What will happen when two switches are ON?

That's not a normal state. If you do that then the two sources will be shorted together.

 

hi...
if the sources is 12vdc from solar panel and 12vdc from recharger, is there a big changes on mr. crutschow circuit

is there change in resistors value or transistors types?????
thanks....

If both sources are 12vdc then you can change the circuit slightly:

Remove the 10kΩ resistor on the top circuit and replace with a short.

Connect the bottom 10kΩ resistor to the bottom supply instead of the top supply.

The top supply must be the always on charger.

Edit: The above will work only if you bottom supply is no more than about 1/2 volt greater than the top supply. If it is then you will need to make the top switch with dual P-MOSFETS, the same as the bottom switch.

 

That's not a normal state. If you do that then the two sources will be shorted together.

I just thought that if necessary it can be add two transistors and resistors to aviod that kind of status.

 

mr. crutschow...
is this circuit modified right as you explain in ur last reply.

question:
can replace the two switches with relay to let the circuit work automatically,(The above will work only if you bottom supply is no more than about 1/2 volt greater than the top supply) I want this done automatically??????
thanks....

 

The top left MOSFET needs to have the source and drain interchanged.

Also you can make both gate-source resistors 10K ohms.

Don't understand your question about 1/2 volt and relay?

 

The top left MOSFET needs to have the source and drain interchanged.

Also you can make both gate-source resistors 10K ohms.

is this right

Don't understand your question about 1/2 volt and relay?

can replace the switch in the circuit with a relay, if it possible can u draw the circuit please?
thanks crutschow....

 

Which switch?

 

Which switch?

switch marked in the circle

 

If you are going to use a relay, why not just use a SPDT relay to switch the voltages and eliminate the MOSFETs? Connect the two voltages to the two fixed relay contacts and the relay wiper contact to the load.

 

The four MOSFETs already replaced the Relay's job, why you want to use Relay to replace the switch?
if you want to use them as contrl iinput, then maybe you can adding transistors to be the control pins.

 

Perhaps I should have stated that the switches shown are just for simulations purposes. You can, of course, remove the switches and control the transistors with signals from your microprocessor, which was your original intention, I believe.

 

Hello All,

I would like to switch between two voltage sources, namely +24v and +5v. I have been trying to do with MOSFET. IRF530 and IRF5305, but i always fail. I have been using the following circuit that i found. http://www.electronics-tutorials.ws/transistor/tran_7.html . I will be doing the switching using MICROCONTROLLER.Please advise on this.

Or, Is there any other better way to do this ?

Thanks

Hello ,

see my schema , use a P MOS and 2 npn transistor ,

https://github.com/esaid/switch-power-source-

 

Welcome to the forum, esaid.
I see you've also joined many of the first timers as a member the AAC necromancy club.
This thread is over 3 years old so I doubt the OP still needs a solution.