555 timer bassed Metal detector circuit with explanation

A very simple metal detector electronic project can be designed using a simple 555 timer integrated circuit . As you can see in the schematic circuit , this electronic project requires few external electronic parts .

This circuit detects metal and also magnets. When a magnet is brought close to the 10mH choke, the output frequency changes.
This metal detector project can be powered from a power supply that can provide an output DC voltage between 6 an 12 volt .
If a metal is closer to the L1 coil , will produce a change of output oscillation frequency, that will generate a sound in the 8 ohms speaker .

readmore: electroniq.net/other-projects/detectors/metal-detector-using-555-timer-circuit.html

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TDA1519C 11W Stereo 22W Mono Power Amp Diagram Circuit

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.

11W Stereo Amplifier Circuit Diagram

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.

22W Stereo Amplifier Circuit Diagram

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.

Mute/Standby Switch Circuit Diagram

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

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1500 W Cobra Power Inverter 12VDC to 120VAC

Power Inverter manufactured by Cobra, capable converting input battery 12VDC to become 120VAC with power loads (output) up to 1500W.

This inverter gives household power on the go. It converts battery power to 120 V AC household power, permitting you to power up office equipment and household appliances from your vehicle. This unit is ideal for such appliances as microwave ovens (1000 watts or much less), coffeemakers, laptops, TVs, video game consoles, CD and DVD players, cell phone chargers, and far more.

How The Cobra Power Inverter Works
The Cobra power inverter is an electronic item that has been created and built to take low-voltage DC (Direct Current) power from your automobile or other low-voltage power supplies and convert it to standard 115 volt AC (Alternating Current) power like the current youve inside your residence. This conversion process thereby allows you to make use of numerous of your household appliances and electronic goods in automobiles, RVs, boats, tractors, trucks, and practically anywhere else.

Cobra 1500 Watt Output Waveform
Some quite sensitive electronic equipment could not operate satisfactorily on "square wave" or "modified sine wave" power. The output waveform of the Cobra Inverter is actually a "square wave" or "modified sine wave." It truly is a stepped waveform created to have characteristics similar to the sine wave shape of utility power. A waveform of this nature is suitable for most AC loads, including linear and switching power suppliers used in electronic equipment, transformers, and motors.

AC receptacles
With three ground AC receptacles, you can connect and power multiple devices at as soon as.

USB Output
The 5-Volt USB output permits charging and operation of modern portable devices, for example iPods, BlackBerrys, and cell phones.

Remote On/Off Switch Capable
An optional Remote On/Off Switch could be connected to the Remote Jack, allowing you to turn the Cobra power inverter on or off from a convenient location when the inverter is installed out of reach.

Safety Features
The CPI 1575 will notify you with a flashing meter and alarm sound when there is a power issue, and will shut down for protection in the following situations:

• Current Overload Protection--If the inverter is overloaded, itll shut down to protect itself.
• Short Circuit Protection--If the AC output of the inverter is short-circuited for 1 second or more, it is going to shut down to safeguard itself.
• Low Voltage Protection--If the input voltage drops to 10.0V or much less, the inverter will shut down to protect itself.
• High Voltage Protection--If the DC input voltage rises above 15.0V, the inverter will shut down to safeguard itself.
• Over Temperature Protection--If the internal temperature rises to 40 degrees C (104 degrees F), the inverter will shut down to safeguard itself. 

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Remote Mains Switch Low Voltage Diagram Circuit

This circuit allows a 240V mains appliance to be controlled remotely via low-voltage cabling and a pushbutton switch. The mains appliance (in this case, a light bulb) is switched with a suitably-rated relay. All of the electronics is housed in an ABS box located in proximity to the appliance. The pushbutton switch and plugpack are located remotely and can be wired up with 3-core alarm cable or similar. Cable lengths of 20m or more are feasible with this arrangement. When the switch (S1) is pressed, the input (pin 8) of IC1c is briefly pulled low via the 10mF capacitor, which is initially discharged.

Circuit diagram:

Low-Voltage Remote Mains Switch Circuit Diagram

The output (pin 10) immediately goes high and this is inverted and fed back to the second input (pin 9) via another gate in the quad NAND package (IC1d). In conjunction with the 1MW resistor and 470nF capacitor, IC1d eliminates the effects of contact "bounce" by ensuring that IC1c’s output remains high for a predetermined period. The output from IC1c drives the clock input of a 4013 D-type flip-flop (IC2). The flipflop is wired for a "toggle" function by virtue of the Q-bar connection back to the D input. A 2.2MW resistor and 100nF capacitor improve circuit noise immunity. Each time the switch is pressed, the flipflop output (pin 13) toggles, switching the transistor (Q1) and relay on or off. Note that all mains wiring must be properly installed and completely insulated so that there is no possibility of it contacting the low-voltage side of the circuit.

