Re: [CAD_CAM_EDM_DRO] Re: Power supply for Servos - Energy dump and such - UR...
Posted by
Stephen Wille Padnos
on 2005-02-19 19:41:25 UTC
turbulatordude wrote:
running the dump LED from the comparator, the power will come from the
+12V rail, so you'll still need to change the 6.8k resistor to allow
more current. Thinking about it, that's a wash anyway, because the
current limiting resistor would have to be 3.9k, 2W (assuming an 80V
supply, ~20mA LED) if the LED were run directly across R7. So just
change the 6.8k to a 1.5k 5W (a 45mA supply, for 2 LEDs @ 20mA + the
comparator), and make sure the zener is at least 1/2 W. (when the load
dump LED is off, 20mA would be going through the "active" LED, a small
amount will be used by the op-amp and associated circuitry, and the
zener will be sinking roughly 25mA at 12V = 300mW, 350 is closest and
500 gives a little safety margin). A lower voltage supply would need a
lower value resistor, but the same zener diode.
>I'm adding an LED for the main AC power and one to show the energyThat's an excellent idea.
>dump.
>
>for the dump, I will add a cap to the line so the LED will light,
>then fade. I think it might just flash too fast to see otherwise.
>
>
>There is an unused output of the comparitor, so the output of theI'm not sure I understand what you mean. Even if you're planning on
>comparator can be used when the mosfet is powered to indicate the
>dump without having to make allowancs for the LED.
>
>
running the dump LED from the comparator, the power will come from the
+12V rail, so you'll still need to change the 6.8k resistor to allow
more current. Thinking about it, that's a wash anyway, because the
current limiting resistor would have to be 3.9k, 2W (assuming an 80V
supply, ~20mA LED) if the LED were run directly across R7. So just
change the 6.8k to a 1.5k 5W (a 45mA supply, for 2 LEDs @ 20mA + the
comparator), and make sure the zener is at least 1/2 W. (when the load
dump LED is off, 20mA would be going through the "active" LED, a small
amount will be used by the op-amp and associated circuitry, and the
zener will be sinking roughly 25mA at 12V = 300mW, 350 is closest and
500 gives a little safety margin). A lower voltage supply would need a
lower value resistor, but the same zener diode.
>Dave- Steve
>
>
Discussion Thread
wanliker@a...
2005-02-19 13:07:58 UTC
Power supply for Servos - Energy dump and such - UR...
Stephen Wille Padnos
2005-02-19 13:30:18 UTC
Re: [CAD_CAM_EDM_DRO] Power supply for Servos - Energy dump and such - UR...
wanliker@a...
2005-02-19 13:55:20 UTC
Re: [CAD_CAM_EDM_DRO] Power supply for Servos - Energy dump and such - UR...
cnc_4_me
2005-02-19 14:11:26 UTC
Re: Power supply for Servos - Energy dump and such - UR...
Stephen Wille Padnos
2005-02-19 14:36:42 UTC
Re: [CAD_CAM_EDM_DRO] Power supply for Servos - Energy dump and such - UR...
turbulatordude
2005-02-19 15:34:24 UTC
Re: Power supply for Servos - Energy dump and such - UR...
Stephen Wille Padnos
2005-02-19 19:41:25 UTC
Re: [CAD_CAM_EDM_DRO] Re: Power supply for Servos - Energy dump and such - UR...
turbulatordude
2005-02-19 21:16:13 UTC
Re: Power supply for Servos - Energy dump and such - UR...
Polaraligned
2005-02-21 04:56:23 UTC
Re: Power supply for Servos - Energy dump and such - UR...
R Rogers
2005-02-21 05:48:48 UTC
Re: [CAD_CAM_EDM_DRO] Re: Power supply for Servos - Energy dump and such - UR...
turbulatordude
2005-02-21 07:12:06 UTC
Re: Power supply for Servos - Energy dump and such - UR...
Polaraligned
2005-02-21 08:48:45 UTC
Re: Power supply for Servos - Energy dump and such - UR...
turbulatordude
2005-02-21 09:27:58 UTC
Re: Power supply for Servos - Energy dump and such - UR...
Jon Elson
2005-02-21 11:05:53 UTC
Re: [CAD_CAM_EDM_DRO] Re: Power supply for Servos - Energy dump and such - UR...
turbulatordude
2005-02-21 11:18:38 UTC
Re: Power supply for Servos - Energy dump and such - UR...
Polaraligned
2005-02-21 11:23:23 UTC
Re: Power supply for Servos - Energy dump and such - UR...
turbulatordude
2005-02-21 12:01:03 UTC
Re: Power supply for Servos - Energy dump and such - UR...
Mariss Freimanis
2005-02-21 14:43:18 UTC
Re: Power supply for Servos - Energy dump and such - UR...
Polaraligned
2005-02-22 13:53:39 UTC
Re: Power supply for Servos - Energy dump and such - UR...
R Rogers
2005-02-22 14:13:34 UTC
Re: [CAD_CAM_EDM_DRO] Re: Power supply for Servos - Energy dump and such - UR...