Dimmer from scratch

Also these should have much less RF than household dimmers. Household dimmers (most anyway) lowed the voltage by clipping the AC sign wave, so you end up with a sort of square wave, and LOTs of harmonics. Motors HATE square waves so motor controls are usually either Auto transformers or are made to output something close to a sign wave, very few harmonics.
SK
 
Ahh, that makes sense. Thanks for clearing that up for me.


Noiz2 said:
It's listed as 15 amps. In the US that translates to roughly 1500 watts. If you ran it at 250 Volts 15 Amps you would get higher wattage, but do your lights run at 250?

So while your math is correct I don't think it makes a practical difference since your still at ~ 1500 Watts if your running 120.
SK
Click to expand...
 
Dimmers

Dimmers

Invito said:
The Voltage capacity is listed as 250 VDC and the Amp capacity at 15 amps. Using the following equation, shouldn't the watt capacity be 3750w?

Amps x Volts = Watts

I'm probably forgetting something, hence the reason you listed the capacity at 1500w.

Thanks. Great find!
Click to expand...

The Dimmer may be rated at 15 Amps, but that is the Maximum Current the Triac ( two thyristors Back to Back) can handle. ( with it's supplied heat Sink)

That means in the US the dimmer can handle around 1500 Watts, but in the UK because the mains Voltage is 230, the same dimmer could handle 3000 Watts, as the mains voltage is roughly twice as much.
 
Just confirming...

Just confirming...

KHendrix2 said:
$47 is a pretty good deal, but here's a little secret that will give you a 1500 watt dimmer for less money and no labor:

http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=43060

I have three of these and they work great.
Click to expand...

Since it's been 4 years since this link was posted...I wanted to make sure it still links to the same thing. Is this the item you were talking about?:

[FONT=arial, sans-serif]Router Speed Control

[/FONT]
43060.gif
 
THe ones I use are a different color, but yep that's them. Get em from Harbor freight and they are awesome.
 
It's true, these guys work ok for a lot of stuff, in fact I do own 3 of them.... but they have very terrible control as opposed to "real" film production dimmers... aka magic gadgets... but these are def a good start and cheap.
KHendrix2 said:
$47 is a pretty good deal, but here's a little secret that will give you a 1500 watt dimmer for less money and no labor:

http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=43060

I have three of these and they work great.
Click to expand...
 
syncman said:
The Dimmer may be rated at 15 Amps, but that is the Maximum Current the Triac ( two thyristors Back to Back) can handle. ( with it's supplied heat Sink)

That means in the US the dimmer can handle around 1500 Watts, but in the UK because the mains Voltage is 230, the same dimmer could handle 3000 Watts, as the mains voltage is roughly twice as much.
Click to expand...
Be careful about "lighting these up", folks, with too much current.

I suspect that they are "heat dissipation limited", so 15 amps at 240V into a resistive (lamp) load might make your control glow brighter than your bulbs. If the thing is getting way too hot to touch, you're overloading it. Fire in your venue or on your set is the last lighting trick you want to display!

It's fine to experiment and try to cut corners sometimes ... but you must use common sense about things getting TOO HOT. Also, you must watch it at different settings. Settings in the mid range to upper mid range is likely where it will dissipate the most heat.

An engineer.
 
On my way now to get one from harbor freight, just called and in stock!

Thanks for the idea, this helps out big time!


dcarbetta said:
Since it's been 4 years since this link was posted...I wanted to make sure it still links to the same thing. Is this the item you were talking about?:

[FONT=arial, sans-serif]Router Speed Control

[/FONT]
43060.gif
Click to expand...
 
Works like a charm!

With my 650watt light, its a smooth range of brightness and works like it should!

:dankk2:
 
Last edited:
j said:
Yes, it is so much cheaper to do it yourself:

Dimmer <$4
metal box<$1
face plate<$1
extension cord ~$5
caps and wire clasps <$1

Cut they extension cord in half, and wire the ends to the dimmer leads per the directions in the dimmer box, cap it off, put it in the metal outlet/switch box, add a face plate, and voilla! You have what is refered to in the industry as a "hand squeezer" or dimmer box. I like to keep 4 of them in my kit. Very handy, and very cheap.

-j
Click to expand...
if you are going to hold the dimmer DON'T use metal if you screw up you are fried use the plastic ones (non conductors)
 
aafilmproductions said:
if you are going to hold the dimmer DON'T use metal if you screw up you are fried use the plastic ones (non conductors)
Click to expand...

i made mine out of metal so they would last longer on set. i haven't shocked my self by using them yet. plus if you are just using normal house hold power like 20 amps your not going to fry your self. don't get me wrong it will surprise you but it probably wont even burn. at least thats what i now from my experience.
 
zakart said:
i made mine out of metal so they would last longer on set. i haven't shocked my self by using them yet. plus if you are just using normal house hold power like 20 amps your not going to fry your self. don't get me wrong it will surprise you but it probably wont even burn. at least thats what i now from my experience.
Click to expand...

Metal is also better at sinking the heat from the dimmer (which will extended its life). And if you connect the green-wire-ground coming in and going out, there is no more danger of shock than from any other piece of electrical equipment.
 
didn't find this when searching dimmer but after being pointed toward Harbor Freight i searched them and wow that saves some hassle thanks
 
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