Author: Bob Hammond - Copyright: Silicon Chip Elecronics

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Mouse keyboard Switch Unit Diagram Circuit

Unplugging or re-connecting equipment to the serial COM or PS2 connector always gives problems if the PC is running. Even if you only need to swap a mouse or changeover from a graphics keyboard to a standard keyboard. The chances are that the connected equipment will not communicate with the PC, it will always be necessary to re-boot. If you are really unlucky you may have damaged the PC or the peripheral device. In order to switch equipment successfully it is necessary to follow a sequence. The clock and data lines need to be disconnected from the device before the power line is removed. And likewise the power line must be connected first to the new device before the clock and data lines are re-connected.

This sequence is also used by the USB connector but achieved rather more simply by using different length pins in the connector. The circuit shown here in Figure 1 performs the switching sequence electronically. The clock and data lines from the PC are connected via the N.C. contacts of relay RE2 through the bistable relay RE1 to connector K3. Pressing push-button S1 will activate relay RE2 thereby disconnecting the data and clock lines also while S1 is held down the semiconductor switch IC1B will be opened, allowing the voltage on C4 to charge up through R4. After approximately 0.2 s the voltage level on C4 will be high enough to switch on IC1A, this in turn will switch on T1 energizing one of the coils of the bistable relay RE1 and routing the clock, data and power to connector K2.


When S1 is released relay RE2 will switch the data and clock lines through to the PC via connector K1. It should be noted that the push-button must be pressed for about 0.5s otherwise the circuit will not operate correctly. Switching back over to connector K3 is achieved similarly by pressing S2. The current required to switch the relays is relatively large for the serial interface to cope with so the energy necessary is stored in two relatively large capacitors (C2 and C3) and these are charged through resistors R1 and R6 respectively. The disadvantage is that the circuit needs approximately 0.5 minute between switch-overs to ensure these capacitors have sufficient charge.

The current consumption of the entire circuit however is reduced to just a few milliamps. The PCB is designed to accept PS2 style connectors but if you are using an older PC that needs 9 pin sub D connectors then these will need to be connected to the PCB via flying leads. In this case the mouse driver software configures pin 9 as the clock, pin 1 as the data, pin 8 (CTS) as the voltage supply pin and pin 5 as earth.

Resistors:
R1 = 2kΩ2
R2 = 47kΩ
R3 = 10kΩ
R4 = 4kΩ7
R5 = 1kΩ
R6 = 1kΩ2
Capacitors:
C1 = 10µF 10V radial
C2 = 1000µF 10V radial
C3 = 2200µF 10V radial
C4 = 2µF2 10V radial
Semiconductors:
D1-D5 = 1N4148
T1 = BC547
IC1 = 4066 or 74HCT4066
Miscellaneous:
RE1 = bistable relay 4 c/o contacts
RE2 = monostable relay 2 c/o contacts
K1,K2,K3 = 6-way Mini-DIN socket (pins at 240°, PCB mount
S1,S2 = push-button (ITTD6-R)

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Petrol Gas Switch For A Pajero Diagram Circuit

My current vehicle, a Pajero, was modified for dual fuel - ie, petrol and gas. However, its necessary to run the vehicle on petrol at regular intervals to stop the injectors from clogging up. This simple circuit allows the vehicle to be started using petrol and then automatically switches it to gas when the speed exceeds 45km/h and the brake pedal is pressed. Alternatively, the vehicle may be run on petrol simply by switching the existing petrol/gas switch to petrol. You can also start the vehicle on gas by pressing the brake pedal while starting the vehicle. The circuit is based on an LM324 dual op amp, with both op amps wired as comparators. It works like this: IC1a buffers the signal from the vehicles speed sensor and drives an output filter network (D1, a 560kO resistor and a 10µF capacitor) to produce a DC voltage thats proportional to the vehicles speed.

Circuit diagram:

This voltage is then applied to pin 5 of IC1b and compared with the voltage set by trimpot VR1. When pin 7 of IC1b goes high, transistor Q1 turns on. This also turns on transistor Q2 when the brake pedal is pressed (pressing the brake pedal applies +12V from the brake light circuit to Q2s emitter). And when Q2 turns on, relay 1 turns on and its contacts switch to the gas position. Trimpot VR1 must be adjusted so that IC1bs pin 7 output switches high when the desired trigger speed is reached (ie, 45km/h). In effect, the speed signal is ANDed with the brake light signal to turn on the relay. The vehicle has been running this circuit for several years now and is still running well, with no further injector cleans required.

Author: J. Malnar - Copyright: Silicon Chip Electronics

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Mini Guitar Bass Amplifier Diagram Circuit

Output power: 6W into 4 Ohm load, FET input stage - Passive Tone Control
Tiny, portable Guitar Amplifiers are useful for practice on the go and in bedroom/living room environment. Usually, they can be battery powered and feature a headphone output. This project is formed by an FET input circuitry, featuring a High/Low sensitivity switch, followed by a passive Tone Control circuit suitable to Guitar or Bass. After the Volume control, a 6W IC power amplifier follows, powered by a 12-14V dc external supply Adaptor or from batteries, and driving a 4 Ohm 10 or 13cm (4"/5") diameter car loudspeaker. Private listening by means of headphones is also possible.

