Circuit knowledge

Showing posts with label a. Show all posts

Showing posts with label a. Show all posts

Monday, January 26, 2015

Build a Peak Indicator

When when the condition of point is greater then how much + 4dB, changes for encouraged D1. Its handy around each one siphon with games console with good, around very last amplifiers and also in the alternative use, so that you can most people wanted. Together with the selling prices with outlet, a signify takes place by using concentrations previously + five dB (1. 25V rms). To get adapting to it within amounts of point, we will employ a more trim, in advance of capacitor C1.

Peak Indicator Circuit Diagram :

Parts:

R1 = 10K
R2 = 1.2K
R3 = 220K
R4 = 4.7K
R5 = 4.7K
C1 = 47uF-25V
C2 = 2.2uF-25V
Q1 = BC550C
Q2 = BC550C
D1 = Red LED

Notes:

It can be assembled on a general purpose PCB.
It can be powered from a 12V-15V regulated power supply.

Wednesday, October 15, 2014

Build a 25W Bridge Audio Amplifier with TDA2005

This is the 25W bridge audio amplifier built using single power IC TDA2005. Actually, the TDA2005 is a stereo power amplifier chip. It has two input channels and two output channel and delivers about 10W power output for each channel, since it connected in bridge mode then it will delivering up to 25W audio output. Take a note that the speaker terminals should not conected to the ground and mount the IC on the heatsink to prevent overheating.

25W Bridge Audio Amplifier with TDA2005 Circuit Diagram

Parts List:
R1 = 120K?
R2,5,6 = 1K?
R3,4 = 12?
R7,8= 1?
C1,5,7 = 220uF/25V
C2,10,11 = 100nF
C3,4 = 2.2uF/25V
C6,8 = 100uF/25V
C9 = 10uF/25V
IC1 = LM2005M / TDA2005

Build a 9V Wireless Microphone FM Transmitter

This FM transmitter circuit can be used as a wireless microphone, can be received by an ordinary 88- to 108-MHz FM broadcast receiver. For the power supply, this transmitter circuit is powered by a 9 V battery. To comply with the radiation limit of FCC rules, keep the antenna length under 12 inches. L1 is 6 turns of #24 wire wound around a pencil or a 1/4″ form, with turns spacing of 1 wire diameter. C6 is a gimmick capacitor which has value about 1 pF.

9V Wireless Microphone FM Transmitter Circuit Diagram

Sunday, October 5, 2014

LM1758 A Switching Regulator

The National Semiconductor LM 1578 A is a switching regulator which can easily be set up for such dc-to-dc voltage .conversion circuits as the buck, boost, and inverting configurations. The LM 1578 A features a unique comparator input stage which not only has separate pins for both the inverting and non-inverting inputs, but also provides an internal 1.0 V reference to each input, thereby simplifying circuit design and PC board layout. The output can switch upto 750 m A and has output pins for its collector and emitter to promote design flexibility. An external current limit terminal may be referenced to either the ground or the V_in terminal, depending upon the application.

Monday, September 8, 2014

Build a Power Supply Variable 1 3V 12 2V 1A Wiring diagram Schematic

Build a Power Supply Variable 1.3V - 12.2V 1A Circuit Diagram. In this schema R2 to set the output voltage. The maximum current is determined by R3, over-current protection schema inside the LM723 to detect the voltage on R3, if it reaches 0.65 V, the voltage output will be off her. So the current through R3 can not exceed 0.65 / R3 although output short-schema in his.

Power Supply Variable 1.3V - 12.2V 1A Circuit Diagram

Power

C3 and C4 are ceramic capacitors, as much as possible directly soldered to the PCB, this is because the LM723 is prone to oscillation that is not cool.

LM723 works with 9.5V input voltage to 40 V DC and the LM723 can generate its own current of 150mA when the output voltage is not more than 6-7V under input voltage.

