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,..
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.....
This wide-range light dimmer circuit uses a unijunction transistor and a pulse transformer to provide phase control for the TRIAC. The circuit operates from a 115 volt, 60 Hz source and can control up to 800 watts of power to incandescent lights. The power to the lights is controlled by varying the conduction angle of the TRIAC from 0Â° to about 170Â°.
Using a heatsink, the TRIAC (TR1) can handle up to 350 watts. The neon lamp, II, won't trip the gate until after it conducts and using Rl, set the lighting wherever you want it.
This cross fader circuit can be used for fading between two slide projectors. As R3 is moved to either side of center, one triac is fired earlier in each half cycle, and the other iater.
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 Cl for Ul, which is a free-running multivibrator whose frequency is determined by Rl, R2, R3, R4, and C2.
A phase-controlled triac (HT-32) circuit provides control of effective voltage at load. Do not omit LI and C4 be..
A Seimens SLB0586A IC allows the construction of a simple touch-controlled dirrauer circuit. The circuit controls a triac ac switch,..
A full range power controller suitable for lamp dimming and similar applications operate from a 120 volt, 60 Hz ac source, and can control up to 1000 watts of power to incandescent bulbs. The power to the bulbs is varied by controlling the conduction angle of TRIAC Ql. At the end of each positive half-cycle when the applied voltage drops below that of the capacitor, gate current flows out of the SBS and it switches on, discharging the capacitor to near zero volts. The RC.....
Lamp II is a household lamp. When the switch is in the center position, the lamp is operated on half-wave rectified ac; the ef..
The zener provides a constant voltage of 20 V to unijunction transistor Ql, except at the end of each half-cycle of the input when the line voltage drops to zero. Initially, the voltage across capacitor Cl is zero and capacitor C2 cannot charge to trigger Ql. Cl will begin to charge, but because the voltage is low, C2 will be charged to a voltage adequate to trigger Cl only near the end of the half cycle. Although the lamp resistance is low at this time, the voltage.....
This very special mains-operated dimmer for domestic or industrial lights is not available in proprietary form: it ena..
The dimmer circuit in Figure 1 can change the intensity of the light from zero to maximum. The dimmer operates at approximately 12V, unlike the usual ones that function by adjusting the firing angle of the 110 or 220V mains supply.
The dimmer works to inject a constant current into the halogen lamp and to regulate that current using pulse-width modulation (PWM) according to a potentiometer-controlled input, or a 0 to 5V signal, or even an analog output from a µC. 12V ac.....
With this circuit we can change the brightness of lamb, with a only key of touch. The key of touch is connected in the circuit, center of which is a special completed IC1, which is the S566B of SIEMENS. This IC, it processes the information of duration of touch and then it checks the brilliance of lamb, according to this information. If we touch upon the key for a small period of time (60 until 400 ms), the lamb simply only changes situation, that is to say from OFF in ON.....
Microprocessor control of one 20 watt halogen lamp. Three power levels (7 / 10 / 20 watts). Single pushbutton control for on/off and power level. The PIC16F84 chip is re-programmable, allowing unlimited changes to the basic code. Connect a 12 volt 20 watt lamp and 12 volt battery to the circuit (observe battery polarity). Momentarily press and release the button to turn the lamp on. Repeatedly press the button to cycle through the power levels. Pressing and holding the.....
The circuit is directly connected to the AC power line and should be placed inside an enclosure that will prevent direct contact with any of the components. To avoid electrical shock, do not touch any part of the circuit while it is connected to the AC power line. A 2K, 10 watt power resistor is used to drop the line voltage down to 9 volts DC. This resistor will dissipate about 7 watts and needs some ventilation. In this circuit, an SCR is used to slowly vary the.....
This circuit is a real core of the dimmer system. This circuit generates ramp 100 Hz signal which is syncronized to the incoming mains voltage. The ramp signal which is generated will start form 10V and go linearly down to 0V in 10 milliseconds. At the next mains voltage zero crossing the ramp signal will again immediatly start from 10V and go down to 0V. This same ramp signal is fed to all of the 4 comparators in the dimmer...
Virtually all domestic and professional dimming systems are based on triacs. These devices will conduct once they have been fired, only while current flows in excess of the holding current of the device. These dimmers work very well with a resistive load such as an ordinary Tungsten filament light bulb as the triac can be fired at any point during the mains half-cycle and will continue to conduct until very close to the end of the half-cycle as current is drawn.....
This must generate an awfull lot of RFI without a choke! The house wiring supplies the di/dt limiting. This is a CHEAP design which exhibits hysterisys at dim settings. Not everything made and sold to the public is top notch...
This design has a low duty cycle to preserve battery life and underdrives the cold filament to extend bulb life, however it doesn`t flash well on a near dead battery. The circuit below has a higher duty cycle and drives the cold filament a bit harder. It seems to work well with near-dead batteries too...
Transmitters & Receivers
Sensors & Detectors
Low Frequency Amplifiers
Regulated Power Supplies