Electrical Help Anyone??

[Turtle91]

Hi all,
I'm having some difficulty getting my power supply circuit to work. Well, it works, but it gets so hot that I'm wondering if there is a better way of doing it. I actually burned my fingers on the heat sink so forgive me if I type too slow...

I have a 19.5V 4.5Amp laptop power supply that I am using to power my LED's, cameras and LCD displays.

The LED's are being driven by a 3023 1000mA Buckpuck. This will accept the 19.5 volts directly and goes from .035 Amps at dim light, to just under 0.5 Amps at full bright.

The 2 LCD displays draw 9.5 volts and use just under 0.5 Amps each.

The 2 Canon A495 cameras run at 3.15V and each draw a range up to about 0.75 Amps depending on the functions being used (idle, playback, half-shoot, full-shoot)

I was able to use the LM317 variable voltage regulator to drop the voltage down from 19.5 to 9.5 and then 3.15.



The problem is that the - very large - heat sinks I am using (scrounged from a PC power supply) are getting REALLY hot! (25 watts dissipation on VR1, and about 9 watts on VR2)

Does anyone know how I can shed the voltage between each section while still allowing the required amperage to pass through? Or is there a better way to set up this whole power issue??

Thanks for any help,
Dion

[daniel_reetz]

Unfortunately that power dissipation is just the reality of working with analog voltage regulators.

You have a few options.

1. You can use a separate power supply for your BuckPuck and your cameras. Match the supply to the BuckPuck specs for your LEDs.

2. You can use a DC-DC converter to power your cameras. They regulate current and voltage in the same way as the BuckPuck, and don't have the heat issues of analog regulators. You can make them out of phone chargers: http://hackaday.com/2010/09/12/building ... converter/

[Turtle91]

2. You can use a DC-DC converter to power your cameras. They regulate current and voltage in the same way as the BuckPuck, and don't have the heat issues of analog regulators. You can make them out of phone chargers: http://hackaday.com/2010/09/12/building ... converter/

Wow! that's exactly what I was looking for! I wonder why the "knowledgable and friendly" customer assistance expert at my local electronics store pointed me towards voltage regulators instead??

Just another reason I appreciate this forum!!


Thanks!
Dion

[daniel_reetz]

No problem Dion, I did the same thing with my first LED rig, all analog. It was SHOCKING to me to see how much power it wasted as heat.

FYI, you can usually get obsolete cell-phone chargers at dollar stores. I bought 15 or 16 of them last time I was at Big Dollar, just because they are so useful. You'll need to swap a resistor or so. In my experience you have to set the voltage just a little high because it sags under load. Also you can double them up if they can't handle the .5A draw per device. I recommend one per device at least.