The circuit is basically a radio frequency (RF) oscillator that operates around 100 MHz. Audio picked up and amplified by the electret microphone is fed into the audio amplifier stage built around the first transistor. Output from the collector is fed into the base of the second transistor where it modulates the resonant frequency of the tank circuit (the 5 turn coil and the trimcap) by varying the junction capacitance of the transistor. Junction capacitance is a function of the potential difference applied to the base of the transistor. The tank circuit is connected in a Colpitts oscillator circuit.

This simple circuit will find many applications as a battery eliminator for low power requirements. It consists of a transformer, a bridge rectifier and an electrolytic capacitor followed by a zener controlled series pass transistor. The output is stabilized at +7.5V. The stand-by battery, 7.5V, in series with D7, floats across the output terminals, ready to take over in case of main failure. The voltage drop across D7 will then reduce the power supply to about 7V. The R3 has an additional function, when working off the mains it will trickle charge the dry cells or storage battery. It?s correct resistance can be found by dividing the voltage potential difference between the zener D6 and the battery by the safe trickle current, which may amount to some 0.7 milliamps.

A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower. The circuit of the device is shown in Figure 2. The water detection is made from the bottom of the circuit in the form of ten copper contacts - inputs to the inverters N1 - N10. These inputs are LOW, about 0 volts, that is, when they are covered with water. Correspondingly, the inverter outputs are HIGH, they are positive. In this situation, the LED diodes D1-D10, as they are connected. Are without potential difference and therefore do not flicker. Only the D11 lights up because its uplink is connected to the N10 output (HIGI) via R24 while its cathode is permanently at 0 volts. Turning on D11 means that the pot has a good amount of water (or moisture).

This amplifier can transfer dc-to 5-MHz signals across a potential difference of 25 000 V. This circu

Hall Effect sensor will produce a voltage proportional to the magnetic field strength received by a Hall effect sensor tersebut. Sensor it only consists of a silicon layer and two electrodes on each side of the silicon. By the time without any influence of the magnetic field then the potential difference between the two electrodes is 0 Volt as an electric current flowing in the middle two electrodes. When there is

found the current in both the loops using Kirchhoff`s Voltage law but then I`m confused on the proper method to find the potential drop between the two loops. I suggest you insert two extra points A and B on both ends of the battery (on the bottom right of the left square and the top left of the right square). Can you calculate the potential difference between X and A, A and B,

The continuity tester can distinguish between high-, medium-, and low-resistance connections. When there is a conductance between the inputs, which are linked to small probes, a current flows from the +9 V line to earth via R1 and R2. The consequent potential difference, p. d. , across R2 is used to determine the transfer resistance. Operational amp

A meter is a measuring instrument. An ammeter measures current, a voltmeter measures the potential difference (voltage) between two points, and an ohmmeter measures resistance. A multimeter combines these functions, and possibly some additional ones as well, into a single instrument. Before going in to detail about multimeters, it is important for

The ICL7106 Integrated circuit contain all the active circuitry for a 3 1/2 digit panel meter (DPM) in a single chip. It was designed to interface directly to a liquid crystal display (LCD). The potential difference across a silicon diode is dependent on its temperature and current through it. Its temperature coefficient is negative, that is, the

The constant current charging circuit which is composed of the three-port voltage stabilizer is as shown in figure 2-21. Because the electric potential difference of the LM317`s pin-1 and pin-2 is 1. 25V, if we ignore the shunting effects of R3, R1, LED, the potentiometer R2 can adjust the charging current value, the constant current value I=1. 25/R