Identify diagram

Radio signals are a form of electromagnetic wave. They are the same type of radiation as light, ultra-violet and infra red rays, differing from them in their wavelength and frequency. Electromagnetic waves have both electric and magnetic components that are inseparable. The planes of these fields are at right angles to one another and to the direction of motion of the wave. The electric field results from the voltage changes occurring in the antenna which is radiating the signal, and the magnetic changes result from the current flow. It is also found that the lines of force in the electric field run along the same axis as the antenna, but spreading out as they move away from it. This electric field is measured in terms of the change of potential over a given distance, e.g. volts per meter, and this is known as the field strength. Similarly when an antenna receives a signal the magnetic changes cause a current flow, and the electric field changes cause the voltage changes on the antenna.

There are a number of properties of a wave. The first is its wavelength. This is the distance between a point on one wave to the identical point on the next. One of the most obvious points to choose is the peak as this can be easily identified although any point is acceptable.

The second property of the electromagnetic wave is its frequency. This is the number of times a particular point on the wave moves up and down in a given time (normally a second). The unit of frequency is the Hertz and it is equal to one cycle per second. This unit is named after the German scientist who discovered radio waves. The frequencies used in radio are usually very high. Accordingly the prefixes kilo, Mega, and Giga are often seen. 1 kHz is 1000 Hz, 1 MHz is a million Hertz, and 1 GHz is a thousand million Hertz i.e. 1000 MHz. Originally the unit of frequency was not given a name and cycles per second (c/s) were used. Some older books may show these units together with their prefixes: kc/s; Mc/s etc. for higher frequencies.

The third major property of the wave is its velocity. Radio waves travel at the same speed as light. For most practical purposes the speed is taken to be 300 000 000 meters per second although a more exact value is 299 792 500 meters per second. Although wavelength was used as a measure for signals, frequencies are used exclusively today. It is very easy to relate the frequency and wavelength as they are linked by the speed of light as shown:

lambda = c / f

Where, lambda = the wavelength in meters

f = frequency in Hertz

c = speed of radio waves (light) taken as 300 000 000 meters per second for all practical purposes.

It is also interesting to note that close to the antenna there is also an inductive field the same as that in a transformer. This is not part of the electromagnetic wave, but it can distort measurements close to the antenna. It can also mean that transmitting antennas are more likely to cause interference when they are close to other antennas or wiring that might have the signal induced into it. For receiving antennas they are more susceptible to interference if they are close to house wiring and the like. Fortunately this inductive field falls away fairly rapidly and it is barely detectable at distances beyond about two or three wavelengths from the antenna.

The information in this manual supplements the owner manual. This manual describes features that may or may not be on your specific vehicle either because they are options that you did not purchase or due to changes subsequent to the printing of this owner manual. Please refer to the purchase documentation relating to your specific vehicle to confirm each of the features found on your vehicle. For vehicles first sold in Canada, substitute the name “General Motors of Canada Limited” for Chevrolet and GMC Motor Divisions wherever it appears in this manual. download here

The electronic dog repellent circuit diagram below is a high output ultrasonic transmitter which is primarily intended to act as a dog and cat repeller, which can be used individuals to act as a deterrent against some animals. It should NOT be relied upon as a defence against aggressive dogs but it may help distract them or encourage them to go away and do not consider this as an electronic pest repeller. The ultrasonic dog repellant uses a standard 555 timer IC1 set up as an oscillator using a single RC network to give a 40 kHz square wave with equal mark/space ratio.

This frequency is above the hearing threshold for humans but is known to be irritating frequency for dog and cats. Since the maximum current that a 555 timer can supply is 200mA an amplifier stage was required so a high-power H-bridge network was devised, formed by 4 transistors TR1 to TR4. A second timer IC2 forms a buffer amplifier that feeds one input of the H-bridge driver, with an inverted waveform to that of IC1 output being fed to the opposite input of the H-bridge.

Circuit diagram:

Cat And Dog Repellent Circuit Diagram

This means that conduction occurs through the complementary pairs of TR1/TR4 and TR2/TR3 on alternate marks and spaces, effectively doubling the voltage across the ultrasonic transducer, LS1. This is optimised to generate a high output at ultrasonic frequencies. This configuration was tested by decreasing the frequency of the oscillator to an audible level and replacing the ultrasonic transducer with a loudspeaker; the results were astounding. If the dog repellent circuit was fed by a bench power supply rather than a battery that restrict the available current, the output reached 110dB with 4A running through the speaker which is plenty loud enough!

The Dog and Cat repellant was activated using a normal open switch S1 to control the current consumption, but many forms of automatic switching could be used such as pressure sensitive mats, light beams or PIR sensors. Thus it could be utilise as part of a dog or cat deterrent system to help prevent unwanted damage to gardens or flowerbeds, or a battery powered version can be carried for portable use. Consider also using a lead-acid battery if desired, and a single chip version could be built using the 556 dual timer IC to save space and improve battery life.

Source : www.extremecircuits.net

The BMW 325ix was produced from 1988 to 1991, and featured all-wheel drive. It was available as a two-door (saloon) or a four-door (sedan) and as touring.The BMW 325iX wiring diagram electrical schematics following article provides detail procedures for maintaining, inspection, trouble diagnose, and repairing the 1990 BMW 325iX Electrical System.
This manual is divided into following sections: Index, How to Use This Manual, Wire Size Conversion Chart, Wiring Diagram and Electrical Parts Symbols, Systematic Troubleshooting, Connector Views, Power Distribution Box, Fuse Data, Component Location Chart, Component Location View, and Splice Locations Views.

This manual also covers topics on: Power Distribution System, Charging and Starting System, Electronics Injection System, Supplemental Restraint System, Brake Warning System, Antilock Braking System, Power Mirror, Central Locking, Power Windows, Seats, Sunroof, Body Electrical System, Wiper and Washer, Instrument Cluster, Active Check Control, Light Switch Details, Headlight, Turn and Hazard Lights, Heating and Air Conditioning, Radio, Antenna and Power Antenna, etc. Here is a quotation from the voltage drop testing section.

“Wires, connectors and switches are designed to conduct current with a minimum loss of voltage. A voltage drop of more than one volt indicates a problem. To test a voltage drop, connect the voltmeter leads to connectors at either end of circuit’s suspected problem area. The positive lead should be connected to the connector closest to the power source. The voltmeter will show the voltage drop between these two points.”

Find more information about 1990 BMW 325iX Electrical Troubleshooting Manual – Harness and Schematics here. (source: wikipedia.com, armchair.mb.ca)