Circuit diagram:

Mini Guitar-Bass Amplifier Circuit Diagram

Parts:

P1______________1M Linear Potentiometer
P2____________100K Log Potentiometer
R1_____________68K 1/4W Resistor
R2____________470K 1/4W Resistor
R3______________2K7 1/4W Resistor
R4______________8K2 1/4W Resistor
R5____________680R 1/4W Resistor
R6____________220K 1/4W Resistor
R7_____________39R 1/4W Resistor
R8______________2R2 1/4W Resistor
R9____________220R 1/4W Resistor
R10_____________1R 1/4W Resistor
R11___________100R 1/2W Resistor
R12_____________1K5 1/4W Resistor
C1____________100pF 63V Polystyrene or Ceramic Capacitor
C2,C5,C9,C14__100nF 63V Polyester Capacitors
C3____________100µF 25V Electrolytic Capacitor
C4_____________47µF 25V Electrolytic Capacitor
C6______________4n7 63V Polyester Capacitor
C7____________470pF 63V Polystyrene or Ceramic Capacitor
C8______________2µ2 25V Electrolytic Capacitor
C10___________470µF 25V Electrolytic Capacitor
C11____________22nF 63V Polyester Capacitor
C12__________2200µF 25V Electrolytic Capacitor
C13__________1000µF 25V Electrolytic Capacitor
D1______________3mm red LED
Q1____________BF245 or 2N3819 General-purpose N-Channel FET
IC1_________TDA2003 10W Car Radio Audio Amplifier IC
SW1,SW2________SPST toggle or slide Switches
J1____________6.3mm Mono Jack socket
J2____________6.3mm Stereo Jack socket (switched)
J3_____________Mini DC Power Socket
SPKR__________4 Ohm Car Loudspeaker 100 or 130mm diameter

Notes:

• Connect the output Plug of a 12 - 14V dc 500mA Power Supply Adaptor to J3
• Please note that if the voltage supply will exceed 18V dc the IC will shut down automatically

Technical data:

Output power (1KHz sinewave):
6W RMS into 4 Ohm at 14.4V supply
Sensitivity:
50mV RMS input for full output
Frequency response:
25Hz to 20kHz -3dB with the cursor of P1 in center position
Total harmonic distortion:
0.05 - 4.5W RMS: 0.15% 6W RMS: 10%

Tone Control Frequency Response:

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LM2876 40W audio power amplifier Diagram Circuit

Using the LM2876 high-performance audio power amplifier circuit can be designed a very simple high efficiency power audio amplifier electronic project capable of delivering 40W of continuous average power to an 8Ω load with 0.1% THD+N from 20Hz–20kHz.
The performance of the LM2876 high-performance audio power amplifier, utilizing its Self Peak Instantaneous Temperature (°Ke) (SPiKe™) protection circuitry, puts it in a class above discrete and hybrid amplifiers by providing an inherently, dynamically protected Safe Operating Area (SOA). SPiKe protection means that these parts are completely safeguarded at the output against overvoltage, undervoltage, overloads, including shorts to the supplies, thermal runaway, and instantaneous temperature peaks.
The LM2876 maintains an excellent signal-to-noise ratio of greater than 95dB (min) with a typical low noise floor of 2.0μV.

As you can see in the circuit diagram , this 40W high-performance audio power amplifier electronic project require few external electronic parts and require few knowledge .
The muting function of the LM2876 allows the user to mute the music going into the amplifier by drawing less than 0.5 mA out of pin 8 of the device.
Upon system power-up the under-voltage protection circuitry allows the power supplies and their corresponding caps to come up close to their full values before turning on the LM2876 such that no DC output spikes occur.
The LM2876 contains overvoltage protection circuitry that limits the output current to approximately 4Apeak while also providing voltage clamping, though not through internal clamping diodes.
The LM2876 has a sophisticated thermal protection scheme to prevent long-term thermal stress to the device. When the temperature on the die reaches 165°C, the LM2876 shuts down. It starts operating again when the die temperature drops to about 155°C
The LM2876 high-performance audio power amplifier circuit operates over a wide input voltage range , from 20 up to 70 volts , but typically a dual 30 volt power supply ( or a single 60 volt in this case ) will be work fine

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Supply Voltage Monitor Diagram Circuit

A circuit for monitoring supply voltages of ±5 V and ±12 V is readily constructed as shown in the diagram. It is appreciably simpler than the usual monitors that use comparators, and AND gates. The circuit is not intended to indicate the level of the inputs. In normal operation, transistors T1 and T3 must be seen as current sources. The drop across resistors R1 and R2 is 6.3 V (12 –5 –0.7). This means that the current is 6.3mA and this flows through diode D1 when all four voltages are present. However, if for instance, the –5 V line fails, transistor T3 remains on but the base-emitter junction of T2 is no longer biased, so that this transistor is cut off. When this happens, there is no current through D which then goes out.

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with ICL7107 Voltmeter Diagram Circuit

This is volt meter with ICL7107(Analogue to Digital Converter). It has been designed as a panel meter and can be used in DC power supplies or anywhere else it is necessary to have an accurate indication of the voltage present.

Source:macoprojects Schematic: Voltmeter with ICL7107

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