Inverse of Mosfet

Thread Starter

Omais Ahmed

Joined Oct 4, 2015
35
Hello everyone,

I need inverse of the attached circuit...means when I turn switch on led turns off as soon as switch off led turns on. LED should be on drain side as attached circuit shows. pls help me.circuit.png
 

AnalogKid

Joined Aug 1, 2013
10,986
The silly answer is to put the switch across the LED so it shorts it out when the switch is on.

Also, note that there is no current limiting (usually a resistor) for the LED, so unless the LED has it built-in, it will fail.

To modify your circuit:
1. eliminate R3 and connect Q1 emitter directly to GND
2. connect R1 in series between Q1 base and B1 + terminal. This turns on Q1, Q2, and the LED all the time.
3. connect the switch between Q1 base and GND. This turns off Q1 when the switch is closed.

ak
 

Thread Starter

Omais Ahmed

Joined Oct 4, 2015
35
Thanks to both of you.

I'm making ATS for generator when AC line will be disconnected then 12v battery supply turns on or vise versa...I dont want to use relay...I made ac to dc 5v circuit that will be connect to the below circuit as 5v signal.

Both of you repled me I did the same that's working fine. but I need 5v switch when I apply 5 volt (ac to dc 5v) led turns off or 12v on low led turns on.

also guide me please, I'm using arduino and driving solenoid and Ignition by mosfet taking 5v from arduino and switch 12v using mosfet. Is it safe?

Thanks
 

shortbus

Joined Sep 30, 2009
10,045
thanks
I dont want to use any kind of relay.
The SSR referenced in post#5 is called a "relay" but it is solid state, meaning it uses mosfets to do the job. It doesn't have contact points and a coil. Basically does what your asking in a ready made circuit that is a sealed module.
 

Thread Starter

Omais Ahmed

Joined Oct 4, 2015
35
The SSR referenced in post#5 is called a "relay" but it is solid state, meaning it uses mosfets to do the job. It doesn't have contact points and a coil. Basically does what your asking in a ready made circuit that is a sealed module.
For ac to dc conversion or isolation?
 
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