12v wireless dimming

[peter]

Alright, heres the problem...

 

For a forthcoming production, the director has two scenic trucks which rotate on stage, move around the stage and swap positions. As such, trailing cables are a big no-no. He wants a few internal lights within the structure of the trucks, so my thoughts are MR16 style effects.

 

This problem really divides up into two.

1) How to get power to the truck

My main thought with this is to use a 12v car battery (300Ah or more). I could then either

a. run an inverter and 'conventional' 230v dimmers (I have alphapacks available) / 12v transformers

b. run a specialised 12v dimmer - if one exists. I only need 3 ways of dimming on each truck (two trucks)

 

2) How to control the dimmers

DMX over WLAN is very expensive, as far as I know DMX can't be sent over radio-mic frequencies. I have a demux available for the project, so is there a way of sending +10v control signals over radio?

 

Can anyone help me out here? I've got till January for the production, but I have a feeling this will take a while to get the effect working reliably. The show runs for two weeks, so longevity in the effect is also needed. Fairly limited budget, but I might be able to beg for more if the effect would be really reliable.

 

And before anyone points it out, I know of Howard Eaton's 12v wireless dimming product, but its a bit too pricy for this project.

 

Thanks in advance for replies. I'll provide any furthur information I can.

 

 

 

 

Peter

[Brian]

Hmmm

 

You'd need to control it manually but how about using a cheap model radio control kit? With a bit of simple mechanics you should be able to make the servo move either a rotary pot or a slide pot.

 

How much lamp power do you need on each truck?

[peter]

Roughly, 3 x 50w birdies.

[Matt]

as brain said

 

with remote control cars (the ones you buy out the box such as tamiya) they copme with a mechanical speed control, this relies on resistance through a big resistor...

 

dunno how it would handle with one 50w lamp on it let alone 3, but it certainly is a good idea plus the radio controls are moderateley expensive aswell, and the recievers for them run on 7.2v so you might have a problem there, you have a choice ot 27mhz, 35mhz or 40 mhz when you dont wanna spend over £100 ona decent radio control plus u'll have to find a way of setting it at one point, once you remove your finger from the control, it returns to 0 :)

 

regarding the lamps, you can get those 12vdc halogen ones and 10, 25 and 50w like the ones used in kitchens - could be cool

 

get some pics when its done :blink: would love to see it

 

...and yes one does race remote control cars (quite sad really when you win every race, no competition for the fastest car <_< )

 

Matt.

[James]

as brain said

<{POST_SNAPBACK}>

 

Is this a compliment to Brian?

 

James

[Matt]

yes it is, sorry james here's your £50 back, ever wonder why I have this award, he was perfectly right about using the remote control car kit type of thing, it is possible, I just had a look at the current ratings on my "speed controller" it has max of 1200 amps surge and nominal 580 - one thinks this is a but ott for something that runs on 7.2vdc but hey running a few 50watt lamps off of it is possible no...

 

...500w fresnel of mine is at about 2.5 amps but thats ac :) theres my theory poggered now...

 

I'll go back to my cupboard now... <_<

[David]

Maplins do a 2 channel 13amp radio dimmer for about £15. You could run it of an inverter and a 12v battery.

[Matt]

sounds cool, might be useful for me to buy some eventhough I dont need then atm - very useful indeed

[Tomo]

Your best bet is probably R/C car technology.

You can get good quality 40MHz radio control systems for around 100 quid, and there is a large selection of extra-low voltage speed controllers available.

 

Look into aircraft and boat speed controllers, as single-direction units are all you need and they are cheaper than the car bi-directional units.

 

Do NOT be tempted by the cheap 27MHz units as they are very unreliable, and 35MHz ones are not licenced for use in surface applications - flying stuff only.

 

If I was building this, I would use a 6-channel transmitter, and a pair of 6-channel receivers - one for each truck. That way you use less of the 40MHz spectrum, and it's easier to ensure you have a free band when you come to performing the show. (Plus you can repatch)

However, you may find it easierto get a pair of 3-channel Tx/Rx pairs, if only because it's easier to convert them into a fader bank - can't have a GM unfortunately due to the way the Txs work inside.

 

Unfortunately there's no easy way to control them via DMX - it could be done with some electronically controlled variable resistors and a PIC or two, but manual faders are much easier.

 

At the truck end, you plug three suitably-rated single-direction speed controllers into the Rx, and connect them up to your12v battery power supply and lamp(s).

 

Turn everything on, trim the faders, and away you go.

[P. Funk]

I seem to remember a company called X10 doing some home lighting automation products, possibly including a wireless dimming system. That runs on 230V though IIRC

 

And also, now that I think of it, a company at the PLASA show last year had a kit of par56 cans and 'remote control' (IR) dimming as a package - possibly showtec or someone similar... which might be worth looking into. Possibly a bit expensive though.

[broadcast_techie]

maplin do the various velerman kits (spell checker off)

 

I seem to recall some dimming function (does it have to dim?) (switch would be a h*ll of a lot easier)

 

for about £30 I got a keyfob type remote from cpc, a couple of relays and box from maplin and made myself a remote for a frog (fairly good range, I can sit anywhere in the hall and effectivly press the 'go' buttons - only downside is you occassionally see me running!!)

 

just a thought or two....

 

Kristan

[colinmonk]

Have you talked to HELL to see if you can get a bit of a deal out of them? There people are very good, and are usually quite helpful...

 

Its probably also one of the most reliable ways of achieving your effect... rather than bodging something together

[Jivemaster]

Beware the inverter route, most inverters output an odd waveform, nothing like a sine wave more a PWM multi zero crossing square wave, with a warning that some clocks will run at three times speed!!! Having said that Maplin were ofloading some so called sine wave ones recently.

[gareth]

Maplin were ofloading some so called sine wave ones recently.

They were advertising them, yes - but they don't actually have any to sell. <_<

 

I wanted to get one myself, but none of the four Maplin stores within easy driving distance of me were expecting stock until the first week of October (by whch time they'd be back up to their normal price, which is twice the price advertised in the sale brochure), and even the website was showing "out of stock for at least 28 days". Oddly enough, they were showing that they did have stock of exactly the same model at full, non-sale (double) price ........

 

Sorry, a little :), but one thing that really bugs me is companies who advertise something in a sale at a really good price, but then turn out to not actually have any of them in stock and it was just a ruse to get you onto their website or into their stores at which point they can try to flog you something far more expensive.

[V*L Ben]

plus u'll have to find a way of setting it at one point, once you remove your finger from the control, it returns to 0 <_<

 

 

<{POST_SNAPBACK}>

 

on cheap Aeroplane remotes the 'throttle' doesnt return to 0 when you let go