Showing posts with label 741. Show all posts
Showing posts with label 741. Show all posts
Wednesday, September 10, 2014
Simple Thermal Fan Controller By IC 741
The controller uses one or more ordinary silicon diodes as a sensor, and uses a cheap opamp as the amplifier. I designed this schema to use 12V computer fans, as these are now very easy to get cheaply. These fans typically draw about 200mA when running, so a small power transistor will be fine as the switch. I used a BD140 (1A, 6.5W), but almost anything you have to hand will work just as well.
Thermal Fan Controller By IC 741 Circuit diagram:
Thermal Fan Controller Circuit Diagram
Source: ESP
Sunday, September 7, 2014
12W Amplifier Circuit Using 741 Op Amp Wiring diagram Schematic
A 12 watt audio amplifier operating on a dual symmetrical supply of ± 12 volts. The 741 provides the required gain while the speaker drive is provided by the complementary Darlingtons T1, T2 and T3, T4.The input signals for the darlingtons are derived from the supply current of the 741. Since R6 is connected to the ground, the positive or negative signal currents also pass through R4 or R5. The voltage drop across these resistors serves as the input signal to the transistor pairs. An overall dc negative feedback from the common collector junction of T2 and T4 stabilises the dc conditions of the schema and keeps the junction point at zero volts. Hence, no coupling capacitor is required for the speaker.
12W Amplifier Circuit Using 741 Op Amp Circuit Diagram
| PARTS LIST | |
| R1 | 10KΩ |
| R2 | 4.7KΩ |
| R3 | 270KΩ |
| R4 | 1KΩ |
| R5 | 1KΩ |
| R6 | 47Ω 1W |
| C1 | 50 Pf |
| C2 | 0.01 µF |
| T1 | BC178 |
| T2 | 2N6107 |
| T3 | AC108 |
| T4 | 2N5294 |
| IC | LM741 |
| LS1 | 50W 4Ω |
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