Build a Relay Switch Activated by Tone and Signal

The essence of the schema is for the input of tone and signal to provide an activation for the relay switch.

• Relay – an electrically operated switch where the current flowing through the coil of the relay is creating a magnetic field which attracts a lever and changes the switch contacts, thereby making its state open or close
• BC214 – a complementary silicon planar epitaxial transistor used in AF small signal drivers and am1 as well as for low noise preamplifier applications due to its feature of good linearity of DC current gain
• LM741 – a general purpose single operational amplifier with features such as offset null, compensated internal freq uency, voltage range with high input, good stability of temperature, and protected from short schema

The use of relay will allow the schema to switch from one condition to another. It can also be referred to as a form of an electrical amplifier since it is able to control an output schema of higher power than the input schema. There are many types of relays being used in many electronic and electrical diagram, which include solid-state relay, Buchholz relay, overload protection relay, latching relay, forced-guided contacts relay, mercury-wetted relay, contactor relay, machine tool relay, reed relay, polarized relay, and solid state contactor relay.

 Relay Switch Activated by Tone and Signal Circuit Diagram

The schema created is sensitive enough to the AC signals in the input stage, where the signals are ranging above 5 mV. It will also be sensitive to react with the human voice signals having a range of frequency from 50 Hz up to 3 KHz. The human voice is a part of the human sound produced primarily by the vocal cords or vocal folds which in turn produces a voice frequency that is used for the transmission of speech.

During the absence of an input signal, the state of the 12 V relay RL1 is at OFF condition as regulated by the 10K Ohms trimmer RV1. The schema can be made to react with its sensitivity in points A, B, & C, where a negative feedback can be placed due to the addition of band pass filter. The filter will operate only in the 1 KHz range and the schema will only correspond at this frequency.

The signal and tone activated relay switch were used in a wide range of fields which includes measuring instruments, audio systems, communications equipment, and factory-automation equipment. They can also be found on telephone subscriber diagram for the polarity reversing switch, testing, and ringing functions.

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Build a Car Voltage Regulator Circuit Using LM317

The car cigarette lighter socket does not only light cigarettes, but can be utilized as an electrical channel for powering tools to work on the car such as laptops and other electronic devices. The following schema diagram shows a way of powering a two-way mobile radio using the LM317T voltage regulator.

The LM317T is an adjustable 3-terminal positive voltage regulator that efficiently provides a load current of 1.5 Amps over an output range of 1.2 V and 37 V. With reference to the schema, it can accept 14 volts without any hassle and the voltage can be controlled easily with the use of a potentiometer, a 3-terminal resister with sliding contact. The whole schema will contain the following components:

 Printed Circuit Board (PCB)
Resistor 1 (R1): 270 ohms
Resistor 2 (R2): 2K carbon potentiometer
Capacitor 1 (C1): 100nF
Capacitor 2 (C2): 1uF tantalum
LM317T Voltage Regulator
Heat Sink
DC Power Jacks
Green LED: Power
Red LED: Over Voltage
Zener Diode: over voltage LED switch

The zener diode switches on the over voltage LED if the voltage passing through is larger than the breakdown or preset voltage. The use of zener diode permits a constant amount of voltage and can be very beneficial for devices that inputs the same amount of voltage.

LM317T is cheaply available in the market and is very simple to integrate into several energy system to supply a maximum current or voltage.

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How to Build a Photodiode current to voltage converter

The Photodiode current-to-voltage converter schema uses three CA3130 BiMOS op amps in an application sensitive to sub-picoampere input currents. The schema provides a ground-referenced output voltage proportional to input current flowing through the photo-diode.

 Photodiode current-to-voltage converter schema

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Build a Low Ripple Power Supply Wiring diagram Schematic

How to build a low ripple power supply schema diagram. This simple low ripple power supply schema diagram may be used where a high current is required with a low ripple voltage (such as in a high powered class AB amplifier when high quality reproduction is necessary) , Ql, Q2, and R2 may be regarded as a power darlington transistor.

ZDl and Rl provide a reference voltage at the base of Ql. ZDl should be chosen thus: ZDl = Von-1. C2 can be chosen for the degree of smoothness as its value is effectively multiplied by the combined gains of Q1/Q2, if 100 µF is chosen for C2, assuming minimum hfe for Ql and Q2, C = 100 x 15(Q1) x 25(Q2) = 37,000 µf.

