low power voltage monitor

Archiver

Hi

We built a battery voltage monitor in the standard way just using a
741 op amp. (we want to monitor for a low voltage condition on a
12volt battery) We ran the output into a BS2SX. Everything works
good, but it draws a lot of power. (>50ma) Is there a bettery, more
conservative way to do this?

Jody

Archiver

The simplest way would be to connect a Zener diode to a stamp pin, and maybe
a small load resistor to ground.
in selecting the zener remember to allow for ~1.4vdc to turn the stamp pin
high. For example a 1N4741a with a 100K load to Ground will read high near
12.25 volts and draw less than a milliamp.

---

From: "moparjody" <jody.gallant@

> Hi
>
> We built a battery voltage monitor in the standard way just using a
> 741 op amp. (we want to monitor for a low voltage condition on a
> 12volt battery) We ran the output into a BS2SX. Everything works
> good, but it draws a lot of power. (>50ma) Is there a bettery, more
> conservative way to do this?
>
> Jody

Archiver

Go to http://www.bobblick.com/bob/stamp/555a_d/index.html

It shows how to set up a 555 timer as a kind of ADC to convert a
voltage level into a pulse that varies with the voltage level. I
have incorporated this circuit into my robot power monitor and works
great.

Hal


--- In basicstamps@y..., "moparjody" <jody.gallant@s...> wrote:
> Hi
>
> We built a battery voltage monitor in the standard way just using a
> 741 op amp. (we want to monitor for a low voltage condition on a
> 12volt battery) We ran the output into a BS2SX. Everything works
> good, but it draws a lot of power. (>50ma) Is there a bettery,
more
> conservative way to do this?
>
> Jody