Battery Monitor Circuit
Zener Diodes & Quad Differential Comparator LM 339 #BasicTronics 00
Hello Hobbyists, Welcome!
This is a Battery Monitor Circuit:
This simple low voltage tester circuit can be used to monitor battery and other voltage sources of current for problems by LED display and alarm sound.
This circuit is used to check the voltage of a 9-volt battery.
We use a LM339.
LM339 is a comparator IC with four inbuilt comparators.
A comparator is a simple circuit that moves signals between the analog and digital worlds.
It compares two input voltage levels and gives digital output to indicate the larger one.
Note that we are setting the reference voltage at the inverting terminal.
Just when the voltage set by the Zener diode is greater than the battery then the LED lights and the alarm beep.
The battery current will flow through resistor R1 to the input pin 7 (non-inverting) of the IC.
The battery discharges are simulated with a potentiometer 5k (or 10k).
We set the trigger level by Zener diode of 6 volts IN5233 (other voltages may be used, 3 volts for example, IN5225).
You can use Zener diodes in a range from 2.4 to 200 volts.
See SCHEMATIC :
Once established limits, higher 9 volts and lower v 6 volts, monitor the battery until its voltage drops below 6v the LED lights and trigger the alarm.
If we choose to control 3 volts, from the time that the battery gets below 3 volts the monitor triggers the alarm, warning us of low load.
As always questions and comments are most welcome, and thanks for watching.
Have fun! Thanks!
Notes:
- A zener diode is always operated in its reverse-biased condition;
- A voltage regulator circuit can be designed using a zener diode to maintain a constant DC output voltage across the load despite variations in the input voltage or changes in the load current; See figures a & b:
. The zener voltage regulator consists of a current limiting resistor Rs connected in series with the input voltage Vs with the zener diode connected in parallel with the load RL in this reverse-biased condition; check below:
. The stabilized output voltage is always selected to be the same as the breakdown voltage Vz of the diode;
. Normal diodes will also break down with a reverse voltage but the voltage and sharpness of the knee are not as well defined as for a Zener diode.
. Also, normal diodes are not designed to operate in the breakdown region, but Zener diodes can reliably operate in this region;
. Zener diodes Allow current to flow from its anode to its cathode like a normal semiconductor diode, but it also permit current to flow in the reverse direction when its “Zener voltage” is reached;
. Zener diodes have a highly doped p-n junction;
. The Zener Diode is used in its reverse bias or reverse breakdown mode;
. The ability to control itself can be used to great effect to regulate or stabilize a voltage source against supply or load variations;
. There are differences between Zener and avalanche breakdown. The Zener effect predominates on diodes whose breakdown voltage is below 6 V. On regular diodes, the breakdown zone is approximately 70 V or more negative.
The functions:
Zener Diode Clipping Circuits — Waveform clipper
Two Zener diodes facing each other in series will act to clip both halves of an input signal. Waveform clippers can be used to not only reshape a signal,
but also to prevent voltage spikes from affecting circuits that are connected to the power supply.
This type of clipper configuration is fairly common for protecting an electronic circuit from overvoltage. The two zener’s are generally
placed across the power supply input terminals and during normal operation, one of the zener diodes is “OFF” and the diodes have little or no effect. However, if the input voltage waveform exceeds its limit, then the Zener’s turn “ON” and clip the input to protect the circuit.
Zener Diode as Voltage shifter
A Zener diode can be applied to a circuit with a resistor to act as a voltage shifter.
This circuit lowers the output voltage by a quantity that is equal to the Zener diode’s breakdown voltage.
The Zener Diode Regulator — Voltage regulator
A Zener diode can be applied in a voltage regulator circuit to regulate the voltage applied to a load, such as in a linear regulator.
It can be used to produce a stabilized voltage output with low ripple under varying load current conditions. Bypassing a small current through
the diode from a voltage source, via a suitable current limiting resistor (RS), the zener diode will conduct sufficient current to maintain a voltage drop
of Vout.
Square Wave Signal — zener diode square wave signal
The back-to-back connected zener diodes can be used as an AC regulator producing what is jokingly called a “poor man’s square wave generator”.
Using this arrangement we can clip the waveform between a positive value of +8.2V and a negative value of -8.2V for a 7.5V zener diode.
References:
Datasheet: bhttp://pdf.datasheetcatalog.com/datasheet/central/1N5239B.pdf
Proteus-File: https://www.dropbox.com/s/9re5nzz44icuvvg/LM339_Batery_Monitor_Circuit.pdsprj?dl=0
Schema: https://www.dropbox.com/s/jt93gwfhk9287v8/lm339_batery_monitor_circuit_h.pdf?dl=0
Web-Page: http://jungletronics.blogspot.com.br/2014/09/top-27-hobbyists-chips.html
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