Which power supply is best ...

[yusuf]

I have cmos circuit and I want a 12v power supply ?

I have 12v transformer and a 12v nokia mobile charger(Nokia mobile charger output is 6v so I have attached two 6v nokia mobile charger to gain 12v)

I Have this circuit which drives relay and the relay drives pump..

SO which power supply is good...

 

[Reloadron]

Yusuf, you should know by now that the best power supply would be the power supply that can easily meet the demands of the pump motor as well as your circuit. That includes any surge current the pump motor may draw on start. Additionally when a motor starts and draws an inrush current it can cause the bus voltage to drop from the PSU, that sudden drop can wreak havoc with your CMOS. In most cases it is unwise to run a pump motor and CMOS circuits off the same power source. Since you do not post any current specifications there is no way to answer your question. However, I will tell you that I would never consider using a pair of 6 volt Nokia (or any other) mobile charger units in series as a power supply or source for a project involving a pump motor and CMOS circuits. Take it for what it is worth.

Just My Take
Ron

 

[MrDEB]

Two mobile chargers in series!!
I can smell smoke, That magic smoke from electronics

 

[yusuf]

Thanks Reloadron ! for your reply .....
Ok so we need separate power supply for CMOS circuit and Relay....

I have 18v-0-18v transformer...
So can I use this transformer and 8v & 12v regulator ... to give 8v to CMOS Circuit and 12v to Relay circuit...

Thanks...

 

[Reloadron]

I believe I mentioned the supply needs to be able to deliver the current required by the pump motor and elaborated on that a little? Yusuf, you have not stated what the pump requires for run and start current? You need to consider all of the variables.

Ron

 

[yusuf]

I dont know current but my motor is 500 watts...

 

[Reloadron]

What is this pump? How have you been running it? A motor that runs on 12 volts and consumes 500 watts? That would be 500 / 12 = 41.66 amps. This makes no sense to me? Are you just powering the circuit and relay coil? That may explain it as my take was you are driving the pump with power for the pump. That is why I spent time on the motor.

Ron

 

[Brevor]

What is this pump? How have you been running it? A motor that runs on 12 volts and consumes 500 watts? That would be 500 / 12 = 41.66 amps. This makes no sense to me? Are you just powering the circuit and relay coil? That may explain it as my take was you are driving the pump with power for the pump. That is why I spent time on the motor.

Ron

Ron, I think the 12 volt relay switches the pump motor, I believe he just wants to power the CMOS circuit and the relay.

 

[Brevor]

I have 18v-0-18v transformer...
So can I use this transformer and 8v & 12v regulator ... to give 8v to CMOS Circuit and 12v to Relay circuit...

Why not use the 12 volt regulator to power both the CMOS and the relay ?
No need for the 8 volt regulator.

 

[Reloadron]

Ron, I think the 12 volt relay switches the pump motor, I believe he just wants to power the CMOS circuit and the relay.

That's the drift I am beginning to get. I believe I had it wrong from the staer.

Ron

 

[yusuf]

thanks for reply friends...

I have 240v and 500watt motor pump.....
means it will draw : 2.08 Ampere
And I have 12v and 10 ampere relay which needs 100ma to run on 12v.

Why not use the 12 volt regulator to power both the CMOS and the relay ?
No need for the 8 volt regulator.

i am giving separate power supply to cmos and relay to protect from very high rushing current..
i have cmos timer circuit so the high current rush at the relay will disturb the cmos timer circuit and the timer also can reset.....

so , i want separate supply to cmos and relay driver circuit...
I have 18v0-0v-18v center taped transformer and 7812 , 7808 voltage regulator for 8 , 12v regulation....

in both voltage (8 and 12v) i want 200ma current...

thanks in advance...