm XPGs (3.0Vf at 350mA) on 20mm stars, connect them to a 700mA driver in 2/2 parallel. I'll use a 12 watt 700mA driver, so the wattage should be no issue at around 4-5 watts.

I appreciate any help! I'd like to order this stuff today for an install on Saturday.

Thanks! lovecpf:bow:

LEDninja · Oct 19, 2011

Buy a 2nd driver.
Use 2 switches. One switch has a driver and 1/2 the LEDs.
Turn 1 switch on: 1/2 the LEDs light up - low.
Turn 2 switches on: All the LEDs light up - high.

If you have a different number of LEDs in each circuit say 2 and 4.
Switch 1 - 2 LEDs low.
Switch 2 - 4 LEDs medium.
Both - 6 LEDs high.

I got the idea reading how Cree do their dimming of some fixtures.
http://www.creeledlighting.com/Libraries/Recommended_Dimmers/CR_Troffer-Step_Dim.sflb.ashx

Easytim just bought small LED bulbs for the existing fixtures in his stovetop.
It is the 2 watt things he is using in his china cabinets. (He has taken his stovetop picture out (maybe PM him and ask why))
http://www.led-guy.com/

alpg88 · Oct 19, 2011

run4jc said:
I searched but couldn't find an answer to this one - sorry if one is already posted out there!

I have an 'over stove' microwave light that I plan to mod to LEDs. Don Mcleish posted a photo essay of re-fitting his home with LED lighting over HERE - near the bottom of the web page are photos of his similar lighting mod.

My question - what would happen if I used a 'non dimming' driver with this 2 level light switch? I don't mind coughing up the extra $$ for a driver that will dim, but the space I have to work with is limited and the AC drivers I find that will dim are pushing the envelope as related to the space I have to mount one.

Seems to me that I remember reading that in this case, a simple 2 level switch (Hi - Lo - Off) would simply function "Hi-Hi-Off" if a non dimming driver was connected, and that would be perfectly okay with me - we never use the 'lo' setting any way.

I'm not an electrician or engineer (obviously) so I hope someone with knowledge of these things can keep me from blowing something up! Incidentally, my plan is to mount 4 warm XPGs (3.0Vf at 350mA) on 20mm stars, connect them to a 700mA driver in 2/2 parallel. I'll use a 12 watt 700mA driver, so the wattage should be no issue at around 4-5 watts.

I appreciate any help! I'd like to order this stuff today for an install on Saturday.

Thanks! lovecpf:bow:

i have a floor lamp that had 2 position dimmer via triac to work with inc. bulbs, i installed e27 led bulb, when i turned the dimmer, light did not dim, my guess the driver compansated for lower current, so i have hi,hi,off.
but i'm not sure all bulbs\drivers will work like that, you have to actually test your driver with load current you plan to supply on 4xp-gs, working with current your dimmer supplies in both positions.

run4jc · Oct 19, 2011

Thank you both. Although I like the idea, 2 switches are not feasible in this application. The switch is a simple button on the front of the microwave. I think that Alpg88 has the right idea - just buy it and test it. I really don't mind the hi-hi-off scenario, and as long as I don't damage the driver it's all good. I removed the bottom cover of the microwave this morning to expose the simple 'guts' of the light kit. In the photo below (excuse the poor quality) you'll see small devices connected directly in front of the 2 existing incan bulbs. I'm wondering if perhaps those are the workings of the 2 levels? If so, I can easily by pass them. I'm going to take my multi tester and check the output at the terminals after the devices, and check it in front of the devices. Maybe I'll get lucky. I'll keep you posted!

alpg88 · Oct 19, 2011

another double post. have no idea how it happened, sorry

alpg88 · Oct 19, 2011

double post

Steve K · Oct 19, 2011

run4jc said:
I searched but couldn't find an answer to this one - sorry if one is already posted out there!

I have an 'over stove' microwave light that I plan to mod to LEDs. Don Mcleish posted a photo essay of re-fitting his home with LED lighting over HERE - near the bottom of the web page are photos of his similar lighting mod.

My question - what would happen if I used a 'non dimming' driver with this 2 level light switch? I don't mind coughing up the extra $$ for a driver that will dim, but the space I have to work with is limited and the AC drivers I find that will dim are pushing the envelope as related to the space I have to mount one.
.......Thanks! lovecpf:bow:

my guess is that the "dim" switch position just adds a diode in series with the AC power, delivering only half of the AC waveform to the bulb. This would show up as a significant voltage ripple at the input of your driver. Doesn't seem likely that it would hurt anything, but could produce 60Hz ripple in the light produced by the LEDs.