Low Ripple Power Supply Circuit Diagram

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Build A 15V Chopper Amplifier Wiring diagram Schematic

This simple schema is a gain-of-1000 inverting amplifier. It will amplify submillivolt signals up to signal levels suitable for further processing. In almost all system applications, it is best to use as OUTPUT much gain as possible in the MAX420, thus minimizing the effects of later-stage offsets. For example, if schemary following the MAX420 has an offset of 5 m V, the additional offset referred back to the MAX420 input (gain = 1000) will be 5 p.V, doubling Fig. 3-4 the system`s offset error.

Build A 15V Chopper Amplifier Circuit Diagram

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Build a Hi Low level Comparator Wiring diagram Schematic

Build a Hi-Low level Comparator Circuit Diagram, The voltage to be compared is fed through diode Dl and D2 to the voltage dividers Rl and R5 where the low and high limits are present. When the voltage level of an input signal exceeds the high threshold limit set with potentiometer Rl, the diode Dl becomes forward biased and the increased voltage on the inputs of the op amp drives it into positive saturation. Similarly, a decrease of the input voltage at the op amp inputs turns the op amp to positive saturation. Potentiometer R3 is used for zeroing the op amp in the off state.

Hi-Low level Comparator Circuit Diagram

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Build a Regulated driven Converter Wiring diagram Schematic

How to Build a Regulated driven Converter Circuit Diagram?.This converter delivers up to 50 mA from a 6-V battery with 78% efficiency. This flyback converter functions by feedback-controlling the frequency of inductive flyback events. The inductor`s output, rectified and filtered to de, biases the feedback loop to establish a stable output. If the converter`s output is below the loop setpoint, A2`s inputs unbalance and current is fed through the 1-MO resistor at Al. This ramps the 1000-pF value positive. When this ramp exceeds the 0.5-V potential at A1 `s positive input, the amplifier switches high. 

 Regulated driven Converter Circuit Diagram

Q2 turns on, discharging the capacitor to ground. Simultaneously, regenerative feedback through the 200-pF value causes a positive-going pulse at A1`s positive input, sustainlljg A1`s positive output. Q1 comes on, allowing inductor, 11, current to flow. When A1`s feedback pulse decays, its output becomes low, turning off Ql. Q1`s collector is pulled high by the inductor`s flyback and the energy is stored in the 100-I`F capacitor. The capacitor`s voltage, which is the schema output, is sampled by A2 to close a loop around Al/Ql. This loop forces A1 to oscillate at whatever frequency is required to maintain the 15-V output. 

In-phase transformer windings for the drain and gate of TMOS power FET Q1 cause the schema to oscillate. Oscillation starts when the feedback coupling capacitor, C1, is charged from the supply line via a large resistance; R2 and R3 limit the collector current to Q2. During pump-up, the on time is terminated by Q2, which senses the ramped source current of Ql. C1 is charged on alternate half-cycles by Q2 and forward-biased by zener D2. 

When the regulated level is reached, forward bias is applied to Q2, terminating the on time earlier at a lower peak current. When this occurs, the frequency increases in inverse proportion to current, but the energy per cycle decreases in proportion to current squared. Therefore, the total power coupled through the transformer to the secondary is decreased.

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Build a Simple Home Alarm Circuit Using 555 ICs

This is a Simple Home Alarm Circuit Using 555 ICs. This schema can be simplified by using a single 74C14 IC. This IC is also known by the following numbers: 40106, 40014, and 74HC14.  These are CMOS chips and are characterised by low current consumption, high input impedance and a supply voltage from 5v to 15v. (Do not substitute 7414 or  74LS14. They are TTL chips and operate on 4.5v to 5.5v and have low impedance inputs.)

 Simple Home Alarm Circuit Diagram

The 74C14 contains 6 Schmitt Trigger gates and 4 of these gates (Schmitt Inverters) are used in this schema.
The schema consists of a number of "building blocks" and the first consists of two transistors in a very clever "bootstrap" arrangement. The first transistor is turned on via the 3M3 and 47k. The second transistor is not turned on and the output is HIGH.

A small signal from the electret microphone will consist of positive and negative excursions and the negative excursion will turn the first transistor OFF. This will turn the second transistor ON and the left lead of the 100n will be pulled towards the 0v rail. The 100n is uncharged and the right lead will also be pulled towards the 0v rail and the input of the  74C14 will see a LOW. This will make the output HIGH and turn on the BC547 transistor.

