TREE

In this circuit power supply is given by Pressing switch Sw(1).when we press the Sw(1) it shorts the N/O contact of relay RL(1) which gives the supply to our circuit.The current which passing thorough resistor R8 gives the base current to transistor T5.Where the transistor T2 and T3 are making darlington pair. A darlington pair has various applications associated with it and one of them is to use it as a switch. As the transistor's collector current is proportionally limited by its base current, it can be used as a current-controlled switch.And transistor T4 ON when over or under voltage is given to transistor T3. Where capacitor C2 is used for avoiding noise.where capacitor C2 with resistor R10 making a low pass filter which also gives us sufficient time delay. There is a resistor network(VR1,R11,R12) which is used as a current sensor.Where zener diode ZD1 and ZD2 are used for the over voltage protection. where capacitor C1 used as a noise filter of switching circuit and Diode D3 ...

When audio is detected, the output is push-pull and consumes less than 3mA (with no signal) but drives the earpiece to a very loud level. It’s extremely difficult to set up because the whole circuit is DC coupled. Basically you don’t know where to start with the biasing. 8k2 between the emitter of the first transistor and 0v rail and the 470R resistor are the two most critical component. The emitter voltage on the BC 547 is set by the 8k2 across the 47u and this turns it on. To call the driver transistor, the collector is directly connected to the base of a BC 557. Current flow through the 1k and 470R resistors so that the voltage developed across each resistor turns on the two output transistors is caused by these transistors and the output of BC 557 are now turned on. The end result is mid-rail voltage on the join of the two emitters.Major negative feedback is provided by 8k2 feedback resistor while the 330p prevents high-frequency oscillations occurring. [Source: Talking Electronics...

Using some power transistors and some other common electronic components, can be designed a high power audio amplifier capable to provide a maximum output power of 90W. This power amplifier based on transistors is capable of provide an output of 70W on a load of 8 ohms or 90W on a 4 ohms load. If the component values in parentheses are used can be connected speakers with 4 ohm impedance, in which case the amplifier maximum output power will be around 90 watts. 90Watts Amplifier Using Transistors Circuit Diagram The input signal is brought to the transistor T1 and the reaction is taken on the basis of T2. Current through deferential stage is kept constant at 1 mA current source through the action of T3. The input signal for T4/T8 transistor is taken from the T1's collector in combination with current source T5 forms a control stage class A for power transistors. Current through control stage is quite small (about 7 mA) as T6 and T9 are Darlington power transistors. Protection ci...

This is a very simple and low-cost Electronic Circuit Project of NiCd charger using with transistors. This NiCd charger allows simultaneous charging of up to seven NiCd batteries connected in series. This number can be increased if the supply voltage increases by about 1.65 V for each battery. NiCad Charger Using with Transistors Circuit Diagram: Given that T2 is mounted on appropriate heat radiator, the input voltage can be increased to a maximum of 25 V. Typically these loads to NiCd batteries a current equal to one tenth of the battery capacity. If current value is greater than indicated, the charging time must be reduced proportionally, to prevent damage to battery elements. The charging current is controlled by P1 between 0 mA to 1A current can be measured with a voltmeter connected parallel of R3 (which, to avoid additional calculations, has value, convenient to 1ohm). Lowering the value of R3, maximum output current can be increased to over 1 A. Circuit consume 15 mA current in ...