daft question on LED indicators and high VDC

[dsc]

Umm.. the first way is correct - the resistor and zener are interchangeable in this diagram, just different ways to drop the volts.

The second is unnecessary as uses two components when one will do. LED doesn't need regulated supply so the zener is unnecessary.

The second provides a solid voltage on the zener regardless of the load, which is different to a standard resistor divider. I'll go with the first one, it's 36p for the Zener vs. 9p for a resistor but as you said before minimum order quantity is 10 (doesn't really matter as I need to go over £5 for the order anyway).

Those 7seg displays are pretty neat considering the voltage range on them. I'll have to stick with a small LED indicator as I'm tight on space as it is.

T.

[dsc]

Just a quick update, I've tried both the resistor and the diode, both get rather hot, although the diode seems to handle it better. Done some checks with a TC and the resistor sits at around 80degC whereas the diode goes up to around 60deg. The ideal solution would be to change the PSU to a 48VDC, but with the current solution costing less than a pound I don't think I'll bother:)

T.

[Binary]

Hi you say your wanting to connect a LED to a 68VDC PSU. you can use a LED with a resistor in series If your machine is on permanently, I would suggest to drop the current to 15mA, LEDs work at 20mA but run constant shortens their life expectancy. If your LED is a 24 volt version check the spec on it the resistor already in situ may already drop the current to the LED to 12~15mA, just remember the power supply you are connecting to will either be PWM or linear my guess PWM either way the voltage (68VDC) will be constant