Zack and Zelda - Hybrid vv mods
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Thanks for the info. That all makes sense. I'll have to study that data sheet more and find where that extra .4v is listed.
Yes thanx for the info Mamu.
xLow: It's the control pin maximum positive on the control pin to allow it to turn off IF I understand this. So zener + .... wait a minute... no, I have to go look again. I don't have my brain around this yet.
[“E” version]
ON = +2 V. to +Vin max.,
49KΩ pulldown to ground
OFF = open pin or –0.3 to +0.4 V. max.
1 mA max.
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Here's the info from the standard 6amp version I have:
Remote On/Off Control (Note 5) [Standard version]
Positive Logic ON = +1.5 V. to +Vin max. or open pin
OFF = –0.3 to +0.4 V. max. or ground pin
Current 1 mA
After reading this and trying to research Positive Logic I've royally confused myself with how the Remote on/off works.
Oh here is what the data sheet says in "Note 5":
(5) The On/Off Control is normally controlled by a switch or open collector or open drain transistor.
But it may also be driven with external logic or by applying appropriate external
voltages which are referenced to Input Common.
Can anyone explain what this means?
Remote On/Off Control (Note 5) [Standard version]
Positive Logic ON = +1.5 V. to +Vin max. or open pin
OFF = –0.3 to +0.4 V. max. or ground pin
Current 1 mA
After reading this and trying to research Positive Logic I've royally confused myself with how the Remote on/off works.
Oh here is what the data sheet says in "Note 5":
(5) The On/Off Control is normally controlled by a switch or open collector or open drain transistor.
But it may also be driven with external logic or by applying appropriate external
voltages which are referenced to Input Common.
Can anyone explain what this means?
Here's what I think it's telling us:
IF the reg is ON because there is a high + on the control pin you will have to lower it down to +0.4v or lower to turn the device OFF. You can also tie it to ground to turn it off.
IF the reg is OFF because you have the control pin tied to ground (or a very low +V) you will have to raise the control pin to at to at least +1.5v to turn it ON. Taking the control pin to open will also cause the reg to turn on.
I further assume that +0.5v thru +1.4v the device stays in it's previous state or maybe this is "results are unpredictable" land. All these voltages are to use the same ground path as +Vin and +Vout.
My zeners and a little bread-board arrive tomorrow so I can set it up to see what values work, what voltages are where and what I can do to let the magic smoke out of something ;-)
IF the reg is ON because there is a high + on the control pin you will have to lower it down to +0.4v or lower to turn the device OFF. You can also tie it to ground to turn it off.
IF the reg is OFF because you have the control pin tied to ground (or a very low +V) you will have to raise the control pin to at to at least +1.5v to turn it ON. Taking the control pin to open will also cause the reg to turn on.
I further assume that +0.5v thru +1.4v the device stays in it's previous state or maybe this is "results are unpredictable" land. All these voltages are to use the same ground path as +Vin and +Vout.
My zeners and a little bread-board arrive tomorrow so I can set it up to see what values work, what voltages are where and what I can do to let the magic smoke out of something ;-)
Okay good I guess I'm on the right track, thanks skip! Let us know what you come up with.
Is it possible to get the LED to not fire under 3v with just a larger dropping resistor? Rat Shack didn't have any zeners under 3v for the LED. I picked up a pack of 680 & 1k ohm resistors just in case that might work.
UPDATE: Never mind... I see now that u r running the LED off the triggering circuit not off the output side therefor a matching 5.6v zener will work.
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I think you mean not light under 6v, right?
Yeah, you got it figured out. You need a zener diode or a series of LEDs with a forward voltage that totals around 6v for a batt status indicator. Instead of wiring to the converter, you could wire it (with a separate switch so it's not on all the time) to the pos batt terminal and ground. Or if you have the space for it, you can also wire the LED with a shunt regulator so the LED lights when the voltage is above a preset voltage value and not light when it is below the preset voltage value. No dimming in between - the LED is either brightly lit or not at all.
Well at the time I did mean 3v because I had it breadboarded between the output pin and ground so I wanted it to not light when Vout was below 3v (meaning the zener on pin 1 is no longer fully triggering the regulator on). I now have it set up on pin 1 like you did with a 5.6v zener in the LED's path to ground. However, it's just flashing on and then real dim or out but the other zener has not quite stopped reversing so the reg is still firing (under load battery voltage, B+, is still at 6.45v. Both zeners are 5.6v and out of the same batch. I tried another one from the package but same thing. For some reason the LED one is shutting down before the pin 1 zener even after removing the LED dropping resistor.
I need to put a different set of batts in it (fully charged ones) and confirm that the LED is full bright with those in first.
I'll look at this again today but if you have any thoughts I'm all ears (or maybe eyes in this case).
Thanx, Skip
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I don't understand the reasoning for the first part you said.
But the LED will flicker/dim under load, especially when the batts voltage drops off, cuz the LED is being a bit current starved with the atty load. If you unscrew the atty and press the switch you'll notice it doesn't flicker/dim. If you have room, use a separate small tactile switch just for the LED.
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