Thanks!Hi guys! I'm trying to make a relay module to control appliances using NodeMCU but the problem I'm facing is overheating of the transistor and it stops working. Your help will be appreciated.
Image of my circuit is attached.
View attachment 268264
I have this diode but I forgot to mention it in the figure
I have replaced the transistor. Now the transistor sometimes switches on but the base current remains the same even though the transistor doesn't work i.e. almost 5 mA. Is this a transistor issue?use a multimeter and measure the Vce voltage across BC547 when it is turned on, if it is rather high like closer or > 1 v, much higher currents is passing in the transistor. An 'easy' solution is to place a resistor like 10 ohms at the emitter.
yes MCU provides 3+ voltsHello,
As said, you need a suppression diode.
What is the output voltage of the MCU?
If it is lower as the mentioned 3.3 Volts, you might need to reduce the value of the 500 Ohms resistor.
Bertus
But is it oriented correctly? The diode cathode (black band) should connect to Vcc.I have this diode
yes. I replaced the transistor but at 5mA base current ( which means the transistor is on ) it don't work properly.hi har,
The Base current will stay the same at (3.3v-0.63)/500R = 5.3mA
E
by Jake Hertz
by Jake Hertz
by Jake Hertz