light painting tips - Page 4

Unclehaggz · 18 Jul 2015, 11:07 am

Light Knight wrote:Just a (possibly stupid) question on powering LED strip lights (I'm not an electrician). How do you work out the battery requirements for powering a set amount of LED strip? Would I be right in saying that you need the battery holder/number/types of batteries to produce the required voltage for the LED strips (e..g 4 AAs in series would be 6V)? Also, how do you then work out the number of batteries required to run a certain amount of LED strips for a decent amount of time? Thanks for any answers.

This is a unique question, namely all LED's have differing forward voltage's (amount required to led on), normally most LED's are in the range of 1.5-3V, however some newer cree's are higher, depending on manufacturer.
One thing led's have to have is a current limiting resistor, normally I work on a max current of .02A if you don't have a resistor the LED will blow! Some simpler devices use the internal impedance of the battery as the resistor/current limiter, namely if the battery is a 2032 it will only allow .032A to flow!!

In answering your question if you have a LED strip who's LED's forward voltage is 1.5V and they use .02A we use Ohms law V=IR so 1.5=.02*R, rea-arranging the formula R=V/I, this will give 1.5/.02=75 Ohms (resistor). If we assume we have a supply current maximum of 1A then we simply divide 1 by .02 = 50 Led's !!!!

Because we use a dropper resistor and limit the current we can safely use any DC supply from 1.5-24V as Ohms law will provide the required voltage drop across the resistor.

Hope it makes sense!!

UH

Light Knight · 18 Jul 2015, 4:33 pm

Unclehaggz wrote:
Light Knight wrote:Just a (possibly stupid) question on powering LED strip lights (I'm not an electrician). How do you work out the battery requirements for powering a set amount of LED strip? Would I be right in saying that you need the battery holder/number/types of batteries to produce the required voltage for the LED strips (e..g 4 AAs in series would be 6V)? Also, how do you then work out the number of batteries required to run a certain amount of LED strips for a decent amount of time? Thanks for any answers.
This is a unique question, namely all LED's have differing forward voltage's (amount required to led on), normally most LED's are in the range of 1.5-3V, however some newer cree's are higher, depending on manufacturer.
One thing led's have to have is a current limiting resistor, normally I work on a max current of .02A if you don't have a resistor the LED will blow! Some simpler devices use the internal impedance of the battery as the resistor/current limiter, namely if the battery is a 2032 it will only allow .032A to flow!!

In answering your question if you have a LED strip who's LED's forward voltage is 1.5V and they use .02A we use Ohms law V=IR so 1.5=.02*R, rea-arranging the formula R=V/I, this will give 1.5/.02=75 Ohms (resistor). If we assume we have a supply current maximum of 1A then we simply divide 1 by .02 = 50 Led's !!!!

Because we use a dropper resistor and limit the current we can safely use any DC supply from 1.5-24V as Ohms law will provide the required voltage drop across the resistor.

Hope it makes sense!!

UH

Thanks for the explanation, much appreciated. It's a long time since I covered basic electrical physics since school and uni (I only use 150kV equipment at work).

I was asking as I came across this in Bunnings http://www.arlec.com.au/detail-2/?de=ALD011 for $29.
The 4 strip light segments (total 1200mm length) could be connected and stuck to a stick for a potentially easy to make white light painting wand with 36 LEDs. Whilst it is meant to be mains operated via a 12V transformer, when in the packet it is connected to "try me" circuit that consists of a push button and a case with a 12V A23 battery. I was thinking that continuing to use the "try me" circuit, but replacing the single 12V A23 battery with a battery case with 8AAs in series, which would provide 12V and theoretically power the device for much longer. However, I assume I am not taking into account the resistor requirements here unless one is already incorporated? It should be noted that in the packet the 12V A23 battery is only running one of the 4 strip sections, the others are not connected.

They also have a colour changing version as well for $39 http://www.arlec.com.au/detail-2/?de=ALD012 .

