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...
A 4001 CMOS Quad NORgate is set up as an astable multivibrator, which drives a simple differentiator and relay..
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. ..
This circuit is suitable for fitting into slide projectors without a dimmer facility as witb 24-Vac fed halogen lamps. With a few small alterations, it can also be used for dimming 12-V halogen lamps, but not those in a car, because these are fed from a de source. The circuit shown in Fig. 50-1a is intended for operation from a 24-Vac supply, and can handle a lamp load of up to 150 W. For loads up to 250 W, the TIC236 should be replaced by a TIC246. ..
This source is selected by pressing momentary-contact pushbutton switch SI. Switch SI is connected to the trigger of a 555 oscillator/timer (Ul) configured as a monostable multivibrator, wliich generates one short output pulse for each press of SI. That pulse turns on LED1 to give a visible indication that the 555 is working correctly. That pulse is also used to clock U2 (a 4017 CMOS divide-by- 1 -counter/divider). Both LED1 and its associated current-limiting resistor R3.....
This circuit should be useful for interfacing phone projects to the telephone line. ..
With SI open, base bias is supplied to Q2 through a voltage divider (formed by R2 and R3), thus turning on the green element in the LED. That indicates that power is being supplied to the project. If you close SI, current through R1 biases Ql on, thereby grounding the voltage divider and turning off Q2. That reverses the flow of current through the LED, which causes its red element to light. That indicates that the circuit is under power and SI (really a DPDT switch),.....
If your ear is good, you can use this IR-pulse-to-audio converter to troubleshoot infrared remote-controls. It is also a good project for detecting infrared-light sources. A photo cell module (Radio Shack P/N 276-137) detects IR radiation and drives audio IC Ul. ..
The circuit is built around a 4001 quad two-input NOR gate, it provides switch selectable auto-advance times of 5, 10, 15, 20, 25 or 30 seconds through the remote-control socket of your projector. Ula and Ulb form an astable multivibrator, with its operating frequency dependent on the number of timing resistors switched into the circuit via S2. The frequency is about one cycle for every five seconds with a single timing resistor, one every ten seconds with two resistors,.....
The circuit will regulate the rms output voltage across the load (a projection lamp) to 100 volts ±2% for an input voltage between 105 and 250 volts ac. This is accomplished by indirectly sensing the light output of lamp LI and applying this feedback signal to the firing circuit (Ql and Q2) which controls the conduction angle of TRIAC Q3. The lamp voltage is provided by TRIAC Q3, whose conduction angle is set by the firing circuit for unijunction transistor Q2. The.....
Using the TB2922HQ audio power IC can be designed a very simple and high efficiency power audio amplifier electronic project . TB2922HQ is 2ch BTL audio amplifier for TV or home audio applications. It includes and the pure complementary P-ch and N-ch DMOS output stage. This TB2922HQ power audio amplifier project is very simple to be implemented and require few external electronic parts . The TB2922HQ power audio amplifier module can be used with 4 or 8 ohms load . Using a.....
The purpose is supposedly to account for the fact that human hearing is less sensitive at low and high frequencies than in the upper midrange, and that this variation is dependent upon the sound intensity (SPL). The Fletcher-Munson curve (as it is commonly known, and reproduced below) shows the variation, and it is clear that any loss of sensitivity is highly dependent upon the actual SPL. The idea that a single filter can represent this at all levels is clearly wrong, but.....
This is the latest version of the Improved Infrared Receiver with Status LED which can control any desktop PC with an ordinary remote control. The project comes along with a small PCB in order to save space. It connects to the serial port as stated in the schematic and uses the freeware Girder (www.girder.nl) software together with Igor?s Plugin (www.cesko.host.sk/girderplugin.htm) to send commands to the PC. The potential uses of this device are countless (control MP3.....
This project (unlike most of the others) is based almost directly on the "typical application" circuit in the National Semiconductor specification sheet. As it turns out, the typical application circuit is not bad - would I go so far as to say hi-fi in the audiophile sense? Perhaps - with caveats. It has good noise and distortion figures, and is remarkably simple to build if you have the PCB...
This surround-sound decoder is based on the "Hafler" principle, first discovered by David Hafler sometime in the early 1970s. The original idea was to connect a pair of speakers as shown in Figure 1, for use as the rear speakers in the surround setup. This is ok just as it stands, but problems are created if the main speakers are bi-amped or using bridging, for example, since there is no longer a full-range / full power signal available for the rear speakers. This circuit.....
This project is easy enough for beginners, the only difficulties possibly arising from serial port hardware incompatibility from PC to PC. In the single-sensor version, you need only the sensor IC, a voltage regulator and and handful of diodes and resistors. Build it, and learn the secrets of IIC bus, how to implement IIC bus using only two resistors and a couple of zeners, how to drive it on a serial port using Visual Basic..
# This version uses a double sided PCB. Dimensions are approximately the same as the original version. # Removed the second push button switch and components for the RS232 serial interface. # Added 22K resistor between MCLR input and Vdd. This eliminates the need for a jumper on the ICSP header in normal operation. (If you use a 12F683 you can omit this resistor as well since it has an internal pull-up) ..
This is a four-channel temperature measurmet adapter that works without external power supply. It will suitable for measureing temperature and logging its data with a PC. The circuit diagram is very simple and no adjustment is required, everybody will able to build it with ease. I chose an Atmel ATtiny15L for this project. It is the only device that has a built-in 10bit A-D converter in the 8 pin AVRs. The A-D converter has a bandgap reference and differencial amplifire.....
This complete high quality, low noise 5-BAND GRAPHIC EQUALIZER circuit is based around Monolithic Linear integrated circuit LA3600 manufactured by SANYO. This circuit is very easy to build and has good Quality. You can use it with Portable component stereos, tape-recorders, radio-cassette recorders, car stereos etc... It is On-chip one operational amplifier. 5-band graphic equalizer for one channel can be formed easily by externally connecting capacitors and variable.....
This project`s purpose is to design a fully automated machine for drilling a printed circuit board, (PCB) blank at a minimum cost and with the minimum amount of custom machining. This low cost philosophy is achieved by adapting the existing mechanical assemblies from readily available computer peripherals and electronic measuring instruments. Drill data is transferred to the PCDrill from an Excellon drill file generated by a PCB CAD program running on a personal computer...
Operational Amplifiers
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ANSI Standards
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Number Systems
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