Specifications:

Output (value estimated):

Vmin = (R4 + R5) / (R5 * 1.3)

Vmax = (7.15 / R5) * (R4 + R5)

Imax = 0.65/R3

Max. Power on R3: 0.42/R3

Min. DC Input Voltage (pin 12 to pin 7): Vmax + 5

Parts List:

B1 40V/2.5A

C1 2200uF (3300uF even better)

C2 4.7uF

C3 100nF

C4 1NF

C5 330nF

C6 100uF

Green LED D1

D2 1N4003

F1 0.2A F

F2 2A M

IC1 LM723 (in a DIL14 plastic package)

R1 1k

R2 Pot. 5k

R3 0.56R/2W

R4 3.3k

R5 4.7k

S1 250V/1A

T1 2N3055 on a heatsink 5K / W

TR1 220V/17V/1.5

Saturday, September 6, 2014

Converting a DCM Motor

We recently bought a train set made by a renowned company and just couldn’t resist looking inside the locomotive. Although it did have an electronic decoder, the DCM motor was already available 35 (!) years ago. It is most likely that this motor is used due to financial constraints, because Märklin (as you probably guessed) also has a modern 5-pole motor as part of its range. Incidentally, they have recently introduced a brushless model.

The DCM motor used in our locomotive is still an old-fashioned 3-pole series motor with an electromagnet to provide motive power. The new 5-pole motor has a permanent magnet. We therefore wondered if we couldn’t improve the driving characteristics if we powered the field winding separately, using a bridge rectifier and a 27 Ω current limiting resistor. This would effectively create a permanent magnet. The result was that the driving characteristics improved at lower speeds, but the initial acceleration remained the same. But a constant 0.5 A flows through the winding, which seems wasteful of the (limited) track power. A small schema can reduce this current to less than half, making this technique more acceptable.

Circuit diagram :

Converting a DCM Motor Circuit Diagram

The field winding has to be disconnected from the rest (3 wires). A freewheeling diode (D1, Schottky) is then connected across the whole winding. The centre tap of the winding is no longer used. When FET T1 turns on, the current through the winding increases from zero until it reaches about 0.5 A. At this current the voltage drop across R4-R7 becomes greater than the reference voltage across D2 and the opamp will turn off the FET. The current through the winding continues flowing via D1, gradually reducing in strength. When the current has fallen about 10% (due to hysteresis caused by R3), IC1 will turn on T1 again. The cur-rent will increase again to 0.5 A and the FET is turned off again. This goes on continuously.

The current through the field winding is fairly constant, creating a good imitation of a permanent magnet. The nice thing about this schema is that the total current consumption is only about 0.2 A, whereas the current flow through the winding is a continuous 0.5 A.

We made this modification because we wanted to convert the locomotive for use with a DCC decoder. A new controller is needed in any case, because the polarity on the rotor winding has to be reversed to change its direction of rotation. In the original motor this was done by using the other half of the winding.

There is also a good non-electrical alter-native: put a permanent magnet in the motor. But we didn’t have a suitable magnet, whereas all electronic parts could be picked straight from the spares box.

Source By : Streampowers

Friday, September 5, 2014

How a Power Supply Works

This article describes in easy terms the operation of a Basic Power Supply unit of the kind used with telecommunications instrumentality (switchboards, physics house exchange systems, plan-sets, etc).

The term power provide is a lot of normally abbreviated to PSU, this may be wont to electronic device to be ready to work. So, the facility supply unit is use to come up with a voltage that may be supply in associate device in accordance with the wants of the mains voltage from that device. Telecommunications instrumentality and notebook is meant to control on lower voltages than electrics domestic Mains voltage. So as to scale back this voltage a PSU (Power Supply Unit) is employed.

To provide a useable low voltage the PSU desires a number of criteria :

Scale back the Mains 220V AC (Alternating current) voltage to a lower level, examples 5VDC.
Convert this Lower Voltage from AC to DC (Direct current), this use Diode and Capacitor to converting.
Regulate the DC output to make amends for varied load (current demand)
Give Protection against excessive input/output voltages, it use Regulator supply system.

