Power "on" LED

[Howley]

I have a new PRS standard, 4x8 and like most shopbots I have No LED power on indication light. Has anyone safely added a power on indication light?
5 or 24 volts?
I do have a background in electronics and know that just adding an LED to the wrong location without the proper resister in line can cause problems and loads on circuits.

Any ideas?

Thanks in advance for any replies!

[richards]

If you keep the forward current to 10mA, an LED should work fine as an indicator. Many LEDs drop 2v, so 5v - 2v = 3v and 3v / 0.010 mA = 300 ohms. Finally, 0.010 mA X 3v = 0.03 watts. For 12v, use a 1,000 ohm, 1/4 watt resistor. For 24v, use a 2.2k, 1/2 watt resistor.

Of course, always check the specs of the LEDs. As a safety precaution, I often add a 1N4001 reverse-biased diode to protect the LED from being hooked up backwards, especially if I use a power supply greater than 5v.

[dana_swift]

For a power on indicator.. I just use the prox switches. The leds are on unless the bolt is under the prox. I just stop the Z carriage about midway so the prox is on when the machine is, that is the morning starting position.

Adding an additional indicator is trivial of course, but the prox switches do the job for me. Mike gave good advise on the current limiting resistor.. follow it!

And I have gone off too late, too tired, and discovered the next morning I never shut it off. Sigh. Maybe this thing really NEEDS a power on. How about power on, reset, and all systems go indicators? Might include "have I zzeroed yet?" indicator. Hmm I can see putting one of those in myself :)

D

[bleeth]

Hey Dana: How about a safety yellow strobe when it's on and a red one with a "back up" beeper when it's running? Think that might drive one around the bend?

[adrianm]

Put a spindle with a VFD on it. You'll be in no doubt whether it's on or off then.

Whether the spindle is actually running or not is another matter entirely at that stage though....

[Brady Watson]

Look down at the big red switch on the control box and see if it is on or off. Standards have a larger switch than the Alphas do.

-B

[Brian Harnett]

I wired my computer table work light off the main switch on the box.

[Howley]

Thanks for the feedback! My control box is facing a wall because of how I had to set it up in my shop, so I can not easily see the big red switch.:p

Any ideas on a safe source inside the PRS Standard control box?
I guess I can take my meter and just probe around?:rolleyes:

How long will I be a "new" member?! Probably as long as I ask stupid questions!:D