Click para ampliarThree Way Touch Lamp
A three-way switch to control a lamp (off-dim-bright, etc.) uses an NE555 timer to generate a one-second pulse, triggered by ambient ac fields that are picked up by the human body. C1 and D1 form an input network. U2 is a decode counter/divider and drives one of 10 outputs (three are used). The logic outputs drive various resistors in series with the LED in the optocoupler. The optocoupler controls a triac that is in series with a load (lamp, etc.).
By reconfiguring the outputs of U2, more than three brightness levels can be obtained, up to 10. An 1N914 and resistor will be required for each output.
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By reconfiguring the outputs of U2, more than three brightness levels can be obtained, up to 10. An 1N914 and resistor will be required for each output.
Click para ampliarThree Power Level Triac Controller
Three power levels are supplied by the two logic inputs of this enhanced circuit. R5, D4, D5, and
C2 form a power supply for the logic IC. They can be omitted if another source of low voltage is available.
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C2 form a power supply for the logic IC. They can be omitted if another source of low voltage is available.
Click para ampliarSensitive Triac Controller
The single transistor connected between the capacitor and the common side of the ac line allows a logic-level signal to control this triac power circuit. Resistor R2 prevents false triggering of the triac by the trickle current through the diac.
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Click para ampliarLight Modulator
The light seem to dance in time with the music. Line-voltage lamps of about 40 to 100 W do nicely. The current for the lamp is from an SCR. When low-level audio is present across T1, SCR1 is not triggered into conduction. A louder signal, however, triggers the SCR so that the lamp lights and follows the sounds.
Since SCR1 is operated by an alternating current, the rectifier moves out of the avalanche condition when the gate current is low. Potentiometer R3 lets you adjust the power reaching transformer T1, so that with normal operating volume, SCR1 triggers again and again, except during quiet passages.
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Since SCR1 is operated by an alternating current, the rectifier moves out of the avalanche condition when the gate current is low. Potentiometer R3 lets you adjust the power reaching transformer T1, so that with normal operating volume, SCR1 triggers again and again, except during quiet passages.
Click para ampliarLight Controller
LED Brightness Control
The brightness of LED display is varied by using a photocell in place of one timing resistor in a 555 timer, and bypassing the other timing resistor to boost the timer's maximum duty cycle. The result is a brighter display in sunlight and a fainter one in the dark.
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Click para ampliarDC Lamp Dimmer
A low power, low cost dc lamp dimmer for a two-wire portable "flashlight" can be realized with little or no heatsinking. In addition, a single potentiometer, R3 adjusts lamp brightness. Battery power is stored in C1 for U1, which is a free-running multivibrator whose frequency is determined by R1, R2, R3, R4, and C2. U1 drives the gate of Q1, turning it and the lamp ON and OFF at a rate proportional to the multivibrator duty cycle.
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Click para ampliarAutomatic Light Controller For Carport
A 555 timer IC, operating in the one-shot mode, is triggered by light striking photoresistors. These normally have a resistance of several megohms but, in the presence of light, that resistance drops to several hundred ohms, permitting current from the six-volt source to flow in the circuit. The R-C combination shown gives an on-time of about two minutes. Photoresistors PC3 and PC4 are mounted at headlight-height. When headlights illuminate the photoresistor, the timer starts. That actuates a relay, RY1, and the lights are turned on. The lights are automatically turned off when the timer's two minutes are up.
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Click para ampliar120 AC Shimmering Light
You can turn any ordinary household bulb into one that shimmers or blinks. This circuit works on any incandescent light up to 200 W, and runs on standard 120 Vac. The circuit uses an SCR to cause an ordinary lamp to shimmer. Note that one side of the lamp is connected directly to 120 Vac, and the other side of the lamp goes to the cathode of the SCR. As ac voltage is brought into the circuit through the line cord, it is full-wave rectified by diodes D1 and D2. That changes the ac to dc, and a portion of that dc voltage is applied to capacitor C1 through R2. Diode D3 blocks the (+) dc voltage so that only the voltage from the path of R1 and D3 is clear.
That forms an oscillator, which has a frequency determined by the setting of potentiometer P1 (because the other components have fixed values). Remember to use EXTREME CAUTION when using a device that connects to the ac line. NEVER use it outside or near water and always mount the entire kit inside a wooden or plastic (insulated) box to prevent any contact with the ac voltage.
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That forms an oscillator, which has a frequency determined by the setting of potentiometer P1 (because the other components have fixed values). Remember to use EXTREME CAUTION when using a device that connects to the ac line. NEVER use it outside or near water and always mount the entire kit inside a wooden or plastic (insulated) box to prevent any contact with the ac voltage.
Click para ampliarTriple Op Amp Instrumentation Amplifier
VOUT = VIN (1+ (R1+R2)/R3) (R6/R4)
GAIN = 100
GAIN LIN = 0.002%
SLEW RATE = 2.5V/sec
PSRR = 112dB
IF (R6/R4 = R7/R5) THEN CMRR = 120 dB
ADJUST R7 FOR MAXIMUM CMRR
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GAIN = 100
GAIN LIN = 0.002%
SLEW RATE = 2.5V/sec
PSRR = 112dB
IF (R6/R4 = R7/R5) THEN CMRR = 120 dB
ADJUST R7 FOR MAXIMUM CMRR
Click para ampliarLMC6062 Instrumentation Amplifier
Useful for +5-V single-supply applications, this op amp circuit features low drain (around 1mA), high input resistance (10 e14 ), and low bias current (10 e-14 A).
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Click para ampliarLM6218 High Speed Instrumentation Amplifier
This amplifier features 400-usec settling time (to 0.01%), 140-V/msec slow rate, and 17-Mhz gain-bandwidth product. The supply voltage can be 5 to 20 V.
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Click para ampliarLevel Shifting Isolation Amplifier
The 2N4341 JFET is used as a level shifter between two op amps operated at different power supply voltages. The JFET is ideally suited for this type of application because Id = Is.
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High Gain Differential Instrumentation Amplifier
This circuit includes input guarding, cable bootstrapping, and bias current compensation. Differential bandwidth is reduced by C1 which also makes common-mode rejection less dependent on matching of input amplifiers.
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Click para ampliarExtended Common Mode Instrument Amplifier
These circuits allow a larger common-mode range than most instrument amplifier inputs can allow.
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Click para ampliarBattery Powered Buffer Amplifier for Standard Cell
This circuit has negligible loading and disconnects the cell for low supply voltage or overload on output. The indicator diode extinguishes as disconnect circuitry is activated.
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