1. Reduction of AC Mains

This is achieved by employing a device called a electrical device associate magnetic attraction device consisting of associate ferric email iron core that incorporates a sizable amount of turns of wire wound around it, called the first Winding. The ends of those turns of wire being connected to the input voltage, in this case Mains AC.

A second range of turns of wire-protected measure wound round the coil, this set being called the coil.

The distinction between the quantity of turns provides simplest way of reducing a high AC voltage to a lower one.

2. Conversion of AC to DC

To convert our currently low AC voltage to DC we tend to use a Rectifier Diode connected to the coil.

This is a chemical element diode, that has operation analogous to a bicycle tyre valve (as the valve solely permits air to flow into the tyre, the diode solely permits current to flow in one direction).

As our low AC voltage are going to be functioning at a frequency of 50 - 60Hz (Mains AC frequency) its fascinating to scale back the inherent hum on this to a lower level.

This is achieved by a method called Smoothing (filtering out the bumps within the AC).

A simple thanks to scale back the hum is to use Full Wave Rectification.

Today this is often typically done by four diodes during a bridge configuration called a Bridge Rectifier. (This will be four individual diodes or an infatuated self contained package)

3. Give Regulation of Outp ut Voltage, [SEE next article from about REGULATOR.

The capacitance could be a device capable of storing energy the quantity of energy and therefore the time it remains hold on counting on the worth. In a straightforward PSU the simplest thanks to give regulation to make amends for varied load conditions is to use a try of comparatively high price Electrolytic Capacitors.

Their values during this case being within the between of 470uF to 4700uF counting on the applying and therefore the quantity of current needed from the output of the unit. One of these capacitors and Electrolyte Capacitors is connected across the DC output of the rectifier diode(s) or bridge, this electrical device conjointly providing an additional degree of smoothing the output wave.

The second electrical device is connected via an occasional price, medium to high electric power resistance, that assists in limiting this demand.

4. Protection against excessive voltages

In a straightforward PSU the simplest thanks to do that is by providing fuses at the input to the electrical device, usually within the live facet of the mains provide, conjointly at the DC outputs.
In the event of associate excessive input voltage, or excessive current being drawn from the output, one amongst these fuses ought to commonly blow protective the PSU and therefore the instrumentality connected to that.
The electrical device might also be fitted with an indoor or external thermal fuse, which can open if the electrical device becomes hot thanks to the said conditions.

Power

How a Power Supply Works

Thursday, September 4, 2014

Constructing a Universal Power Supply using LM317 Rise

This is a basic, Universal Power Supply voltage regulator schema using an LM317, 3-terminal regulator in a TO-220package. The Universal Power Supply output voltage can be set to anywhere in the range one.5V to 30V by selecting resistances. By using a potentiometer, R2, as of the resistors you can dial up the output voltage wanted. Either AC or DC input can be supplied to the PCB by a socket or terminal block. Connection can be either way around. This is because they have provided a bridge rectifier on board. The input DC voltage to the regulator must be at least two.5V above the necessary output voltage. An off/on switch is provided.

For lots of applications (say 12V at 60mA) a heat sink wont be required. The LM317 will provide slightly higher output voltages than 30 volts. However, for most hobbyists over 30V wont be needed. So to make a small PCB they have used some electrolytic capacitors rated to 35 volts. To be safe for continuous operation the maximum input DC voltage to the regulator ought to not be over 33V. With a two.5V to three.0V drop across the regulator this will give a regulated output of 30V. You can draw up to one.5A from the LM317. In case you need higher then use an LM338T rated to 5A.

When outside capacitors are used with any IC regulator it is lovely practice to add protection diodes to prevent the capacitors discharging back in to the regulator in the event of abnormal operating conditions, like a sudden short schema on the input or the output, or a back emf from an inductive load. That is the function of D one and D Two.