... or maybe there's a power resistor wired in series with the switch?? .... It takes very little reduction in the applied voltage for an incandescent bulb to dim quite a bit. This would have less impact on a LED driver.

regards,
Steve K.

run4jc · Oct 19, 2011

Steve K said:
my guess is that the "dim" switch position just adds a diode in series with the AC power, delivering only half of the AC waveform to the bulb. This would show up as a significant voltage ripple at the input of your driver. Doesn't seem likely that it would hurt anything, but could produce 60Hz ripple in the light produced by the LEDs.

... or maybe there's a power resistor wired in series with the switch?? .... It takes very little reduction in the applied voltage for an incandescent bulb to dim quite a bit. This would have less impact on a LED driver.

regards,
Steve K.

It's bound to be simple. It's a simple light, and I have to wonder if those 2 devices you see in the photo just before the bulbs have anything to do with it. Easy enough to check.

But if it won't hurt to quickly switch 'through' the low setting, I'm not going to worry about it. As mentioned, we don't use the low setting - if anything I want MORE light. Our cooktop is black (I miss my stainless/gas cooktop from my last house!) and lots of light is needed. In fact, my final decision is to use SIX XPG Q4 - 3000 color temp - driven in 2 banks of 3 each at 350mA. Each one is rated at 105 lumen at 350mA - 6 of them should provide about 50% more light than I currently have (I hope.)

We shall see! Thanks for the help, all

alpg88 · Oct 19, 2011

Steve K said:
my guess is that the "dim" switch position just adds a diode in series with the AC power, delivering only half of the AC waveform to the bulb. This would show up as a significant voltage ripple at the input of your driver. Doesn't seem likely that it would hurt anything, but could produce 60Hz ripple in the light produced by the LEDs.

K.

that would be easy fix than, jump the diode, or resistor and you get hi mode on both positions

run4jc · Oct 19, 2011

alpg88 said:
that would be easy fix than, jump the diode, or resistor and you get hi mode on both positions

Totally agree - and I'm thinking that the 'little white things' probably house those diodes - and hopefully I can determine that for certain with the multi-meter.

:thumbsup:

alpg88 · Oct 19, 2011

run4jc said:
Totally agree - and I'm thinking that the 'little white things' probably house those diodes - and hopefully I can determine that for certain with the multi-meter.

:thumbsup:

idk, looks like they are just plugs, diode or resistor would be before that wire that comes out from above the pic. and supplies power to both bulbs. imo

run4jc · Oct 20, 2011

alpg88 said:
idk, looks like they are just plugs, diode or resistor would be before that wire that comes out from above the pic. and supplies power to both bulbs. imo

You may be right - I hope not, but you probably are. I don't plan to trace back 'inside' the panel - if I can't find power before whatever device 'dims' the lights, let's just hope that the driver can handle a 'bump' through the low level!

run4jc · Oct 21, 2011

Well, no such luck. I can't get to where the dimmer is. I tested the voltage - on 'hi' it's 120VAC - on the 'lo' setting it's 64VAC. Hope I don't damage the driver, but I'm going with it - we'll just bump through the low setting quickly.

Any input would be appreciated! I'm hooking it all up tomorrow - gonna go set the 6 LEDs on MCPCBs with Arctic Alumina to a 1 inch square by 1 foot long hollow aluminum tube...that ought to make a good heat sink!

alpg88 · Oct 21, 2011

norrmaly those ac drivers work in range of 80-240v in that case it wont even turn on from 64v.
what driver are you using?

run4jc · Oct 21, 2011

alpg88 said:
norrmaly those ac drivers work in range of 80-240v in that case it wont even turn on from 64v.
what driver are you using?

Xitanium 700mA 17 watt...

alpg88 · Oct 21, 2011

its 120v driver, 99,9% it wont even turn on,

run4jc · Oct 21, 2011

That would be good - no need for the lower level - just don't want to damage the driver, you know? I'll post back tomorrow after I finish!

Thanks for the input - I appreciate it!

Dimmer question

run4jc

Flashlight Enthusiast

LEDninja

Flashlight Enthusiast

alpg88

Flashlight Enthusiast

run4jc

Flashlight Enthusiast

alpg88

Flashlight Enthusiast

alpg88

Flashlight Enthusiast

Steve K

Flashlight Enthusiast

run4jc

Flashlight Enthusiast

alpg88

Flashlight Enthusiast

run4jc

Flashlight Enthusiast

alpg88

Flashlight Enthusiast

run4jc

Flashlight Enthusiast

run4jc

Flashlight Enthusiast

alpg88

Flashlight Enthusiast

run4jc

Flashlight Enthusiast

alpg88

Flashlight Enthusiast

run4jc

Flashlight Enthusiast

Similar threads

Latest posts