i need a circuit for current controlled current source , actually i have 2 operate relays through the pic microcontroller bt its current is to small as compared to the required current drawn by rellay , so i thought to make a curnt controlled current source that cud help, please tell me if this culd be done by some other way to, i,l b oblidged
current controlled current source
- Thread starter talhaali
- Start date
A VERY common way to power relays or other devices that require more current than a micros outputs can supply is to drive a transistor with the micro pin and use that to switch on a secondary power source like shown in the attached pdf
http://www.arduino.cc/playground/uploads/Main/relays.pdf
http://www.arduino.cc/playground/uploads/Main/relays.pdf
A switched voltage source may work better. Relays typically have a defined coil resistance so all you need do is give them their rated voltage and they control their own current. So all you would need is a transistor and a catch diode. Lots of references for those around.
Your micro drives the transistor base thru a resistor, and the transistor switches the relay. This way the relay can run off a different voltage (higher or lower) then the micro does.
Your micro drives the transistor base thru a resistor, and the transistor switches the relay. This way the relay can run off a different voltage (higher or lower) then the micro does.