Unclehaggz · 18 Jul 2015, 6:11 pm

Light Knight wrote:
Unclehaggz wrote:
Light Knight wrote:Just a (possibly stupid) question on powering LED strip lights (I'm not an electrician). How do you work out the battery requirements for powering a set amount of LED strip? Would I be right in saying that you need the battery holder/number/types of batteries to produce the required voltage for the LED strips (e..g 4 AAs in series would be 6V)? Also, how do you then work out the number of batteries required to run a certain amount of LED strips for a decent amount of time? Thanks for any answers.
This is a unique question, namely all LED's have differing forward voltage's (amount required to led on), normally most LED's are in the range of 1.5-3V, however some newer cree's are higher, depending on manufacturer.
One thing led's have to have is a current limiting resistor, normally I work on a max current of .02A if you don't have a resistor the LED will blow! Some simpler devices use the internal impedance of the battery as the resistor/current limiter, namely if the battery is a 2032 it will only allow .032A to flow!!

In answering your question if you have a LED strip who's LED's forward voltage is 1.5V and they use .02A we use Ohms law V=IR so 1.5=.02*R, rea-arranging the formula R=V/I, this will give 1.5/.02=75 Ohms (resistor). If we assume we have a supply current maximum of 1A then we simply divide 1 by .02 = 50 Led's !!!!

Because we use a dropper resistor and limit the current we can safely use any DC supply from 1.5-24V as Ohms law will provide the required voltage drop across the resistor.

Hope it makes sense!!

UH
Thanks for the explanation, much appreciated. It's a long time since I covered basic electrical physics since school and uni (I only use 150kV equipment at work).

I was asking as I came across this in Bunnings http://www.arlec.com.au/detail-2/?de=ALD011 for $29.
The 4 strip light segments (total 1200mm length) could be connected and stuck to a stick for a potentially easy to make white light painting wand with 36 LEDs. Whilst it is meant to be mains operated via a 12V transformer, when in the packet it is connected to "try me" circuit that consists of a push button and a case with a 12V A23 battery. I was thinking that continuing to use the "try me" circuit, but replacing the single 12V A23 battery with a battery case with 8AAs in series, which would provide 12V and theoretically power the device for much longer. However, I assume I am not taking into account the resistor requirements here unless one is already incorporated? It should be noted that in the packet the 12V A23 battery is only running one of the 4 strip sections, the others are not connected.

They also have a colour changing version as well for $39 http://www.arlec.com.au/detail-2/?de=ALD012 .

The strips will already have surface mounted resistors on it, they are differing values according to the LED colour! but yes you can power them with either the A23 battery of something a little larger like a 12V1.5Ahr that easily fits into a bum bag or similar (thats why my backpack weighs so much.

UH

Light Knight · 18 Jul 2015, 8:13 pm

Unclehaggz wrote:
Light Knight wrote: Thanks for the explanation, much appreciated. It's a long time since I covered basic electrical physics since school and uni (I only use 150kV equipment at work).

I was asking as I came across this in Bunnings http://www.arlec.com.au/detail-2/?de=ALD011 for $29.
The 4 strip light segments (total 1200mm length) could be connected and stuck to a stick for a potentially easy to make white light painting wand with 36 LEDs. Whilst it is meant to be mains operated via a 12V transformer, when in the packet it is connected to "try me" circuit that consists of a push button and a case with a 12V A23 battery. I was thinking that continuing to use the "try me" circuit, but replacing the single 12V A23 battery with a battery case with 8AAs in series, which would provide 12V and theoretically power the device for much longer. However, I assume I am not taking into account the resistor requirements here unless one is already incorporated? It should be noted that in the packet the 12V A23 battery is only running one of the 4 strip sections, the others are not connected.

They also have a colour changing version as well for $39 http://www.arlec.com.au/detail-2/?de=ALD012 .
The strips will already have surface mounted resistors on it, they are differing values according to the LED colour! but yes you can power them with either the A23 battery of something a little larger like a 12V1.5Ahr that easily fits into a bum bag or similar (thats why my backpack weighs so much.

UH

Thanks for the info again. I think 8 alkaline AAs in series would be 12V and 2Ah. I'll give it a go when I get the chance (probably at 3am with a screaming baby over my shoulder), though I'm sure it'll be a long way off the standard of Haggz Industries Light Painting Tools.

