I have been trying to use Transistor in place of Relay (as relay causes noise) but i m afraid...every transistor has PN junction voltage drop. Please can you gimme idea/design how to use transistor as pure switch means no voltage loss.....
Use a MOSFET. It has a drain-to-source resistance when conducting (Rdson) and at low voltages, the voltage drop should be very small. You can get MOSFETs with very very small Rdson, which will result in near-zero voltage drop. N-channel MOSFETs tend to have lower Rdson than P-channel MOSFETs for similarly rated devices.
go to either digikey or mouser website, search MOSFET, then device parameters you would look for say Vgs breakdown ~10-12V, choose RDSon low value,
choose continuous drain current. Prices vary, generally, lower RDSon => more $
you need to check with the datasheet, how "on" it is at 5V - aka logic level - there is usually a graph Vgs and RDSon.
You might then find the same part numbers at your preferred supplier.
This is the MOSFET Driver circuit i have designed. Please comment is is true ? Thanks. My PIR output is 3.3volt. When i connect directly with IRF540N it works but my Display (load) is little dim. Means directly using 3.3v its not fully on.
sorry the transistor symbols are wrong...else i think everything is fine... please do comment...will it work.. i want to use IRF540 as Pure switch as its RDson is very low..
Here's an untangled drawing. I changed R1 and R2 to (IMHO) more sensible values, and added another three resistors which weren't in the original schematic but seemed like a good idea to me. I'm not sure if the gate stopper (R5) is really needed though.
Here's an untangled drawing. I changed R1 and R2 to (IMHO) more sensible values, and added another three resistors which weren't in the original schematic but seemed like a good idea to me. I'm not sure if the gate stopper (R5) is really needed though.
I donno why it is working but output from PIR is 3.3Volt and IRF540N is switched on easily. If i give 3.3Volt and is turned on, means there would be less voltage/current flowing ? full current will flow only when its 10Volt ?