I'm in need of inductor designs for 120vac incandescent dimmer applications. Where is a good place to find an engineer to do this for me. I've been looking around for quite a while and it seems like no one needs the work! I desperately need solid performing inductors for my projects asap. Thank you!

 

You need an iron powder core, usually a Micrometals #26. You need at least 1.5mH divided by the current (i.e. 1.5mH @ 1A, 150uH @10A), the more the better. Micrometals website has an inductor designer app which has a choice of 50Hz/60Hz filter applications. The iron powder inductor is quite lossy at high frequencies, so dissipates the interference as core loss instead of reflecting it around the circuit.
Who still uses filament lamps?

 

I'm in need of inductor designs for 120vac incandescent dimmer applications. Where is a good place to find an engineer to do this for me. I've been looking around for quite a while and it seems like no one needs the work! I desperately need solid performing inductors for my projects asap. Thank you!

Or no one can do the work. It's not like there is a university course in inductor fabrication. Most of us learn by the seat of the pants, maybe you'll have to do that as well.

 

Ian presented the good choice: The filter core manufacturer. The typical frequency of dimmer noise is fairly well known, and once the mains frequency, and current are known, an inductance range can be calculated.

Really, though, FRI filters for light dimmers could usually be bought for less than the cost of fabricating them, unless the quantity built will be very large and the local labor very cheap. That variety of filter choke would be a commodity item would be my guess.

 

Ian presented the good choice: The filter core manufacturer. The typical frequency of dimmer noise is fairly well known, and once the mains frequency, and current are known, an inductance range can be calculated.

Really, though, FRI filters for light dimmers could usually be bought for less than the cost of fabricating them, unless the quantity built will be very large and the local labor very cheap. That variety of filter choke would be a commodity item would be my guess.

Well unfortunately mathematics and inductor design isn't in my wheel house either is electronics for that matter. I did take Ians advice(thank you Ian!) and I did reach out to Micrometals and they are trying to help me but they need inductance values for each one of my dimmer designs in order to fabricate inductors for me. Ian did give me a formula to calculate the values but quite honestly I cannot figure it out. I've done hours of research, but the more I read, the more confused I get. There are so many variables in this design and you are correct on off the shelf inductors for my application, but I want the very best inductor design as possible for my products and I do not spending more money for better performance.

 

The very best filter design would eliminate all frequencies except the fundamental. It would need 66mH and 33uF for a 10A load, would be bigger than a house-brick and cost a fortune.
What will happen is that you will go for the smallest inductor that passes the EMC regulations, that that is, from empirical observation, about L≈1.5mH/I

 

The very best filter design would eliminate all frequencies except the fundamental. It would need 66mH and 33uF for a 10A load, would be bigger than a house-brick and cost a fortune.
What will happen is that you will go for the smallest inductor that passes the EMC regulations, that that is, from empirical observation, about L≈1.5mH/I

Thank you so much Ian. I really appreciate your help/advice. In your equation is the current watts, amps, or ma? Thanks again!

 

Quite correct about an ultimate filter. And as I have mentioned before, much of engineering is finding the compromise between cost and effectiveness.

 

Using keywords and rambling to guess why would a person want to use an inductor to dim a bulb. keywords deduction re induction.
Using inductance to lower the current of a sine wave would be attenuation of low frequency power circuit.
It could use destructive interference or canceling. On top of that, the light bulb is a non-linear resistor because of the tungsten W.
The concept is the wave travels back and forth but when it arrives into your living room and thru the transformer it collides
with a wave having less than 180 degree phase angle. Different approach in this this schema is to collide, filter, non-linear, attenuate, unbalance, resonate, cancel and this causes the circuit breaker to warm because one half of the house wiring has become slightly unbalanced. Unbalance the house wiring to dim a bulb. AC feedback, yes maybe an awareness of all the canceled waves that inductance and harmonics get out of phase.
Some think the earth center is iron and the electrical universe in the big picture effects our power grid,

Another method was an AC welding transformer with a secondary that could move and that adjusted the amperage however in this case the amperage is much lower. Maybe size T75 iron ferrite or less depending on the light bulb wattage. same thing the arc is non linear.

