Hi guys i need help with my monostable circuit! I am using monostable circuit to switch off my motor after a specific period of time but the motor wont stay on when i press the button switch... When i remove the relay and motor and replace it with led, the led stays on for a while before switching off. I am very sure that there is no problem with my monostable circuit but i don't get why my motor wont stay on! Can it be the relay or my circuit itself? Please help.

 

Please post a schematic.

 

Hi guys i need help with my monostable circuit! I am using monostable circuit to switch off my motor after a specific period of time but the motor wont stay on when i press the button switch... When i remove the relay and motor and replace it with led, the led stays on for a while before switching off. I am very sure that there is no problem with my monostable circuit but i don't get why my motor wont stay on! Can it be the relay or my circuit itself? Please help.

The battery may be very low (nearly used up) and when the motor is drawing current, could bring the old battery's voltage so low that the 555 timer resets. Try using a new battery or add a second battery in parallel with your existing battery.

 

Please post a schematic.

This is the schematic diagram for the circuit. From pin 3, i connected a resistor to a relay. I am not sure whether i have wired it correctly, but the monostable circuit works without the motor and relay. My teacher helped me with the wiring but i am not sure why it doesnt work.

this is the relay i am using.

 

Can i just connect the motor to pin 3 without a relay? Would it work?

 

Can i just connect the motor to pin 3 without a relay? Would it work?

It depends on the motor. Does it say how many milliamps it draws at 9 volts? The 555 can output up to 200 mA.

 

The battery may be very low (nearly used up) and when the motor is drawing current, could bring the old battery's voltage so low that the 555 timer resets. Try using a new battery or add a second battery in parallel with your existing battery.

I am already using a new battery, maybe its just my relay?

 

I am already using a new battery, maybe its just my relay?

Which transistor are you using? Change the 10k that connects 555 pin 3 to base of transistor to 1k.

 

It depends on the motor. Does it say how many milliamps it draws at 9 volts? The 555 can output up to 200 mA.

nope it doesnt say anything

 

Which transistor are you using? Change the 10k that connects 555 pin 3 to base of transistor to 1k.

the transistor i am using is actually provided by my teacher

 

It depends on the motor. Does it say how many milliamps it draws at 9 volts? The 555 can output up to 200 mA.

I tried connecting the motor without the relay to pin 3. It worked one time and it doesnt work anymore.

 

I tried connecting the motor without the relay to pin 3. It worked one time and it doesnt work anymore.

Evidence that the motor draws more than 200 mA. Your 555 may be dead. Does the LED light if you connect it again?

Which country are you from?

 

Evidence that the motor draws more than 200 mA. Your 555 may be dead. Does the LED light if you connect it again?

Which country are you from?

My 555 still works. The led light still turns on.
I am Singapore.

 

On the breadboard, there are row numbers. In row 23 on the right side of your relay there is a purple wire. It currently connects the relay coil to 9V (red) rail. Move the wire so it connects the relay coil (right side of relay) to 0v (ground).

Then, remove the resistor that connects 555 pin 3 to transistor, and Remove transistor.

Use a bare wire to connect pin 3 directly to the relay coil (on left side of relay).

Try your button again to see if motor spins.

 

On the breadboard, there are row numbers. In row 23 on the right side of your relay there is a purple wire. It currently connects the relay coil to 9V (red) rail. Move the wire so it connects the relay coil (right side of relay) to 0v (ground).

Then, remove the resistor that connects 555 pin 3 to transistor, and Remove transistor.

Use a bare wire to connect pin 3 directly to the relay coil (on left side of relay).

Try your button again to see if motor spins.

The motor still wont stay on. Can it be my relay? Maybe it is not working?
This is my connection now

 

The motor still wont stay on. Can it be my relay? Maybe it is not working?
This is my connection now]

That is exactly what I meant. Good

but now carefully lif the left side of your relay off your breadboard and look under it to make sure your wires align with the pins of the relay. The photo makes things look misaligned sometimes. Just double check the alignment.

 

That is exactly what I meant. Good

but now carefully lif the left side of your relay off your breadboard and look under it to make sure your wires align with the pins of the relay. The photo makes things look misaligned sometimes. Just double check the alignment.

it is aligned properly, but motor wont stay on. Should i change my relay?

 

The motor still wont stay on

What is the value of C1?

 

Try using an ohmmeter to verify the coil connections on the relay. The breadboard looks like the coil and contacts are swapped.

 

What is the value of C1?

value of c1 is 470uf.