I thought, for such a simple circuit a verbal description were enough .
Connecting base to ground did not help.
So I built an equivalent circuit without the PICO on a breadboard, just substituted an LED-Diode plus a series resistor for the buzzer.
I used another transistor of the same type.
I got the same bad result, LED on with base grounded and Vss 22 Volt.
Then I changed the transistio to a BCY59A, NPN, 45V, 0,2A, 0,345W, TO-18, and everything works as expected.
Obviously, the the previously used BC547C, NPN, 45V, 0,1A, 0,5W, TO-92 cannot handle 22 V Collector to Emitter voltage.
I wonder, what the 45V in the description stands for?
Connecting base to ground did not help.
So I built an equivalent circuit without the PICO on a breadboard, just substituted an LED-Diode plus a series resistor for the buzzer.
I used another transistor of the same type.
I got the same bad result, LED on with base grounded and Vss 22 Volt.
Then I changed the transistio to a BCY59A, NPN, 45V, 0,2A, 0,345W, TO-18, and everything works as expected.
Obviously, the the previously used BC547C, NPN, 45V, 0,1A, 0,5W, TO-92 cannot handle 22 V Collector to Emitter voltage.
I wonder, what the 45V in the description stands for?
Statistics: Posted by ulrichmuc — Thu May 01, 2025 5:47 pm