A flashing light of high brightness and short duty cycle is often desired to provide maximum visibility and battery life. This necessitates using an output transistor, which can supply the cold filament surge current of the lamp while maintaining a low saturation voltage. ..
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,..
Assume the correct phase sequence to be VA-VB-VC. The circuit terminals are connected such that Tl gets connected to phase A and T2 to phase B. The capacitor advances the voltage developed across R2 due to phase "B" by — 60°, while the voltages developed across it by phase "A" is in phase with VA as shown in Fig. 69-1. The net voltage developed across R2 ~ zero, the neon lamp is not energized, thereby signaling correct phase sequence. If terminal T2 gets.....
The problem with using two zeners back to back in series to get symmetrical clamping is that the knee of the..
A neon lamp can easily be added to the phone line to act as a ring indicator...
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. ..
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 unit consists of rlamplifier Q1, local oscillatorQ2, and mixer Q3. The two bands are covered without a bandswitch by using an i-f or 3.5 MHz. The oscillator range is 7.5 to 14.5 MHz. Incoming signals from 4 to 11 MHz are mixed with the oscillator to produce the 3.5-MHz i-f. Signals from 11 to 18 MHz are mixed with the oscillator to also produce an i-f of 3.5 MHz. At any one oscillator frequency, the two incoming signals are 7 MHz apart. ..
For back-lit LCD displays, this supply will drive a lamp. LT1072 drives Ql and Q2, and a sine wave app..
One lamp at a time is lit in the string to give the appearance of a moving point of light. ..
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 astable multivibrator uses incandescent lamps in place of collector load resistors. ..
When operated as an open loop without compensation, the HA-2400 becomes a comparator with four selectable input channels. The clamping network at the compensation pin limits the output voltage to allow DTLor TTL digital circuits to be driven with a fanout of up to ten loads. The circuit can be used to compare several signals against each other or against fixed references; or a single signal can be compared against several references. ..
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..
The pseudorandom sequencer drives a solid-state relay. If you power a low-wattage lamp from the re..
Zener diode ZD1 senses the supply, and should the supply rise above 6 V, Ql will turn on. In turn, Q2 conducts clamping the rail. Subsequent events depend on the source supply. It will either shut down, go into current limit or blow its supply fuse. None of these will damage the TTL chips..
You can turn any ordinary household bulb into one that shimmers or blinks. This circuit works on any incandescent light up to 200 W, arid runs on standard 120 Vac. The circuit uses an SCR to cause an ordinary lamp to sliimmer. 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 1)2. That.....
Initially the neon and xenon lamps are not conducting and act like a very high (almost infinite) resistance. Capacitors Cl and C4 in conjunction with DI and D2 form a voltage doubler circuit, which can charge C2 up to about 300 Vdc after several ac cycles. Voltage increases as current is supplied through Rl and R2. Neon bulb II will all of a sudden start to conduct when the voltage across C3 reaches II's ionization potential. While conducting, the resistance of the bulb.....
Put the car in reverse and the circuit provides a loud, audible beep at the rate of about one per second (1Hz). Half of U1, a 556 dual oscillator/timer, is used as a slow-pulse oscillator with a rate of about 1Hz. Components R2, R1, and C1 form the long time constant. You can calculate on time by t~.7 (R1 + R2) C1 or 1.15 seconds. The off time is shorter than the on time, at . 77 second. Enabling pin 4 (reset) is held high to keep the oscillator freerunning when voltage is.....
The regulator delivers 100-V at 100 mA and withstands shorts to ground. Even at 100 V output, the LT317A functions in the normal mode, maintaining 1.2 V between its output and adjustment pin. Under these conditions, the 30-V zener is off and Ql conducts. When an output short occurs, the zener conducts, forcing Q1"s base to 30 V. This causes Q1"s emitter to clamp 2 VnEs below Vz. well within the V.w VouT rating of the regulator. ..
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