Need a 6v Relay switching circuit with PNP transistor with 5v dc source

Hello Friends,
I would like to switch a a relay when no signal coming, for that i used a PNP transistor switching circuit. In this circuit i am using same same supply voltage to the coil of relay as well as the base of transistor. Unfortunately there is some problems in the circuit. Any one can modify my circuit of suggest a new circuit for switching the relay. I am using only a DC 5 voltage supply in this circuit, the relay also can switch in 5v. Please help me.
I attached 2 circuits i tested

switching ckt.PNG

switching ckt.PNG

Left hand cct. is needed.

Add a 1k resistor from left side of R1 to GND.

Switch closed, relay dropped.

Switch open relay picked.


“ no signal coming”

What signal ?

Hello larryd,

I followed your suggestion and it was perfect, the circuit is working. But now i am facing another issue. Actually i am doing a water tank automatic switch to switch off the motor when water tank is full. but when the water pump is on, water level is moving up and reaching near the sensor, then the sensor output is switching ON OFF for some seconds because of the waves in water, then the water pump also toggling ON OFF.

So i used a timer circuit. What is my intention is, after the first low signal from the sensor the relay should be triggered by the timer circuit for some seconds( till the end of sensor output is toggling by the water wave). After the sensor output is stable the relay switching done by PNP switching circuit.

For this purpose i used a circuit. But this circuit is working only once. After the first negative signal the timer activated and relay triggered by timer circuit but after some seconds timer will off but the relay switching is not shift back to PNP transistor.The current flow will be like this in the figure i attached.I hope you will under stand what i explained. I request you to help me to modify my circuit as per my requirement. Thank you

When you need to turn the pump off (tank is full), does your switch (SW1) CLOSE or OPEN ?


EDIT:

Does this describe the situation when the tank is empty ?
(contact "A" would be closed and the water pump would be running)

ec_works:
Hello larryd,

I followed your suggestion and it was perfect, the circuit is working. But now i am facing another issue. Actually i am doing a water tank automatic switch to switch off the motor when water tank is full. but when the water pump is on, water level is moving up and reaching near the sensor, then the sensor output is switching ON OFF for some seconds because of the waves in water, then the water pump also toggling ON OFF.

So i used a timer circuit. What is my intention is, after the first low signal from the sensor the relay should be triggered by the timer circuit for some seconds( till the end of sensor output is toggling by the water wave). After the sensor output is stable the relay switching done by PNP switching circuit.

For this purpose i used a circuit. But this circuit is working only once. After the first negative signal the timer activated and relay triggered by timer circuit but after some seconds timer will off but the relay switching is not shift back to PNP transistor.The current flow will be like this in the figure i attached.I hope you will under stand what i explained. I request you to help me to modify my circuit as per my requirement. Thank you

I had exactly the same problem with my irrigation water storage system. Domestic well water into storage tanks controlled by top and bottom float switches. You have never identified your sensor for water level.

On my system, as soon as the top float was triggered, I turn off the solenoid valve and set a boolean that stops any further level tests until the bottom float switch is triggered, then the Boolean is reset.

You can do the same with whatever sensor you have.

Paul

ec_works:
but when the water pump is on, water level is moving up and reaching near the sensor, then the sensor output is switching ON OFF for some seconds because of the waves in water, then the water pump also toggling ON OFF.

This is why you always have two level sensors, and each only enables or disables the pump. If you have
one sensor both enabling and disabling you’ll get rapid switching artifacts like this, basically you need
hysteresis in the position sensing, which means two binary level sensors, or a linear level sensor with
two threshold values.