Help to modify Osram Dot-It LED to mains

Newby to this forum, thanks in advance.

I have several (6) Osram Dot-It Linear LED lights. All are identical with 3 LED's and battery powered 3 x 1.5v totaling 4.5v. The 3 LED's are in parallel and there is a resistor (looks like 24ohm) in series.

I wish to install these in a display cabinet and be run of mains power in Australia 240v. Is this possible with an of the shelf plug pack transformer with 4.5v output???

Any advice would be appreciated, thanks.

Garrob said:

Newby to this forum, thanks in advance.

I have several (6) Osram Dot-It Linear LED lights. All are identical with 3 LED's and battery powered 3 x 1.5v totaling 4.5v. The 3 LED's are in parallel and there is a resistor (looks like 24ohm) in series.

I wish to install these in a display cabinet and be run of mains power in Australia 240v. Is this possible with an of the shelf plug pack transformer with 4.5v output???

Any advice would be appreciated, thanks.

Click to expand...

Yes, you can actually use those cheap cellphone
charger plugs. Most are meant to run from 110-220v
out of the box. Take a trip down to your local cellphone
store. Ask them for an extra adapters that they may
have lying around from demos and such. You could
probably pick them up for pretty cheap.
The resistor values can be calculated here:
http://led.linear1.org/led.wiz


Robert M.

I'd offer to design the order in which you connected all the LED's, but it looks like that site has it all under control, mainly just because it's asking for the figures that I would.

When you purchased the LED's you should have a piece of paper that came with them, it is a data sheet for the LED, it should specify anything you need to know. Otherwise, you may be able to look that up on the website of the company that you got them from(e.g. tandy).

Old mobile phone chargers are a very good source of a small amount of power. However if that avenue doesn't work, you can also go to Tandy or ****Smith Electronics and purchase adapters for somewhere around $20.

Good luck.

Thanks Robert,

Does this mean if I get a 240vAC / 4.5v DC plug pack I don't have to modify the Osram Dot It LED lamp?

Thanks Hazman for your offer.

The only info I have on the Osram Dot It 3x LED lamp is that it consumes .3 of a watt. It only has one resister in the unit which I think is 24ohms.

Thanks again.

Garrob said:

Thanks Hazman for your offer.

The only info I have on the Osram Dot It 3x LED lamp is that it consumes .3 of a watt. It only has one resister in the unit which I think is 24ohms.

Thanks again.

Click to expand...

Just replace that 24ohm resistor with a 100ohm
one of about 1/2 watt and should be just fine
when running from a 5v adapter. Or, if you get a
12v adapter, setup the leds in series and use a
120ohm 1/2 watt resistor.

www.Digikey.com is a good source for parts too :twothumbs


Robert M.

Thanks again Robert, you have been very helpful.

Garrob said:

Thanks again Robert, you have been very helpful.

Click to expand...

Sure Thang! :twothumbs