Due to the low duty cycle of flashing LED, the average current drain is 1 mA or less. The NE555 will trigger the LED on when the monitored voltage falls to 12 volts..
When SI (sensor) is closed, power is applied to U2, a dual timer. After a time determined by C2, CI is ene..
The first amplifier circuit is a bird phone. In this circuit, the electret mike (MIC1) is mounted in the neck of a large plastic funnel. The amplifier, built around an MC34119 (which is available from D.C. Electronics, P.O. Box 3203, Scottsdale, AZ 85271-3203; Tel. 800-467-7736, and elsewhere), is then placed outside of the funnel with the pickup facing a nearby bird feeder. The output of the amplifier is then connected to a 16- speaker. The amplifier`s voltage gain is.....
Integrated circuit Ul (a 555 oscillator/timer) is wired as a conventional pulse generator. The frequency of the pulse generator is controlled by potentiometer Rll. Resistor R2 puts areasonable limit on the highest speed attainable. The output of the pulse generator is fed to the common clock input of U2, a 74C175 quad D-type flip-flop. Each flip-flop is configured so that its Q output is coupled to the D input of the subsequent flip-flop. Information on the D input of.....
This relatively simple, inexpensive circuit requiring one trimming operation can multiply or divide with a consistentaccuracy of greater than 1 part in 1,000. An inexpensive CMOS version of standard 555 timer chip T, in conjunction with low-drift LMll error amplifier A3, an inexpensive analog chopper switch SW, form a unique voltage-to-duty-cycle converter to produce the difficult transfer function necessary for accurate conversion. ..
The PWM controller uses complementary half-H peripheral drivers SN75603 and SN75604, with totem-pole outputs rated at 40 V and 2.0 A. These drivers effectively place the motor in a full-bridge configuration, which has the ability to provide bidirectional control. Timer U1 operates in the astable mode at a frequency of 80Hz. The 100-0 discharge resistor results in an 8-p.s trigger pulse which is coupled to the trigger input of timer U2. Timer U2 serves as the PWM.....
Using two NE555 timer IC devices, this circuit generates either pulsed or continuous ultrasonic signals. The value..
With the 555 timer connected as a multivibrator and an opto-isolator, ..
When power is first applied, three things happen: the light-driving transistor (Ql) is switched on because of a low output from U2, pin 3; timer Ul begins its timing cycle, with the output (pin 3) going high, inhibiting U2`s trigger (pin 2) via D2; and charge current begins to move through R3 and R4 to CI.When Ul`s output goes low, the inhibiting bias on U2 pin 2 is removed, so U2 begins to oscillate, flashing the third light via Ql, at a rate determined by R8, R6, and.....
Output voltage great enough to jump a l-inch gap can be obtained from a 12-V power source. A 555 timer IC is connected as an astable multivibrator that produces a narrow negative pulse at pin 3. The pulse turns Ql on for the duration of the time period. The collector of Ql is direct-coupled to tbe base of tbe power transistor Q2, turning it on during the same time period. ..
The circuit with independent control of "ON" and "OFF" periods uses the CA3130 BiMOS op amp for filters, oscillators, and long-duration timers...
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..
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 heatlight-height. When headlights illuminate the photoresistor, the timer.....
The sensor consists of two series-connected lN914s, part of the circuit of a 555 multivibrator. Wired as shown, the output pulse rate is proportional to the temperature of the diodes..
A CMOS timer generates true square waves because, unlike the bipolar 555, its output swings from rail to rail...
The tone generated by a 555 oscillator can be turned on (activated) by heat or light. That causes Ql to conduct transistor W2 (TIP 3055)...
The circuit uses a 555 timer IC to power an ultrabright LED. The output is a pulsing red light that can be projected using lenses. An ultrabright Stanley LED, capable of 300-millicandle output, is tied to pin 3 of the 555 timer IC. That IC has been configured as an astable multivibrator. The frequency of this multivibrator is controlled by Rl, R2, CI, and PI. You can vary the frequency by adjusting PI, which changes the output from a slow blinking to a fast pulsating light...
In these applications, a pulse input at % is differentiated by a C-R network and the negative-going edge at pin 6 causes the input comparator to trigger the timer circuit. Just as with a V-to-F converter, the average current flowing out of pin 1 is IaverAGE = i (1.1 RjC^ f. In this simple circuit, this current is filtered in the network RL = 100 k ohm and 1 µF. ..
The circuit is basically a NE555 monostable, the only major difference being its method of triggering. The trigger input is biased to a high value by the 22 ohm resistor. When the contact plates are touched, the skin resistance of the operator will lower the overall impedance from pin 2 to ground. This action will reduce the voltage at the trigger input to below the 16 Vcc trigger threshold and the timer will start. ..
The 555 is used in a monostable multivibrator circuit that puts out a fixed timewidth pulse..
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