When the second transistor turns ON, it also pulls the 2u2 down and this removes the "turn-on" voltage to the first transistor. The two transistors remain in this state for a few seconds while the 2u2 discharges and the voltage on the base of the first transistor rises. When this happens, the two transistors change state and the 2u2 charges. When the schema is waiting to detect audio, the 2u2 is charged via the 47k on the base of the first transistor and 47k collector resistor of the second transistor (plus the base-emitter voltage drop of the first transistor).

Simple Home Alarm Circuit Diagram A

 To exit the property, the EXIT button is pressed and this puts a HIGH on pin 1 of the IC so that any signal from the electret mic is not passed to the siren. The EXIT delay is determined by the value of the 100u and 2M2. Normally-open and normally-closed switches will also send a LOW to trigger the siren.

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Build A Voltage Inverter using IC NE 555

In many diagram we need to generate an internal adjustable voltage. This schema shows how it is possible to use a trusty old NE555 timer IC and a bit of external schemary to create a voltage inverter and doubler. The input voltage to be doubled is fed in at connector K1. To generate the stepped-up output at connector K2 the timer IC drives a two-stage inverting charge pump schema.

The NE555 is configured as an astable multivibrator and produces a rectangular wave at its output, with variable mark-space ratio and variable frequency. This results in timing capacitor C3 (see schema diagram) being alternately charged and discharged; the voltage at pin 2 (THR) of the NE555 swings between one-third of the supply voltage and two-thirds of the supply voltage.

Voltage Inverter Circuit Using IC NE555

The output of the NE555 is connected to two voltage inverters. The first inverter comprises C1, C2, D1 and D2. These components convert the rectangular wave signal into a nega-tive DC level at the upper pin of K2. The second inverter, comprising C4, C5, D3 and D4, is also driven from the output of IC1, but uses the negative output voltage present on diode D3 as its reference potential. The consequence is that at the lower pin of output connector K2 we obtain a negative volt-age double that on the upper pin.

Now let us look at the voltage feedback arrangement, which lets us adjust this doubled negative output voltage down to the level we want. The NE555 has a control voltage input on pin 5 (CV). Normally the voltage level on this pin is maintained at two-thirds of the supply voltage by internal schemary. The voltage provides a reference for one of the comparators inside the device. If the reference voltage on the CV pin is raised towards the supply voltage by an external schema, the timing capacitor C3 in the astable multivibrator will take longer to charge and to discharge. As a result the frequency of the rectangle wave output from IC1 will fall, and its mark-space ratio will also fall.

The source for the CV reference voltage in this schema is the base-emitter junction of PNP transistor T1. If the base volt-age of T1 is approximately 500 mV lower than its emitter voltage, T1 will start to conduct and thus pull the voltage on the CV pin towards the positive supply.

In the feedback path NPN transistor T2 has the function of a voltage level shifter, being wired in common-base configuration. The threshold is set by the resistance of the feedback chain comprising resistor R3 and potentiometer P1. When the emitter voltage of transistor T2 is more than approximately 500 mV lower than its base voltage it will start to conduct. Its collector then acts as a current sink. Potentiometer P1 can be used to adjust the sensitivity of the negative feedback schema and hence the final output voltage level.Using T1 as a voltage reference means that the schema will adjust itself to compensate not only for changes in load at K2, but also for changes in the input supply voltage. If K2 is disconnected from the load the desired output voltage will be maintained, with the oscillation frequency falling to around 150 Hz.

A particular feature of this schema is the somewhat unconventional way that the NE555’s discharge pin (pin 7) is connected to its output (pin 3). To understand how this trick works we need to inspect the innards of the IC. Both pins are outputs, driven by internal transistors with bases both connected (via separate base resistors) to the emitter of a further transistor. The collectors of the output transistors are thus isolated from one another [1].

The external wiring connecting pins 3 and 7 together means that the two transistors are operating in parallel: this roughly doubles the current that can be switched to ground.The two oscilloscope traces show how the output voltage behaves under different circumstances. The left-hand figure shows the behaviour of the schema with an input voltage of 9 V and a resistive load of 470 Ω connected to the lower pin of output connector K2. The figure on the right shows the situation with an input voltage of 10 V and a load of 1 kΩ on the lower pin of output connector K2. The pulse width and frequency of the rectangle wave at the output of IC1 are automatically adjusted to compensate for the differing conditions by the feedback mechanism built around T1 and T2.

