Diagram Plus guide

An amplifier to drive low to medium impedance headphones built using discrete components.

Both halves of the circuit are identical. Both inputs have a dc path to ground via the input 47k control which should be a dual log type potentiometer. The balance control is a single 47k linear potentiometer, which at center adjustment prevents even attenuation to both left and right input signals. If the balance control is moved towards the left side, the left input track has less resistance than the right track and the left channel is reduced more than the right side and vice versa. The preceding 10k resitors ensure that neither input can be "shorted" to earth.

Circuit diagram:

Headphone Amplifier Circuit Diagram

Amplification of the audio signal is provided by a single stage common emitter amplifier and then via a direct coupled emitter follower. Overall gain is less than 10 but the final emitter follower stage will directly drive 8 ohm headphones. Higher impedance headphones will work equally well. Note the final 2k2 resistor at each output. This removes the dc potential from the 2200u coupling capacitors and prevents any "thump" being heard when headphones are plugged in. The circuit is self biasing and designed to work with any power supply from 6 to 20 Volts DC.

Source : www.extremecircuits.net

Circuit Diagram:

 Active High Pass Filter Circuit Diagram

This is active high pass filter circuit for 327Hz frequency using LM741. It will use to build Harmonic at 3 of 130.81 frequency have the value at least. More than the frequency Fundamental 30 dB, for output be sawtooth wave form for use in sound of music way system Electronic design will use the circuit filters three rank frequency. By have 3 dB you slopes can use Op-amp IC number LM741 or number LF351it will meet the frequency well.

Source: ElecCircuit

Using just two NAND or inverter gates its possible to build a D type (or ‘toggle’) flip-flop with a push-button input. At power-up the output of gate N2 is at a logical ‘1’, ensuring that transistor T2 is switched off. When the push-button is pressed the output of N2 changes to a logical ‘0’ and transistor T2 conducts. The coupling between N1 and N2 ensures that the output of N1 will always be the inverse of N2 so T1 and T2 will always be in opposite states and will flip each time the push-button is pressed. In some cases it is possible to omit T1 and T2 and use the outputs of N2 and N1 to drive external circuitry directly but only if the loading on these outputs is low enough.

The 4000 series CMOS family can source/sink a maximum of 0.5mA (at 5 V) so for the sake of safety its best to use these open-collector configured transistor buffers. This circuit is particularly useful if you have some unused gates left over in a circuit design, avoiding the need to add a dedicated flip-flop IC. It is worth remembering that all other unused CMOS gates must have their inputs connected to either the positive or ground rail. The supply voltage can be in the range 3 V to 15 V for CMOS ICs and the current taken by this circuit is between 0.2 mA and 5 mA (no load).

Integrated AF power amps have seen great improvements in recent years offering improved power and easier use. The TDA1519C from Philips contains two power amplifiers providing 11 W per channel stereo or 22 W mono when the two channels are connected in a bridge configuration. The special in-line SIL9P package outline allows the chip to be conveniently bolted to a suitable heatsink. The TDA1519CSP is the SMD version, in this case the heat sink is mounted over, and in contact with, the top surface of the chip.

The operating voltage of this device is from +6V to +17.5V. The two channels of the amplifier are different in that one channel, between pins 1 and 4, is a non-inverting amplifier, while the other between pins 9 and 6 is an inverting amplifier. It is therefore necessary in stereo operation, to wire the speakers so that one of them has its polarity reversed. Each amplifier has an input impedance of 60kΩ and a voltage gain of 40dB, i.e. 100 times. When both amplifier are used in a bridge configuration, the inputs are in parallel so that the input impedance will be 30kΩ.

A combined mute/standby function is provided on pin 8. In its simplest form this can be connected to the positive rail via a switch. When the switch is open the amplifier will be in standby mode and current consumption is less than 100µA. When the switch is closed, the amplifier will be operational. A circuit is also shown that uses the mute input to prevent the annoying switch-on plop heard when power amps are first switched on This is caused by the rush of current to charge capacitors C1 and C2.

The circuit shown generates a ramp voltage, which is applied to pin 8. At switch on, as the voltage rises from 3.3 V to 6.4 V, the amplifier will switch out of standby mode and into mute mode allowing C1 and C2 to charge. Only when the ramp voltage on pin 8 reaches 8.5V will the amplifier switch into active mode. Protection built into the TDA1519C would seem to make it almost foolproof. The two outputs can be shorted to either of the supply rails and to each other. A thermal shutdown will prevent overloading and the power supply input is protected against accidental reversal of the supply leads up to 6V.

An amplifier to drive low to medium impedance headphones built using discrete components.

Both halves of the circuit are identical. Both inputs have a dc path to ground via the input 47k control which should be a dual log type potentiometer. The balance control is a single 47k linear potentiometer, which at center adjustment prevents even attenuation to both left and right input signals. If the balance control is moved towards the left side, the left input track has less resistance than the right track and the left channel is reduced more than the right side and vice versa. The preceding 10k resitors ensure that neither input can be "shorted" to earth.

Amplification of the audio signal is provided by a single stage common emitter amplifier and then via a direct coupled emitter follower. Overall gain is less than 10 but the final emitter follower stage will directly drive 8 ohm headphones. Higher impedance headphones will work equally well. Note the final 2k2 resistor at each output. This removes the dc potential from the 2200u coupling capacitors and prevents any "thump" being heard when headphones are plugged in. The circuit is self biasing and designed to work with any power supply from 6 to 20 Volts DC.