Musical Light Chaser

This music-operated lighting effect generator comprises five sets of 60W bulbs that are ranged in zig-zag fashion. The bulb sets glow one after another depending on the intensity of the audio signal. No electrical connection is to be made between the music system and the lighting effect generator circuit. You just need to place the gadget near the

speakers of the music system. Fig. 1 shows the complete circuit  of the musical light chaser, while Fig.2 shows pin configurations of 9V regulator 7809, triac BT136 and level meter IC LB1403.      

The circuit is powered by regulated 9V DC. The AC mains is stepped down by transformer X1 to deliver a secondary output of 12V AC at 250 mA. The transformer output

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Video Signal Amplifier

General Description

Video cassette recorders are becoming ever so popular and as it was to be expected the market is flooding with accessories that make the use of the VCR easier and enhance its operation. The circuit that we offer to you here is a broad band amplifier which will take the video signals from your VCR and will amplify them sufficiently to drive up to 3 monitors, TV sets (provided that they can accept direct video signals), or other VCR�s for recording from one video to up to three others. It will also make possible to record from one video to two others and at the same time have a monitor connected to check what you are recording. The

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Wireless Audio-Video Transmission

This circuit provides you with wireless audio and visual transmission to a TV. The TV acts as a receiver, eliminating the need to buy a separate monitor. You can also hook it up to a VCR or CCD Camera, and even set up a remote CCTV security system!

fig: Block Diagram

Circuit Analysis:

Q3, VC1, C13, C16 and L3 all make up a colpitts oscillator circuit that fluctuates form 220~250MHz. You can regulate the frequency to any value within this threshold by tuning VC1 or L3. C13 modulates the signal rate. When the capacitance increases, so does the modulation. R9 and C16 bias the local oscillation. If you lower R9's frequency to 680W the oscillator's output

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4 Watt FM Transmitter

General Description

This is a small but quite powerful FM transmitter having three RF stages incorporating an audio preamplifier for better modulation. t has an output power of 4 Watts and works off 12-18 VDC which makes it easily portable. It is the ideal project for the beginner who wishes to get started in the fascinating world of FM broadcasting and wants a good basic circuit to experiment with.

Technical Specifications - Characteristics

Modulation type: ........ FMFrequency range: .... 88-108 MHzWorking voltage: ..... 12-18 VDCMaximum current: ....... 450 mAOutput power: ............ 4 W

How it Works

As it has already been mentioned the transmitted signal is Frequency Modulated (FM) which means that the carrier�s amplitude stays constant and its frequency

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Clap Switch

The circuit shown here for clap operated switch is inexpensive and easy to assemble by hobbyists of any level. Clap sound signals picked up by condenser microphone are first amplified by transistor T1, which is a simple common-emitter amplifier. Amplified signals are rectified by diode D1. Positive half cycle of clap signal is applied to a 3-stage DC amplifier formed by transistors T2, T3 and T4. Output from transistor T4 is used as a clock for flip-flop IC1 (7472). For each clap, the output of IC 7472 toggles alternately to on/off state.

Transistor T5 functions as relay driver since output level of IC1 is insufficient to drive a relay directly. The entire circuit, except the relay driver,

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VGA to TV Converter

Here is the circuit for VGA to scart connection. It is basically a circuit which takes VGA signals and converts it to RGB + composite sync signal which can be fed to TV via SCART connector. VGA card picture components RED, GREEN and BLUE are already at the correct voltage level (0.7Vpp) and has correct impedance (75 ohm) for direct connection to correspondign inputs in the TV. What needs to be done is to combine separate horizonal and vertical sync signal from VGA card to one composite sync signal which is feed to TV video in pin in SCART connector. This sync signal conversion is done by the electronics in the circuit. The circuit has also sends correct level

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4 Channel Tranceiver

This is a very simple RF transmitter circuit that consists of the Holtek HT-12E encoder chip and AM 418MHZ-transmitter module (WZ-X01). Using the hybrid RF xmit/receive modules make building the RF remote control a lot easy.

The transmitter can be powered with any voltage from +3 to +12V. The total current consumption is less than 5ma. Depending on the supply voltage, you may need to select a difference resistance value for the oscillator resistor R1. The recommended oscillator is Foscd (decoder) = 50 Fosce (encoder). See data sheet for more details.

The individual security code of the transmitter is preset by dip-switches S5, up to 256 combinations.

When any of S1-S4 is pressed the /TE pin is pulled low, and

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