The following PWM circuit only need two inverter gates, therefore 3 independent PWM circuit using only one IC can be made. This is because there are at least 6 inverter gates in one IC package.
To stabilize their output to a determined value, any input pin of any unused gates should be connected to ground or to VCC. This would prevent them of swinging to high or to low if the input pins are floating and exposed to noise. This circuit is applicable to control heaters, DC motors, or incandescent lamp.
The following illustration is the circuit schematics of single transistor microphone pre-amplifier for both dynamic and condenser type mic. The two kinds of microphone have different characteristics. Dynamic microphone does not need biasing current because the transducer generate the electrical signal. On the other hand, the condenser microphone needs a bias current to compensate the leakage in the microphone and also because of the pre-amplifier loading discharging the condenser mic’s electrical charges. Here is the circuit diagram of the microphone pre-amp which provides input terminal for both types using only a single transistor as the active components.
9V battery is used on this circuit, however, 6-15V battery can also be used without modification. The input for dynamic microphone is decoupled with C3, and thus DC-isolated from any DC voltage coming from R2 and R1. When only the condenser mic that you need, then C3 can be omitted. When the dynamic mic is needed, R1,C1, and C2 components can be omitted as well.
The caps is wired back-to-back at C1 and C2. This configuration prevents the leakage current in the reserved direction of the capacitor polarity. This back-to-back capacitors emulate a non-polar capacitor with two low cost electrolityc capacitors. Any small signal NPN transistor with high gain (hfe > 150) should be compatible to replace Q1, for examples: 2N3904, FCS9014, C828, or C945.
The B6304s engine of Volvo 960 was the first generation of modular inline 6-engines. The engine is a 6-cylinder, liquid-cooled, gasoline, in-line engine using aluminium alloy cylinder block with cast-iron cylinder liners which is casted directly into block and aluminum alloy cylinder head with double overhead camshafts, separate outlet and inlet channels.
The following picture illustrates the engine compartment of Volvo 960 1994. The engine produces output: (SAE J 1349) 201 hp at 6000 rpm; max. torque (SAE J 1349) at rpm 197 ft. lbs. (267 Nm) at 4300 rpm; Bore 3.27? (83 mm); Stroke 3.54? (90 mm); Displacement 2.92 liters; and Compression ratio 10.7:1. Here is the picture as well as the legend :
1. Expansion tank, coolant
2. Engine oil filler cap
3. Engine oil dip-stick
4. Brake fluid reservoir
5. Data plate
6. Battery
7. Radiator
8. Power steering fluid reservoir
9. Air cleaner
10. Washer fluid reservoir
