12v DC lighting

[Colinrifat]

Hi guys

 

I need some help rigging up a light for a basic job I'm involved in. It needs to be portable so it is going to be supplied from a 12v battery belt with XLR outputs. I need to rig a small light on a boom arm (which will be in a china ball) but it needs to be dimmable. Does it need to be a specific 12v DC lamp and dimmer and if so, what is likely to be the easiest/cheapest way to do it?

 

I'd really appreciate any help that you can give me with this.

[musht]

depends on how big your battery pack is and how long you need it to run for...

 

50W halogen capsule will be nice and bright but at over 4A will eat even Li-Ion batteries quick.

 

20W halogen might give you some balance between run and brightness with halogen colour temp.

 

Probably get similar brightness at about 25% of the power using white LED but colour might be a bit cool, warmer LED available but efficiency goes down a bit.

 

Lot less handling concerns with LED source over hot halogen...

 

Dimming on board or remote, simple PWM dimmer on the battery pack or Theatre Wireless RC4 if remote

 

http://www.theatrewireless.com/

[Colinrifat]

Thanks for that musht. It's a 5.5Ah battery. LEDs might be the best option given the things you have mentioned. The dimmer can be on board so do you no of a PWM that I can buy or is it a case of making one up with some electronic bits>

[musht]

Lot of PWM controllers for model train and RC car markets.

 

No experience of supplier, but easier than veroboarding it:

 

http://www.electronelec.co.uk/acatalog/PWM...hr_42_____.html

 

LED strip or tape stuck, possibly literally, to a Toblerone shape should give you 360 illumination.

[Jivemaster]

What power lamp do you need on the boom?

 

Look at Milford products for interesting boards often DMX related too and there is a DMX to PWM board if you look.

Sadly their site doesn't make for easy linking http://www.milinst.co.uk/

[Colinrifat]

Thanks musht, I'll have a look at that. Jivemaster, it will ideally be about the equivalent of a 60w tungsten lamp so nothing too big.

[dmxtothemax]

If you keep it small and simple,

Such as a led mr16 lamp,

You can get by with using a wire wound pot,

for the dimmer element.

The bigger the lamp,

The more complex the dimmer gets,

Wirewound pots can handle up to 5w.

Even bigger pots such as used in L pads

can handle 20w.

 

Hi guys

 

I need some help rigging up a light for a basic job I'm involved in. It needs to be portable so it is going to be supplied from a 12v battery belt with XLR outputs. I need to rig a small light on a boom arm (which will be in a china ball) but it needs to be dimmable. Does it need to be a specific 12v DC lamp and dimmer and if so, what is likely to be the easiest/cheapest way to do it?

 

I'd really appreciate any help that you can give me with this.

[david.elsbury]

If you keep it small and simple,

Such as a led mr16 lamp,

Another case of Mr dmxtothemax offering advice that is a bit "out" from the requirements of the OP.

What LED MR16 lamp would you recommend that provides the equivalent light output to a 60w tungsten lamp? Let me quote the post above yours, in case you didn't catch it.

 

Jivemaster, it will ideally be about the equivalent of a 60w tungsten lamp so nothing too big.

[dbuckley]

What LED MR16 lamp would you recommend that provides the equivalent light output to a 60w tungsten lamp?

This one??

 

EDISON 6W Led MR16 Bulb 3x2W = 6w, Daylight White, 60W Equivalent

 

Unfortunately, it claims to be non-dimmable. But I'd be tempted to have a looksee at just how non-dimmable it really is...

 

LEDs are getting better every day, it seems...

 

http://ecx.images-amazon.com/images/I/41B0KD+-xjL._SL500_AA300_.jpg

[gyro_gearloose]

You don't say what type of battery you are using, but if it is lead-acid there are some things you need to be aware of. You said your battery is 5.5Ah? If its a lead-acid battery then that figure is a bit mis-leading as it does NOT mean that you will get 5.5 Amps for 1 hour. You'll actually get 5.5 amps over 20 hours, or roughly 0.275 amps per hour for 20 hours.

 

If you increase the load, to 1.1 amps for example, you'd expect the battery to last for 5 hours, right? After all it seems fairly straight forward : if you multiply the load by 4, you divide the total run time by 4. Unfortunately it does not work quite like that. Lead-acid, and to a lesser extent Lithium, batteries are affected by Peukerts Law. The law states that the faster a battery is drained, I.e the greater the load placed on it, the less total power it will provide. So using the 5.5Ah battery as an example, that 1.1A load will drain the battery in less than 5 hours. How long the battery will last depends on its construction.

[adamharman]

What LED MR16 lamp would you recommend that provides the equivalent light output to a 60w tungsten lamp?

This one??

 

I think David E is thinking the same as me, that as the lamp is going in a china ball, then the OP is looking for the equivalent of a 60w tungsten GLS lamp i.e. pretty much 360 degree light output.

 

I think I've seen LED lamps on ebay that do this, made for use in car rear lights which may be suitable. MR16 being reflector lamps aren't going to have the right effect.

[Colinrifat]

Thanks for all the suggestions. I am an electrician but I don't have a great deal of experience with electronics. I got a PWM kit and tried putting it together but I must have gone wrong somewhere because it didn't work! By the look of it, there isn't a ready made dimmer switch that I can buy so I think that I will take the simple option and rig a 12v cfl lamp without a dimmer and just move the light closer or further away! If I've worked it out correctly, the battery should last 3 or 4 hours (11w lamp) which should be fine.