Some others are less known and for a good reason and there is nothing magical there either.
Motors and generators another magnetic inductors out of phase.

Dr Frankenstein and Nick Tesla used high voltage so don't need that, but Edison effect could be in there some how.
Hewlitt and Packard audio generator used non linear tungsten to burn off some gain and it also involved low frequency,
both series and parallel resonance as filters, oscillator, feedback.

 

I am guessing that the inductor is required for reducing the electrical interference radiation, rather than as part of the dimmer function.The inductor is not related to the dimming function.

 

You are correct. I'm using scrs for the actual dimming part

 

Hewlett and Packard audio generator used non linear tungsten to burn off some gain

Actually, Hewlett (without Packard) used the self-heating of a PTC thermistor to set the gain. That PTC thermistor just happened to be a filament lamp. Nothing was "burned off".

 

Actually, Hewlett (without Packard) used the self-heating of a PTC thermistor to set the gain. That PTC thermistor just happened to be a filament lamp. Nothing was "burned off".

Holding a constant amplitude as the frequency was varied was the big challenge and using a relatively small tungsten filament light bulb was a brilliant design move at the time. That "Excess Gain" is required to be available as the conditions varied with the frequency.
Creating a signal that keeps a constant amplitude is still a bit of a challenge even today.

OOPS!! we have replied to a different thread. This one is about dimmers!!

 

For the dimmers design thread: " I'm in need of inductor designs for 120vac incandescent dimmer applications."
Is this a "one-off" project or for a production run of many devices?? Most of the commercially available dimmers that I have replaced because they failed use what looks like the cheapest possible iron-core chokes that can be produced.
So the question becomes one of "what standard requirements must be met", versus how much "noise power" is generated that must be reduced by some amount?
And the amount of the higher frequency components in the noise depends on how fast the SCR devices are switching, and at what voltages they are switching. So either a great deal of insight is required, or a fair amount of noise spectrum measurement are needed.
Probably the spectrum measurement approach will be simpler and more accurate.

 

Holding a constant amplitude as the frequency was varied was the big challenge and using a relatively small tungsten filament light bulb was a brilliant design move at the time. That "Excess Gain" is required to be available as the conditions varied with the frequency.
Creating a signal that keeps a constant amplitude is still a bit of a challenge even today.

OOPS!! we have replied to a different thread. This one is about dimmers!!

Just correcting @sparky 1 ‘s rather tangential assertion in Post #9.

 

For the dimmers design thread: " I'm in need of inductor designs for 120vac incandescent dimmer applications."
Is this a "one-off" project or for a production run of many devices?? Most of the commercially available dimmers that I have replaced because they failed use what looks like the cheapest possible iron-core chokes that can be produced.
So the question becomes one of "what standard requirements must be met", versus how much "noise power" is generated that must be reduced by some amount?
And the amount of the higher frequency components in the noise depends on how fast the SCR devices are switching, and at what voltages they are switching. So either a great deal of insight is required, or a fair amount of noise spectrum measurement are needed.
Probably the spectrum measurement approach will be simpler and more accurate.

Thanks for your reply. I'm mass producing these units. I've inspected commercial dimmer designs as well and the components used are the cheapest available. I have seen a ton of burned inductors/chokes.

 

1499066443287039069-US20160381745A1 (storage.googleapis.com)

The schematic shows a 30mH inductor, the patent is legit. Steinmetz told them it was a glitch
and after enough disasters they made the necessary changes. Phase forward dimming circuit
with inductor might tell us something important,

 

1499066443287039069-US20160381745A1 (storage.googleapis.com)

The schematic shows a 30mH inductor, the patent is legit. Steinmetz told them it was a glitch
and after enough disasters they made the necessary changes. Phase forward dimming circuit
with inductor might tell us something important,

It says most about the US Patent office. The rectifier inductor capacitor power supply has been around since the thyrsitor was invented.

 

Every one of those dimmers in the patent is far more complex than any of the dimmers that I have seen for residential applications. And the bi-filar line filter is something I have not seen in any residential dimmer so far. A good idea, but I have not seen it yet.