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30A LED dimmer will not work for controlling electric throw?

bertus

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Audioguru

Sep 24, 2016
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Years ago my Electric Utility Company gave away compact fluorescent light bulbs for free to promote low power usage by replacing high current incandescent light bulbs. The new bulbs were No-Name-Brand Chinese and some caught on fire then dripped flaming plastic. They were all recalled and were replaced with better quality Name-Brand ones. They discovered that the manufacturer copied the certification number from a competitor so the bad light bulbs were never tested and certified to be safe.
You buy cheap then usually you get cheap poor quality stuff.
 

jon5500

Oct 31, 2020
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Years ago my Electric Utility Company gave away compact fluorescent light bulbs for free to promote low power usage by replacing high current incandescent light bulbs. The new bulbs were No-Name-Brand Chinese and some caught on fire then dripped flaming plastic. They were all recalled and were replaced with better quality Name-Brand ones. They discovered that the manufacturer copied the certification number from a competitor so the bad light bulbs were never tested and certified to be safe.
You buy cheap then usually you get cheap poor quality stuff.

I probably have some of those CFL's, or at least similar ones. Years ago, the local Walmart was selling "100 W equivalent" ones for a $1 a piece. Since I was building a video soft lighting system, I bought about 30 of them. They were never used for anything other than for the video. The ones I didn't ever use are still in their boxes.

I mostly use LED lighting throughout the house but, even with name brand ones, I have had intermittent internal shorting every now and then. I don't think they do well with power surges either and I have a lot of them.
 

jon5500

Oct 31, 2020
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Hello,

A quick look tells me that the 555 and 358 are powered by the 78L05.
That way the mosfets will not be driven hard enough to work cool.
Replace the 78L05 with an 78L10 and see if that changes the heat production.
https://eu.mouser.com/ProductDetail/STMicroelectronics/L78L10ACUTR?qs=YNC6WXvLPRbYRGEhI8BGOQ==
Also add an 330 nF capacitor on the C1 spot, wich is empty now.

Bertus

Thanks. Well, before I start replacing anything, I have another unused dimmer. It looks identical to the current one, but the circuit inside is slightly different. I only briefly noted the differences when it was opened, but I will have another closer look.

I still welcome any set ups where I could monitor these on a longer term basis and yet maintain a safety factor. I found my old linear 12 VDC supply and now I could try feeding it that, plus switching and I do have a high current 12V battery too. Fuses can be great, but components can still smoke/ fire anyway.

I may not be able to do anything more with these dimmers for a few days, however, so welcome any further information or suggestions.
 

Audioguru

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My government recently gave me some LED light bulbs for free. Some of them blink off then back on a few seconds after being turned on.
 

Incony

Apr 4, 2017
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i power my inductive motor car fan, on an MGF, which used to use resistive switching to control it ( 3 different speeds plus full )which can draw up to 15A at 12v, i wanted variable control, not switched speeds, so removed the resistive assembly, and used one of these.. https://www.ebay.co.uk/itm/PWM-DC-M...DC-9V-60V-20A-Potentiometer-New-/282495736134 its been in the car over 4 years now... and works fine... the motor can draw about 13A , but the unit doesnt even get warm. and yes, the switch on/off method isnt ideal, but at that point there is no current.. so the switch is not subject to current sparks at turn on / off time.. upload_2020-12-9_13-35-58.png
 
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jon5500

Oct 31, 2020
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Thanks for the info on the car PWM application. Well, out of the 5 dimmers of the same type I had, two burned up. I described the one here, but the other never seemed to heat at all and suddenly smoked too. It's good though that your PWM controller for the car has lasted that length of time without trouble. As for me, I decided to power the throw differently for now without any dimmers as I could no longer trust them.
 

Incony

Apr 4, 2017
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Thanks for the info on the car PWM application. Well, out of the 5 dimmers of the same type I had, two burned up. I described the one here, but the other never seemed to heat at all and suddenly smoked too. It's good though that your PWM controller for the car has lasted that length of time without trouble. As for me, I decided to power the throw differently for now without any dimmers as I could no longer trust them.


i understand, i knew i had a resistive load, and therefore i needed something to control current.. and pwm is the answer i used a DC current measure to determine what the load could actually be, before i chose the unit, to control it.. since temperature, affects resistance... its horses for courses... mine is certainly better than a hot resistor sitting under the dash. MGF really didnt consider the consequence of that, they actually burn out the the resistor terminals .. and one resistor costs more than the unit i used to replace them.
 
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