The worth of R1 can range anywhere from 120R to 1200R However, diagram from most other sources settle on using either 220R or 250R. They have used 240R or 250R. The voltage drop across R1is one.25V for all values, and this is the key to the design. one.25V is the reference voltage of the regulator. Whatever current flows through R1 also flows through R2, and the sum of the voltage drops across R1 and R2 is the output voltage. (Additional current Id also flows in R2 but it is usually 50uA so is negligible.)

The design formula are:

VOUT = 1.25 (1 + R2/R1) volts, or alternatively

R2/R1 = (VOUT/1.25) - 1

So in case you know VOUT & R1 is 250R then you can calculate R2. In case you find that the 5K potentiometer used forR2 does not give you the degree of fine control over the voltage output range that you need then you can use these formula to fine-tune R1 & R2 to better suited values.

Universal Power Supply Schematic Diagram

Wednesday, September 3, 2014

Simple Toss A Coin Binary Box Wiring diagram Schematic

This is a Simple Toss A Coin Binary Box Circuit Diagram. The entropy of such a process is given by the binary entropy function. This Circuit uses an astable multivibrator to vary the heads-or-tails condition, and a flip-flop to store the condition given by the multivibrator Consequently, the schema is wired so that the flip-flop`s state is changed once for each full cycle the multivibrator goes through to assure an absolutely even 50-50 chance of a heads or tails loss.

Simple Toss A Coin Binary Box Circuit Diagram

Simple

Wednesday, August 27, 2014

Build a Power Saving Intermittent Converter Wiring diagram Schematic

Build a Power Saving Intermittent Converter Circuit Diagram. This Power-Saving Intermittent Converter Circuit Diagram switches its dc/dc converter, IC1, off whenever the large filter capacitor, C6, has sufficient charge to power the load. This particular schema uses a dc/dc converter that produces 115 Vdc from, a 9-Vdc input; you can tailor the schema to suit other converters. The heart of the schema is a 555 timer configured as a dual-limit comparator. Thus, the 555 turns the converter on or off, depending on the voltage across C6.

The 555`s complementary output lights the charge LED when the FET is on. Initially, the voltage on C6 is zero, and the 555`s output turns on the FET, Ql, in turn, enabling the converter to run, which charges C6. When the voltage on the capacitor reaches the value set by R3, the 555 turns the converter off. Then, C6 slowly discharges into the combined load of the voltage divider (R2, R3, and R4) and the reverse-biased blocking diode, Dl. When the voltage falls below 1/3 Vcc, the 555 restarts the dc/dc converter.

If this schema powers a load that periodically goes into a zero-power, shutdown mode, the 555 switches the dc/dc converter on full time whenever the load kicks in. When the supply voltage falls below 7.5 V, the output of the converter is no longer high enough to charge, the LED doesn`t light. The schema uses 205 mA when the converter is on and 10 mA when the converter is off. The duty cycle comprises a 5-s on period, a 150-s off period, and it represents a 92% power reduction. You can further reduce power consumption by removing the charge LED and using a CMOS 555 and a CMOS 78L05 regulator.

Power-Saving Intermittent Converter Circuit Diagram

Power-Saving

Power-Saving Intermittent Converter Circuit Diagram

Thursday, August 21, 2014

Build a Converter VGA to BNC Adapter

There are monitors which only have three BNC inputs and which use composite synchronization (‘sync on green’). This schema has been designed with these types of monitor in mind. As can be seen, the schema has been kept very simple, but it still gives a reasonable performance. The principle of operation is very straightforward. The RGB signals from the VGA connector are fed to three BNC connectors via AC-coupling capacitors. These have been added to stop any direct current from entering the VGA card. A pull-up resistor on the green output provides a DC offset, while a transistor (a BS170 MOSFET) can switch this output to ground. It is possible to get synchronisation problems when the display is extremely bright, with a maximum green component.

