Elenco 130-in-1 Electronics Playground - Manual (Page 47)

-47-
It is easy to determine what the NOR (inverted OR)
circuit does now that you have built and learned
about the NAND (inverted AND) circuit. When either
terminal A or B is connected to terminal H (119) the
display shows L. When low inputs are received by
terminals both A and B then the circuit output is high.
In the OR circuit this is the opposite. The schematic
shows the logic symbol for the NOR circuit. A + B is
the writing for the function. The OR is symbolized by
the + and the bar over the symbol signifies that the
circuit is inverted.
The current path for the LED is complete when you
connect either A or B (or both) to terminal H, turning
the NPN transistor on. The transistor and the LED go
off when you connect both A and B to L.
Notes:
EXPERIMENT #32: “NOR” TRANSISTOR CIRCUIT WITH DISPLAY
Wiring Sequence:
o 18-19-20-119
o 25-47
o 46-82-84
o 48-124
o 81-(to 119 “HIGH” or 124 “LOW”)
o 83-(to 119 “HIGH” or 124 “LOW”)
o 121-122
Schematic
-114-
Now you are going to produce a loud sound by
combining an operational amplifier with two
transistors. After you finish the wiring, set the switch
to position A to turn on the power. You hear a loud
sound from the speaker when you press the key.
A capacitor-resistor oscillator is the signal source for
this sound. The operational amplifier acts as an
inverting amplifier, and transistors Q2 and Q3 cause
the speaker to create the sound. This circuit is called
a single ended push-pull circuit (SEPP). You have
learned about push-pull circuits. Single ended
signifies that the circuit has only one output. Most
amplifiers have a second output that is connected to
the negative (–) side of the battery.
Notes:
EXPERIMENT #95: OP AMP POWER AMPLIFIER
Wiring Sequence:
o 1-29
o 2-30
o 3-90-67-47-44
o 5-94-48-119-124
o 73-81-86-87-32-113-45-131
o 33-63-43
o 35-46-70
o 76-92-36-134
o 91-88-104-40
o 75-100-111-41
o 74-114-42
o 68-80-89
o 69-93
o 79-138
o 82-84
o 83-102-103
o 85-99-101
o 112-137
o 121-135
o 122-132
Schematic