Different specs for dimmer switch speed controls ?

[Joe Gwinn]

That probably explains why the thing failed.

LM317 is a very widely used regulator chip. The problem is that the circuit isn't designed to handle the load imposed by the motor in practical use:

If one stalls the motor by preventing bobbin rotation, the current will shoot up. This is perfectly normal, and must be accommodated.

DC motors can generate large voltage spikes, which spikes can blow unprotected solid state devices. Are there any protective components in parallel with the motor? (A capacitor helps, but isn't usually enough.)

I think there is [a big filter capacitor]. I'll have to open the thing up and take a photo.

Motors don't really need their DC to be clean, so there may well not be such a capacitor.

[wallwart is] 9V, 500mA.

Probably a 6-volt motor. Motors are not that fussy.

[RedHouse]

Oh yeah... duh...



Here's some I took a while back. When I get a chance I'll take the non working speed controller board out and take a photo of it. I had replaced the motor, which turned out to be fine.

I like how they hold the motor in there with a can-cap bracket. Reminds me of Danelectro thinking.



Seems like they could/should have gone to the trouble of making a proper PCB instead of that strip-board circuit ...for the kind of money they get for those winders.

[Steve Conner]

That's a motor from an old cassette deck, with a built-in speed regulator. I remember them from dismantling old stereos as a kid.

The actual motor is in a rubber mount inside the can, and the little round regulator PCB is soldered to the back of it. Maybe that's what has blown and you can bypass it.

[tonedeciple]

That's a motor from an old cassette deck, with a built-in speed regulator. I remember them from dismantling old stereos as a kid.

The actual motor is in a rubber mount inside the can, and the little round regulator PCB is soldered to the back of it. Maybe that's what has blown and you can bypass it.

You could use an rpm selector from a turntable and name the pickups "The 33-1/3rd," "The 45" and "The 78"

[rdrr]

There are lamp dimmers that work well with universal-wound motors. Lutron is a good brand.

When you say lamp dimmer are you talking about those floor lamp dimmers that you plug the lamp into or are you talking about something along the lines of a florescent safe light dimmer? If it's the floor variety then it's just a matter of wiring a sewing machine motor up to a plug and plugging that into the dimmer, right?

[Joe Gwinn]

When you say lamp dimmer are you talking about those floor lamp dimmers that you plug the lamp into or are you talking about something along the lines of a florescent safe light dimmer? If it's the floor variety then it's just a matter of wiring a sewing machine motor up to a plug and plugging that into the dimmer, right?

Actually, I was talking about wall-mount dimmers. Some of the in-cord lamp dimmers will also work, if the dimmer is large enough. I have no idea what a "florescent safe light dimmer" is.

The wall-mount dimmers with a knob are easiest to use for motor control, and are large enough. One puts the dimmer in a handi box (the one with rounded corners, available in electric supply departments of hardware stores), adds a line cord (to plug into the wall), and wires the universal motor in where the lamp would have gone.

If you are adventurous, add a 25-amp 250-volt (or larger) full wave rectifier bridge between dimmer and motor. The two AC terminals go to the dimmer (where the light would connect) and the DC terminals (marked plus and minus) go to the motor. It does not matter which way the motor is connected to the DC terminals of the bridge. The advantage of the rectifier bridge is that it make the speed versus knob position more linear, especially at low rotation speeds.

[RedHouse]

...I have no idea what a "florescent safe light dimmer" is....

The new "safe" dimmers are built different (to allow the start-up surge?) they have 3 wires so they get their source and reference voltage from the mains regardless of their output state IIRC, coincidentally I had to learn a bit about this myself recently.

The Story...

I had been using the florescent bulbs in my four outside light fixtures on my house until recently when my wife and I were at a friends house who had those in-wall on/off timers installed and she like them an wanted those for our house since we do at times forget to turn off the outside light specially during the winter.

So I went down an bought some in-wall timers, installed them all, programmed them, and then after a couple days noticed I had some bulbs out, so I replaced them, few days later, more out.

I was wondering if I had got a few bad bulbs, I had bought a case of 12 bulbs and these things usually last at least 6-months, but now I loosing bulbs evry 2-3 days. Then one night I came home to find the porch light "strobing" it looks like a tube florescent when the starters going out, kept trying to strike itself into florescence. So I looked into it a bit deeper and found this whole "florescent safe" thing (which I didn't care to learn about at the time so please don't ask "why") which requires the 3-wire connection or it trends to blow the bulbs.

Since I had just spent $35 per for my 4 units, and didn't really want to drop another $140.00 for 4 more "safe" ones, needless to say I installed regular candescent bulbs back into my outside light fixtures, so much for the green thing.

[Joe Gwinn]

The new "safe" dimmers are built different (to allow the start-up surge?) they have 3 wires so they get their source and reference voltage from the mains regardless of their output state IIRC, coincidentally I had to learn a bit about this myself recently.

The Story...