Unclehaggz · 21 Jul 2015, 9:45 pm

I have started a Journal for this here :- viewtopic.php?f=50&t=3562

UH

Light Knight · 25 Jul 2015, 8:43 pm

The following is my first attempt at making a light painting tool - a warm white light LED wand.

Light Painting Tool Test by Light Knight, on Flickr

Components (so far):
- Arlec Warm White LED Strip from Bunnings (three out of four 30cm strips utilised) - these have a sticky back for fixing onto surfaces.
- Black Electrical Tape from Bunnings - to protect connections and soldering.
- 1200mm wooden extrusion from Bunnings - the stick!
- 8AA Battery Holder from Jaycar - this is required to bring the voltage up to 12V required by the LEDs. Note: due to 9W rating of the three strips used, a single A23 12V battery wouldn't last long.
All up, approx. $40.

As the LED strip package included the +ve/-ve connecters, resistors for each LED, connectors between strips, and the on/off switch, then wire stripping and soldering was only required to replace the power supply with the 12V battery supply. Soldering was quite successful (i.e. didn't burn myself or the house down) given that I haven't soldered for 25 years!

The next step is to duct tape the switch and batteries to the wooden stick, and replace some of the black electrical tape with white tape to make it less obvious in photos where the joints between strips are. I'll post another photo of the finished product. Then it'll be time for photos of it in action.

Bunnings also sell a RGB strip with IR controller (similar to the one in UH's post) for $10 more. That might be version 2.

Unclehaggz · 26 Jul 2015, 11:55 am

Light Knight wrote:The following is my first attempt at making a light painting tool - a warm white light LED wand.

Light Painting Tool Test by Light Knight, on Flickr

Components (so far):
- Arlec Warm White LED Strip from Bunnings (three out of four 30cm strips utilised) - these have a sticky back for fixing onto surfaces.
- Black Electrical Tape from Bunnings - to protect connections and soldering.
- 1200mm wooden extrusion from Bunnings - the stick!
- 8AA Battery Holder from Jaycar - this is required to bring the voltage up to 12V required by the LEDs. Note: due to 9W rating of the three strips used, a single A23 12V battery wouldn't last long.
All up, approx. $40.

As the LED strip package included the +ve/-ve connecters, resistors for each LED, connectors between strips, and the on/off switch, then wire stripping and soldering was only required to replace the power supply with the 12V battery supply. Soldering was quite successful (i.e. didn't burn myself or the house down) given that I haven't soldered for 25 years!

The next step is to duct tape the switch and batteries to the wooden stick, and replace some of the black electrical tape with white tape to make it less obvious in photos where the joints between strips are. I'll post another photo of the finished product. Then it'll be time for photos of it in action.

Bunnings also sell a RGB strip with IR controller (similar to the one in UH's post) for $10 more. That might be version 2.

Great effort LK, can't wait for the results!!!!:)
UH

Light Knight · 28 Jul 2015, 8:39 pm

Since the last photo:
- I've replaced the black tape over the connectors with white tape, to make the light source seem more seamless.
- I've mounted the switch, battery holder, and tidied up the wires using black electrical and duct tape. The battery holder has been taped to make changing batteries fairly easy (though requires carrying more duct tape if battery changes are required in the field). These were all mounted with ergonomics in mind - single handed holding and on/off switching.

Light Painting Tool - Completed by Light Knight, on Flickr

I'm quite happy with the results. Now I just need to get out of the house and use it!

Unclehaggz · 28 Jul 2015, 9:47 pm

Light Knight wrote:Since the last photo:
- I've replaced the black tape over the connectors with white tape, to make the light source seem more seamless.
- I've mounted the switch, battery holder, and tidied up the wires using black electrical and duct tape. The battery holder has been taped to make changing batteries fairly easy (though requires carrying more duct tape if battery changes are required in the field). These were all mounted with ergonomics in mind - single handed holding and on/off switching.

Light Painting Tool - Completed by Light Knight, on Flickr

I'm quite happy with the results. Now I just need to get out of the house and use it!

Looking good LK, try it in the garden and see what results you get:)

UH