In this case the value of R2 should be reduced a little, but this has the side effect that the brightness noticeably decreases and the load on the graphics card increases. To keep the colour balance the same, the resistors for the other two colors (R1 en R3) have to be changed to the same value as R2. An EXOR gate from IC1 (74HC86) combines the separate V-sync and H-sync signals into a composite sync signal. Since the sync in DOS-modes is often inverted compared to the modes commonly used by Windows, the output of IC1a is inverted by IC1b. JP1 can then by used to select the correct operating mode. This jumper can be replaced by a small two-way switch, if required.

VGA to BNC adapter PCB layout

http://streampowers.blogspot.com/2012/11/build-converter-vga-to-bnc-adapter.html

This switch should be mounted directly onto the PCB, as any connecting wires will cause a lot of interference. The PCB has been kept as compact as possible, so the schema can be mounted in a small metal (earthed!) enclosure. With a monitor connected the current consumption will be in the region of 30 mA. A 78L05 voltage regulator provides a stable 5 V, making it possible to use any type of mains adapter, as long as it supplies at least 9 V. Diode D2 provides protection against a reverse polarity. LED D1 indicates when the supply is present. The schema should be powered up before connecting it to an active VGA output, as otherwise the sync signals will feed the schema via the internal protection diodes of IC1, which can be noticed by a dimly lit LED. This is something best avoided.

Resistors:

R1,R2,R3 = 470Ω

R4 = 100Ω

R5 = 3kΩ3

Capacitors:

C1,C3,C5 = 47µF 25V radial

C2,C4,C6,C7,C10 = 100nF ceramic

C8 = 4µF7 63V radial

C9 = 100µF 25V radial

Semiconductors:

D1 = LED, high-efficiency

D2 = 1N4002

T1 = BS170
IC1 = 74HC86
IC2 = 78L05

Miscellaneous:
JP1 = 3-way pinheader with jumper
K1 = 15-way VGA socket (female), PCB mount (angled pins)
K2,K3,K4 = BNC socket (female), PCB mount, 75Ω

Wednesday, August 20, 2014

Build a Regulated Charge Pump Wiring diagram Schematic

How to Build a Regulated Charge Pump Circuit Diagram. The dc-dc converter substitutes a voltage triplet in place of the external inductor and the diode that`s typically associated with the switching regulator, IC1. Inverting and non inverting amplifiers in the MOS-FET-driver (IC2) activate a diode-capacitor tripling network (D1 through D3, CI through C3).

A 50-kHz oscillator residing within IC1 produces the EXT signal (pin 6), IC2 converts this signal into drive signals (180Â° out of phase) for the tripler. The resulting charge-discharge action in the capacitors recharges C3 toward 10 V every 20 The ferrite bead limits output ripple to about 20-mVpp for a 50-mA load. Conversion efficiency is about 70% for the 5-V input, 10-V output configuration.

Regulated Charge Pump Circuit Diagram

Regulated

Build a Triac 0 Point Switch Wiring diagram Schematic

How to Build a Triac 0 Point Switch Circuit Diagram. The point where the line voltage is 0 V is the Zero CrossOn the initial part of the positive half cycle, the voltage is changing rapidly from zero causing a large current to flow into capacitor C2. The current through C2 flows through R4, D3, and D4 into the gate of the TRIAC Q2 causing it to turn on very close to zero voltage. Once Q2 turns on, capacitor C3 charges to the peak of the line voltage through D5.

Triac 0 Point Switch Circuit Diagram

Triac

When the line voltage passes through the peak, D5 becomes reverse-biased and C3 begins to discharge through D4 and the gate of Q2. At this time the voltage on C3 lags the line voltage. When the line voltage goes through zero there is still some charge on C3 so that when the line voltage starts negative C3 is still discharging into the gate of Q2.

Thus Q2 is also turned on near zero on the negative half cycle. This operation continues for each cycle until switch SI is closed, at which time SCR Ql is turned on. Ql shunts the gate current away from Q2 during each positive half cycle keeping Q2 from turning on. Q2 cannot turn on during the negative cycle because C3 cannot charge unless Q2 is on during the positive half cycle.

