Battery quick draining in switching circuit

[shrikanthkp]

I build a switching circuit for RF transmitter.Here NPN(BC547) transistors base gets switching signal from microcontroller & collector connected 9volt 6f22 battery through small resistor Emitter grounded directly. here 9volt sugar cube relay used & relay output (N/o)given to transmitter circuit.
Here battery gets drained (9 volt to 5 volt) within 24 hours without sending any switching signal from microcontroller.The circuit just ON condition only.
I want overcome battery discharging problem.As per my expection battery should come atlest 6 months.
Please help me.
Pl.looking forward valuable replies with great thanks.

 

[betwixt]

Schematic? We can't diagnose where the current is going without one.

Brian.

 

[shrikanthkp]

Schematic? We can't diagnose where the current is going without one.

Brian.

Attached Circuit diagram Pls help me
Thank you

 

[tpetar]

I build a switching circuit for RF transmitter.Here NPN(BC547) transistors base gets switching signal from microcontroller & collector connected 9volt 6f22 battery through small resistor Emitter grounded directly. here 9volt sugar cube relay used & relay output (N/o)given to transmitter circuit.
Here battery gets drained (9 volt to 5 volt) within 24 hours without sending any switching signal from microcontroller.The circuit just ON condition only.
I want overcome battery discharging problem.As per my expection battery should come atlest 6 months.
Please help me.
Pl.looking forward valuable replies with great thanks.

9V 6F22 battery dont have good capacity in comparison with others batteries.

For example:

Energizer 9V
https://data.energizer.com/PDFs/6F22SIL_EU.pdf

Capacity : 400 mAh (to 4.8 volts)
Capacity Test: 5 mA continuous drain (21°C)


What is standby current of your circuit, did you measure?


Better post complete circuit.



Best regards,
Peter

 

[shrikanthkp]

Just go through the circuit attached in previous reply

 

[tpetar]

Where is 9V battery in circuit, on J1 ?


Best regards,
Peter

 

[shrikanthkp]

Sorry it was written 12volt instead of 9 volt. Here whole circuit driven by 9volt battery.

 

[tpetar]

Sorry it was written 12volt instead of 9 volt. Here whole circuit driven by 9volt battery.

I didnt saw modified circuit yet, but if you use 9V battery on J1 (CON2) connector, you should know that 7805 quiescent current is typically 5mA, plus 7805 voltage regulator to produce 5V on output needs at least 7,5V-8V on input, that means that you have only 1V difference from battery or very small amount of time. Additional if voltage regulator receive input voltage bellow 7,5V your circuit will receive whole amount of input voltage which can kill your parts in circuit (microcontroller).


Best regards,
Peter

 

[shrikanthkp]

Thank you valuable suggestions
Shrikanth KP

 

[tpetar]

You can try with LDO voltage regulators with small voltage difference Vi-Vo around 300-500mV-1V and with small quiescent current in uA.


Best regards,
Peter

 

[shrikanthkp]

this circuit battery drains very fast.LDO not available at our place i enquire about LDO also.But in car remote control they use small 12volt batteries.that will will not discharge years together. This circuit also same kind like remote switch.

 

[betwixt]

I'm guessing the small IC is a microcontroller, the bigger one is a data encoder and the transmitter is a small 433MHz AM type. Am I correct? you haven't given any part numbers.

The advice in previous posts is absolutely right but if my assumption about the parts is correct, I do something similar in a solar powered transmitter for remote water monitoring. My approach was to encode the data in the micro and forget the encoder IC and I also powered the transmitter directly from an I/O pin on the micro so it could be completely powered down when not in use. I did not use a relay which in itself is quite power hungry. I managed to get the power consumption down to about 10uA while idle and about 5mA when transmitting so under your battery conditions it would last for maybe a year.

Brian.