elsey.jack
New Member
Hello everyone,
What I thought was going to be an easy project is proving to be more of a learning experience than I anticipated.
Intended operation:
- PIC microcontroller feeds a +5 V signal to a transistor.
- The transistor allows current through, putting ~ +5.5V across the relay coil.
- The relay opens.
Actual operation:
- The circuit continually draws current (approx 25 mA) from +9 V battery even without a +5.0 V signal from microcontroller.
- Only a few volts are put across the relay coils when the transistor receives the +5.0 V signal. Most of the voltage (approx +7 V) is across the transistor!
The relay trips perfectly fine when I short out the collector and emitter leads of the transistor.
The transistor works perfectly fine when a +5 V source, LED, and resistor are connected to the collector lead instead of the relay.
Am I doing something dumb here?
View attachment 61372
What I thought was going to be an easy project is proving to be more of a learning experience than I anticipated.
Intended operation:
- PIC microcontroller feeds a +5 V signal to a transistor.
- The transistor allows current through, putting ~ +5.5V across the relay coil.
- The relay opens.
Actual operation:
- The circuit continually draws current (approx 25 mA) from +9 V battery even without a +5.0 V signal from microcontroller.
- Only a few volts are put across the relay coils when the transistor receives the +5.0 V signal. Most of the voltage (approx +7 V) is across the transistor!
The relay trips perfectly fine when I short out the collector and emitter leads of the transistor.
The transistor works perfectly fine when a +5 V source, LED, and resistor are connected to the collector lead instead of the relay.
Am I doing something dumb here?
View attachment 61372