Saturday, August 16, 2014

Constructing a Universal Power Supply using LM317 Rise

This is a basic, Universal Power Supply voltage regulator schema using an LM317, 3-terminal regulator in a TO-220package. The Universal Power Supply output voltage can be set to anywhere in the range one.5V to 30V by selecting resistances. By using a potentiometer, R2, as of the resistors you can dial up the output voltage wanted. Either AC or DC input can be supplied to the PCB by a socket or terminal block. Connection can be either way around. This is because they have provided a bridge rectifier on board. The input DC voltage to the regulator must be at least two.5V above the necessary output voltage. An off/on switch is provided.

For lots of applications (say 12V at 60mA) a heat sink wont be required. The LM317 will provide slightly higher output voltages than 30 volts. However, for most hobbyists over 30V wont be needed. So to make a small PCB they have used some electrolytic capacitors rated to 35 volts. To be safe for continuous operation the maximum input DC voltage to the regulator ought to not be over 33V. With a two.5V to three.0V drop across the regulator this will give a regulated output of 30V. You can draw up to one.5A from the LM317. In case you need higher then use an LM338T rated to 5A.

When outside capacitors are used with any IC regulator it is lovely practice to add protection diodes to prevent the capacitors discharging back in to the regulator in the event of abnormal operating conditions, like a sudden short schema on the input or the output, or a back emf from an inductive load. That is the function of D one and D Two.

The worth of R1 can range anywhere from 120R to 1200R However, diagram from most other sources settle on using either 220R or 250R. They have used 240R or 250R. The voltage drop across R1is one.25V for all values, and this is the key to the design. one.25V is the reference voltage of the regulator. Whatever current flows through R1 also flows through R2, and the sum of the voltage drops across R1 and R2 is the output voltage. (Additional current Id also flows in R2 but it is usually 50uA so is negligible.)

The design formula are:

VOUT = 1.25 (1 + R2/R1) volts, or alternatively

R2/R1 = (VOUT/1.25) - 1

So in case you know VOUT & R1 is 250R then you can calculate R2. In case you find that the 5K potentiometer used forR2 does not give you the degree of fine control over the voltage output range that you need then you can use these formula to fine-tune R1 & R2 to better suited values.

Universal Power Supply Schematic Diagram

Wednesday, August 13, 2014

Build a Isolated Dc Dc Converter Wiring diagram Schematic

This Isolated Dc-Dc Converter Circuit Diagram, a TU31 shunt regulator is used to sense the output voltage. The TU31 drives the LED of a 4N28 optocoupler which provides feedback to the MAX641 while maintaining isolation between the input, +12 V, andJhe output, +15 V. ln this Isolated Dc-Dc Converter Circuit Diagram, the +15 V output is fully regulated with respect to both line and load changes.

Isolated Dc-Dc Converter Circuit Diagram

Isolated Dc-Dc Converter Circuit Diagram

Build a Universal Active Filter Wiring diagram Schematic

The Universal Active Filter Circuit Diagram as shown gives the bandpass operation the transfer function calculated from FBP(s) = where = 1 + s/Qo>0 + s2/w02. The cut-off frequency, 0, and the Q-factor are given by 0 = g/C and Q = gR/2 where g is the trans conductance at room temperature. Interchanging the capacitor C with the resistor R at the input of the schema high-pass operation is obtained. A low-pass filter is obtained by applying two parallel connections ctf R and C as shown in Fig. 2. The low-pass operation may be much improved with the schema as given in Fig. 3. Here the gain and Q may be set up separately with respect to the cut-off frequency according to the equations Q = 1/fB = 1 + R2/R!, A = Q2 and 0 = g ffi/C.

Build a Universal Active Filter Circuit Diagram

Subscribe to: Posts (Atom)

visit counter for blogspot