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Hi,
I routinely have my Stamps automate things for me and have included
battery monitors with low battery warnings to indicate to me time to
charge.
I'm wondering if there is a device I can use which will allow the
Stamp to shut off power to itself when it's batteries get low so they
don't overdischarge. I'm thinking gate turn off thyristor or
something along those lines. Any ideas?
-Nickel
I routinely have my Stamps automate things for me and have included
battery monitors with low battery warnings to indicate to me time to
charge.
I'm wondering if there is a device I can use which will allow the
Stamp to shut off power to itself when it's batteries get low so they
don't overdischarge. I'm thinking gate turn off thyristor or
something along those lines. Any ideas?
-Nickel
Comments
What about a latching relay?
Jonathan
www.madlabs.info
Original Message
From: "nickel152" <nickel152@y...>
To: <basicstamps@yahoogroups.com>
Sent: Saturday, January 10, 2004 8:11 PM
Subject: [noparse][[/noparse]basicstamps] Auto "turn off" devices
> Hi,
>
> I routinely have my Stamps automate things for me and have included
> battery monitors with low battery warnings to indicate to me time to
> charge.
>
> I'm wondering if there is a device I can use which will allow the
> Stamp to shut off power to itself when it's batteries get low so they
> don't overdischarge. I'm thinking gate turn off thyristor or
> something along those lines. Any ideas?
>
> -Nickel
>
>
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>
>
>
>
> I'm wondering if there is a device I can use which will allow the
> Stamp to shut off power to itself when it's batteries get low so they
> don't overdischarge.
I'm using an Omron G6EK latching relay, but that was to give me enough carry
amperage to power the whole robot. If you're just powering the Stamp itself,
a reed relay will do the trick. Al Williams posted a Circuit of the Month
awhile back that had just that purpose in mind. Basically, you bypass the
relay with a normally-open momentary switch. When power is off, pressing
this switch boots the stamp. The first few instructions must activate the
relay while the momentary switch is still depressed. There's ample time of
course. But once the switch is released, the relay is what powers the Stamp,
and the Stamp has control of that relay, so it can shut itself down.
Gary
>
>I routinely have my Stamps automate things for me and have included
>battery monitors with low battery warnings to indicate to me time to
>charge.
>
>I'm wondering if there is a device I can use which will allow the
>Stamp to shut off power to itself when it's batteries get low so they
>don't overdischarge. I'm thinking gate turn off thyristor or
>something along those lines. Any ideas?
>
>-Nickel
Is SLEEP a possibility?
DO WHILE batteryLow
SLEEP 64800 ' sleep 18 hours
LOOP
reduces battery drain to ~50 microamps (given that i/o is shut down properly).
A zero power solution would use an external switch, something like this:
LP0701 p-mosfet
S D
+5 -o
;-; ;
o
Vdd
| ======== |
| |G `--/\/\--com
| | 3.3k
| |
| | 330 330
` --/\/\--o--/\/\--o--/\/\---P0
10k |
> N.O. button
|
`
com
Pressing the pushbutton brings the gate of the mosfet to ground,
turns on the mosfet, and applies 5 volts to Vdd. The Stamp starts
up, and the program brings P0 low to hold the mosfet on after the
pushbutton is released. When the Stamp wants to turn itself off, it
drives P0 high, which turns off the mosfet and releases the power on
Vdd. The 3.3k pulldown resistor defeats leakage currents. There
can't be any parasitic power coming in thru other Stamp i/o pins.
The LP0701 is a low resistance, low threshold, p-channel mosfet. A
similar scheme could turn off the power at the Vin pin, but that
would require an additional transistor.
-- regards,
Tracy Allen
electronically monitored ecosystems
mailto:tracy@e...
http://www.emesystems.com
I do need the zero power solution. I've currently implemented a relay
with a bypass button to power up the Stamp as others have suggested.
Works well. I also have a Power MOSFET I'm going to try later since I
really don't like using relays if I don't have to because of the
reliability issues. Thanks.
-Dave
--- In basicstamps@yahoogroups.com, Tracy Allen <tracy@e...> wrote:
> >Hi,
> >
> >I routinely have my Stamps automate things for me and have included
> >battery monitors with low battery warnings to indicate to me time
to
> >charge.
> >
> >I'm wondering if there is a device I can use which will allow the
> >Stamp to shut off power to itself when it's batteries get low so
they
> >don't overdischarge. I'm thinking gate turn off thyristor or
> >something along those lines. Any ideas?
> >
> >-Nickel
>
> Is SLEEP a possibility?
> DO WHILE batteryLow
> SLEEP 64800 ' sleep 18 hours
> LOOP
>
> reduces battery drain to ~50 microamps (given that i/o is shut down
properly).
>
>
> A zero power solution would use an external switch, something like
this:
>
> LP0701 p-mosfet
> S D
> +5 -o
;-; ;
o
Vdd
> | ======== |
> | |G `--/\/\--com
> | | 3.3k
> | |
> | | 330 330
> ` --/\/\--o--/\/\--o--/\/\---P0
> 10k |
> > N.O. button
> |
> `
com
>
> Pressing the pushbutton brings the gate of the mosfet to ground,
> turns on the mosfet, and applies 5 volts to Vdd. The Stamp starts
> up, and the program brings P0 low to hold the mosfet on after the
> pushbutton is released. When the Stamp wants to turn itself off,
it
> drives P0 high, which turns off the mosfet and releases the power
on
> Vdd. The 3.3k pulldown resistor defeats leakage currents. There
> can't be any parasitic power coming in thru other Stamp i/o pins.
> The LP0701 is a low resistance, low threshold, p-channel mosfet.
A
> similar scheme could turn off the power at the Vin pin, but that
> would require an additional transistor.
>
> -- regards,
> Tracy Allen
> electronically monitored ecosystems
> mailto:tracy@e...
> http://www.emesystems.com
>Hi,
>
>I routinely have my Stamps automate things for me and have included
>battery monitors with low battery warnings to indicate to me time to
>charge.
>
>I'm wondering if there is a device I can use which will allow the
>Stamp to shut off power to itself when it's batteries get low so they
>don't overdischarge. I'm thinking gate turn off thyristor or
>something along those lines. Any ideas?
>
>-Nickel
Nickel,
Here is a circuit that I have used for externally switched events
which draws less than 3 nano Amps in standby.
http://www.angelfire.com/wizard/y2kbc/STAMPS/lps.gif