The LM35 temperature sensor provides an output of 10 mV/C for every degree Celsius over 0C. At 20C the output voltage is 20 10 = 200 mV. The circuit consumes 00...
When SI (sensor) is closed, power is applied to U2, a dual timer. After a time determined by C2, CI is ene..
A phase-controlled dimmer delays the triac turn-on to a selected point in each successive ac half cycle. Use this circuit only for incandescent lamps, heaters, soldering irons,..
A high-gain amplifier using a UA741 is used to sense relative voltage drop in a conductor, and therefore current i..
The meter reading is directlyjproportiona! to the logarithm of the input light power. The logarithmic circuit behavior arises from the nonlineardiode pnjunction current/voltage relationship..
Inserting two 1-MO resistors, R1 and R2, in the output stage of one of the circuit"s inverters limits the current needed by the oscillator tone more than a few pA. This circuit includes a CD4007 package, which has three CMOS inverters. It forms a standard three-inverter oscillator. Resistors R1 and R2, in series with separate drains on inverter pins 8 and 13, limit the oscillator"s supply current. Capacitor C1 and resistors R5 set the off time of the oscillator, C1; R6.....
A gas sensor (TGS823 from Allegro Electronics, Cornwall Bridge, CT 06754) conducts in the presence of explosive gases. U5 is a voltage-to- frequency converter that produces a frequency proportional to the sensor conductance. The output frequency ranges from 100 IIz in clean air to 8 kHz in a contaminated atmosphere. The dc voltage from the sensor also drives bar graph LED U7 and comparators U4-b and U4-c to sense present caution and danger levels. ..
Applying voltage to the circuit triggers SCR1. With SCRl on, the voltage on the anode of SCR2 rises until SCR2 triggers to commu-tate SCRl. The voltage on the gate of SCRl will swing negative at this time, and only after a positive potential of 0 volt is once again attained, will SCRl retrigger..
Although theIR region is free from radio interference, it is subject to interference from incandescent lamps, fluorescent lamps, stray reflections, and other sources. A simple way to overcome that problem is to create a carrier by chopping the IR radiation at a rate of 100 kHz. The audio then modulates the carrier by modulating the chopping rate. A receiver then detects the IR beam as a 100-kHz FM signal. ..
Have you ever wondered how many different colors can illuminate a LED? One, two or maybe three? Constructing this simple circuit, you will find it much more. The key component in this design is a dual LED. One such accessory includes two inside the 'slices' of different diode LED, that each of them produces a different color (usually green and red). For the drive requires three pins, a common cathode and two separate roots. In this way each of the two integrated diodes can.....
The 5AH will trigger when the voltage across the two 0 juF capacitors reaches the breakdown voltage of the lamp. Control can be obtained full off to 95% of the half wave RMS output voltage..
The sensor is based on the selective absorption of hydrocarbons by an n-type metal-oxide surface. The heater in the device serves to burn off the hydrocarbons once smoke or gas is no longer present in the immediate area; hence, the device is reuseable. When initially turned on, a 15 minute warm-up period is required to reach equilibrium (V, = 0.6 V) in a hydrocarbon-free environment. When gas or smoke is introduced near the sensor, VA will quickly rise (rate and final.....
Ql senses IR from heat sources, causes U1 to switch, activates optocopuler Ul, and triggers TR1. This contro..
The flash rate is determined by CI and R4. ..
Using a capacitor sensor to detect a water level is a simple method of sensing. This circuit uses C5, which..
The two lamp-dimmer circuits differ in that (a) employs a single-time-constant trigger network and (b) uses a double-time-constant trigger circuit that reduces hysteresis effects and thereby extends the effective range of the light-control potentiometer. (Hysteresisre-fers to a difference in the control potentiometer setting at which the lamp turns on and the setting at which the light is extinguished) The additional capacitor C2 in (b) reduces hysteresis by charging to a.....
If a NiCad battery is discharged to a point at which the lowest capacity cell becomes fully discharged and reverses polarity, that cell will usually short internally and become unusable. To prevent this type of damage, this circuit detects a one-cell drop of 1.25 V and turns the load off before cell reversal can occur. Low-current zener or other voltage sensor Dl and resistors Rl and R2 establish a reference level for transistor Ql. ..
This is a cross-sectional diagram of a flex switch. They can be used as pushbutton or even position sensors. This schematic diagram shows an oscillator, which is used as an alarm sounder,..
This astable multivibrator uses incandescent lamps in place of collector load resistors. ..
ICl is a 555 timer running at about 16 kHz. This IC drives Ql, a TIP146, which produces a 12-V square wave across Tl pri..
Operational Amplifiers
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