Because of the voltage drops across the Darlington out-put stage in the IC (2.5 V maximum) and the four diodes (700 mV each) the schema achieves an efficiency at full load (470 Ω between the output and ground) of approximately 50 %; at lower loads (1 kΩ) the efficiency is about 65 %. Link

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Build a Efficient Negative Voltage Regulator Wiring diagram Schematic

How to Build a Efficient Negative Voltage Regulator Circuit Diagram. This simple Efficient Negative Voltage Regulator Circuit Diagram is One v;ay to provide good negative-voltage regulation is with a low-dropout positive-voltage regulator operating from a well-isolated secondary winding of switch-mode schema transformer. The technique works with any positive-voltage regulator, although highest efficiency occurs with low-dropout types. 

Under all loading conditions, the minimum voltage difference between the regulator ViN and VoUT pins must be at least 1.5 V, the LT1086`s low-dropout voltage. Efficient-negative-voltage-regulator Rating: 7.00/10 (23Votes cast)Category: Power Supply Circuits / AC to DC & DC to DCViews: 3Rank: 5One v;ay to provide good negative-voltage regulation is with a low-dropout positive-voltage regulator operating from a well-isolated secondary winding of switch-mode schema transformer. 

 Efficient Negative Voltage Regulator Circuit Diagram

The technique works with any positive-voltage regulator, although highest efficiency occurs with low-dropout types. Under all loading conditions, the minimum voltage difference between the regulator ViN and VoUT pins must be at least 1.5 V, the LT1086`s low-dropout voltage.Efficient-negative-voltage-regulatorIf this requirement isn`t met, the output falls out of regulation. 1vo programming resistors, R1 and R2, set the output voltage to 12 V, and the LT1086`s servo the voltage between the output and its adjusting (ADJ) terminals to 1.25 V. 

Capacitor C1 improves ripple rejection, and protection diode D1 eliminates common-load problems. Since a secondary winding is galvanically isolated, a regulator`s 12 V output can be referenced to ground. Therefore, in the case of a negative-voltage output, the positive-voltage terminal of the regulator connects to ground, and the -12 V output comes off the anode of Dl. The ViN terminal floats at 1.5 V or more above ground.

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Build a Funk Twang Guitar Effect Box Wiring diagram Schematic

How to Build a Funk (Twang) Guitar Effect Box Circuit Diagram. This is an audio effect schema that give extra oscillation to your guitar, percussive, or semi percussive instruments, you can call it a funk box. This  guitar effect schema is basically a damped oscillator that is set slightly below its critical oscillation point.  

The oscillator part is constructed by feeding back the output signal through a bandpass schema, with the center frequency is adjusted by potentiometer R7 to add an extra “twang” , adjustable from low to high pitched timbre. Potentiometer R4 is used to adjust the gain of the oscillator, should be set to damp the oscillation at the desired decay time.  

To adjust it, turn the knob slowly until a steady oscillation occurs, and turn back slightly just before it happens (the oscillation should ceases slowly). Here is the schematic diagram of the schema.

Funk (Twang) Guitar Effect Box Circuit Diagram

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Build a Photomultiplier Wiring diagram Schematic

How to Build a Photomultiplier Circuit Diagram? This Photomultiplier Circuit Diagram is typical of the way that a photomultiplier tube is used. The schema shown is ac coupled, but if dc coupling is needed, the capacitor can be omitted and a suitable interfacing method used. A typical tube is the widely available 931/931A.

Photomultiplier Circuit Diagram

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Build a Burglar Alarm With Timed Shutoff Wiring diagram Schematic

This is a very important schema for security. This is a simple Burglar Alarm With Timed Shutoff Circuit Diagram. When SI (sensor) is closed, power is applied to U2, a dual timer. After a time determined by C2, CI is energized after a predetermined time determined by the value of C5, pin 9 of U2 becomes low, switching off the transistor in the optoisolater, cutting anode current of SCR1 and DE-energizing Kl. The system is now reset. Notice that (i6x C2) is less than (R7xC$). The ON time is approximately given by:(R7xC5)-(R6xC2) = Ton

Burglar Alarm With Timed Shutoff Circuit Diagram

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