REALLY?:Are constant current regulators (DC) dangerous?

[constantine_a_f]

Is it dangerous (lethal or painful) to work with constant current regulators and power drives like this?

http://www.luxeonstar.com/700mA-Ext-Dimmable-BuckPuck-Driver-PCB-Mount-p/3021-d-e-700.htm

Would touching the output of this cause any threat?

I plan on using this with a 9.6 (8AA) V battery to power one high power led at 700mA. Could making a mistake (I have no experience) or not insulating the led probably lead to an accident? I will use it as a headlight.


Thanks

 

[DM51]

Welcome to CPF, constantine_a_f :)

Your question is about electronics and we have a separate sub-forum for that, so I'll move it there.

 

[constantine_a_f]

Thanks,

I am not really familiar with the forum yet, so sorry for the honest mistake.

 

[ArmyTek]

Is it dangerous (lethal or painful) to work with constant current regulators and power drives like this?

Constant current electronics is normal solution for LED supply.

 

[uk_caver]

Is it dangerous (lethal or painful) to work with constant current regulators and power drives like this?

A constant-current buck driver has a maximum output voltage lower than the input voltage, and so touching the output should be at least as safe as touching the input power connections.

Though it's a constant current driver, that doesn't mean that it will always ensure its design current passes through the load whatever the load is.
Effectively, it's a current-limited output, from a driver that is designed to operate consistently at that limit, but where the current will be some way below the limit if the load has a high resistance (like a human touching the wires).

A constant-current boost driver could produce an output voltage greater than the input voltage, but even then, such drivers will often have a maximum output voltage which is safe.

 

[Mr Happy]

If this question relates to a comment I made in another thread, I used the word dangerous in relation to delicate electronics. Most electronic devices (not LEDs) are designed to operate from a voltage regulated supply. If you improperly connect such a device (like a microprocessor control board) to a constant current, or current regulated supply, you stand a very good chance of destroying the electronics.

Most battery operated equipment does not generate sufficient voltages to be a problem for humans, but if you happen to have a mains operated driver that is designed perhaps for a string of 20 LEDs in series, then I would watch out.

Lastly, in another context, airfield lighting systems make use of constant current supplies and use bulbs rated for a fixed current rather than a fixed voltage. These systems of course have a lot of power behind them and must be considered very dangerous, just like other high voltage systems.

 

[VidPro]

I have got a nice shock off of a high voltage LED boost driver, was not "dangerous" by any means, but i knew it was working :-) it was capable of boosting to 70V or something.
and it must have been really pulsing too , instead of very clean dc power , cause it felt like tiny bits of ac. didnt seem to have much current though compared to a few other encounters i have had with wall sockets and drivers. for real excitement try florescent drivers, or zenon strobe drivers, those will wake you up :-)

 

[constantine_a_f]

I understand that Ohm's law is what makes it safe to use. I thought that the device would maintain 700 mA through any circuit (even the human body), but apparently I was wrong. Thanks for the answers.

 

[HarryN]

I understand that Ohm's law is what makes it safe to use. I thought that the device would maintain 700 mA through any circuit (even the human body), but apparently I was wrong. Thanks for the answers.

The constant current drivers will "try" to do this. Ohms law is still obeyed, though.

In a "step down / buck" type, the output current will be constant until the maximum output voltage is reached. (which by definition, is less than the battery voltage supply). Example - 12 volt battery = the driver output voltage will adjust to hit the 700ma, but will never go above 12 volts.

In a "step up / boost" type, the same thing is true, except that the maximum output voltage is higher than the battery supply voltage. Example 12 volt battery = driver output voltage will adjust to hit 700ma, until hit hits the max of the driver rating. This can be quite high = 70 volts on some drivers, which is above the inherently safe voltage levels.