<<see above>>

Hmm. Interesting. What is the make and model of the safe dimmer? Are any patents listed on dimmer or documentation?

Three-wire dimmers may be better for control of DC and AC/DC motors, and for control of incandescent lamps (and some kinds of motor) through a step-down transformer.

[RedHouse]

Hmm. Interesting. What is the make and model of the safe dimmer? Are any patents listed on dimmer or documentation?

Three-wire dimmers may be better for control of DC and AC/DC motors, and for control of incandescent lamps (and some kinds of motor) through a step-down transformer.

Mine were the "timers" not dimmers (Intermatic brand) I was just saying in that story it was then I got the news-update that there were some new controls in town.

[steelyman]

Leslie motor speed control...

>
I'd like to resurrect this old thread because I want to find a simpler way to control the motor speed of a Leslie unit motor.

IIRC, the Leslie motors are the old "brushless" type like in old record players and such, I'm not certain but I don't think you can use this type of speed controller with brushless motors.

I found this on Wiki...

Shaded-pole motor - Wikipedia, the free encyclopedia

...which I believe is what a Leslie motor is.

Then, I found this...

KB ELECTRONICS KBWC-15K Vari-Speed Wall-Mount Motor Speed Control 5A 120 V.A.C. | eBay

Its specs are:

The KBWC-15K is a Distributor packaged Solid State AC Motor Speed Fan Control. It is designed for mounting in a 2" X 4" electrical wall box. It operates from 115 VAC, 50/60 Hz and has a maximum rating of 5.0 Amps @ 40°C. The KBWC-15K provides infinitely variable speed motor control for Shaded Pole, Permanent Split Capacitor and Universal (AC/DC) motors. The variable speed motor control contains an on/off line switch, a high gain RFI noise suppression filter, a minimum speed trimpot and a flame retardant ABS enclosure.

It's cheap enough, so I'll give it a shot and post my results.

[Steve Conner]

Compact fluorescent "energy saving" bulbs can catch fire and burn your house down if used with a dimmer or triac switch of any kind. It's one of the great forehead slapping moments of the electronics industry.

I have a friend who's working on a variable frequency drive kit. His main goal is to make a quartz locked, fine tuneable frequency source for running Hammond organs, but he also plans to offer it as a Leslie speed controller. As mentioned, just varying the voltage isn't the best way to control the speed of those shaded pole motors. It works when the load is a fan, because they need very little torque at lower speeds.

I've destroyed the ordinary dimmers trying to run universal motors, but I tried some other ones meant for halogen lamp transformers, and those worked great. Later I built my own phase angle controller that can "dim" anything.

[ken]

HF router speed controls only work well with universal (AC/DC) motors with brushes, but they work well for that. There is a trimpot hidden inside for finetuning the lowest speed point, it's usually a very small sized 500K trimpot wired in series with the 1M main pot. I have a Singer sewing machine motor on my winder that spins almost too fast to use, so I modified my router speed control to provide upper and lower speed limit control like this...

I removed both the trimpot and the main control pot from the board and replaced them with three 500K normal sized CTS pots wired in series. The pot that replaced the small trim pot in this lineup I use to set a 'low limit' so I can move the motor very slowly if I need to, the center pot is installed in an old volume control pedal so I can control the machine's speed with my foot, and the last one sets the 'upper limit' of motor speed. I use this if I'm trying to teach someone how to wind so they don't lose control of their machine. This setup works great with a winder, and best of all even the winding speed can be preset this way.

Don't get me started on CFL's.

ken

[David Schwab]

Compact fluorescent "energy saving" bulbs can catch fire and burn your house down if used with a dimmer or triac switch of any kind. It's one of the great forehead slapping moments of the electronics industry.

At a place I worked a few years back, we had track lighting on the celling. They were connected to dimmers. My boss didn't know you can't plug CFLs in, and was wondering why they would quit working after a while.

They didn't catch fire or anything, they just stopped working.

Don't get me started on CFL's.

I don't see a problem with them. I have replaced every incandescent bulb in my house with CFLs, and out electric bill is a lot better.

[ken]

I hate CFL's because I can't understand why we would want to use light bulbs that require a hazmat team to clean up after you break one. Think about it... an earthquake shattering thousands if not millions of those bulbs all at once would be an ecological nightmare. Besides, the strobing they do drives me nuts. I wish I could find a good LED home bulb that wouldn't cost an arm and a leg.

Anyway, I wish I could find a 110VAC speed control circuit that used a simple 10K control pot instead of the HF unit's 1 Meg control, so I could use digital pots and 'computer control' the speed of my Stevens winder's motor. I would like to use my original motor if at all possible, and the only small DC supplies I can find are relatively low voltage units.

ken

[Steve Conner]

Just because you haven't seen one catch fire yet... :O Rod Elliott has a great article on the subject.

I also found the "dimmer" circuit useful and wanted to remote control it. I designed another version that takes a control voltage instead of a pot. I intended it for firing monstrous SCRs to control several kilowatts, so it might be overkill for this job.