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Saturday, August 31, 2013

 Power On Time Delay Relay Circuit

Description 
Below is a thermostat circuit I recently built to control a 1300 watt space heater. The heater element (not shown) is connected in series with two back to back 16 amp SCRs (not shown) which are controlled with a small pulse transformer. The pulse transformer has 3 identical windings, two of which are used to supply trigger pulses to the SCRs, and the third winding is connected to a PNP transistor pair that alternately supply pulses to the transformer at the beginning of each AC half cycle. The trigger pulses are applied to both SCRs near the beginning of each AC half cycle but only one conducts depending on the AC polarity.
DC power for the circuit is shown in the lower left section of the drawing and uses a 1.25uF, 400 volt non-polarized capacitor to obtain about 50mA of current from the AC line. The current is rectified by 2 diodes and used to charge a couple larger low voltage capacitors (3300uF) which provide about 6 volts DC for the circuit. The DC voltage is regulated by the 6.2 volt zener and the 150 ohm resistor in series with the line limits the surge current when power is first applied.
The lower comparator (output at pin 13) serves as a zero crossing detector and produces a 60 Hz square wave in phase with the AC line. The phase is shifted slightly by the 0.33 uF, 220K and 1K network so that the SCR trigger pulse arrives when the line voltage is a few volts above or below zero. The SCRs will not trigger at exactly zero since there will be no voltage to maintain conduction.
The upper two comparators operate in same manner as described in the "Electronic thermostat and relay" circuit. A low level at pin 2 is produced when the temperature is above the desired level and inhibits the square wave at pin 13 and prevents triggering of the SCRs. When the temperature drops below the desired level, pin 2 will move to an open circuit condition allowing the square wave at pin 13 to trigger the SCRs.
The comparator near the center of the drawing (pins 8,9,14) is used to allow the heater to be manually run for a few minutes and automatically shut off. A momentary toggle switch (shown connected to a 51 ohm resistor) is used to discharge the 1000uF capacitor so that pin 2 of the upper comparator moves to a open circuit state allowing the 60 Hz square wave to trigger the SCRs and power the heater. When the capacitor reaches about 4 volts the circuit returns to normal operation where the thermistor controls the operation. The momentary switch can also be toggled so that the capacitor charges above 4 volts and shuts off the heater if the temperature is above the setting of the pot. 
Circuit Diagram 
Source http://www.bowdenshobbycircuits.info/page2.htm#delay.gif
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Friday, August 16, 2013

Audio Rejection filter Circuit

This narrow band filter using the 741 operational amplifier can provide up to 60 dB of rejection. With resistors equal to 100 K and capacitors equal to 320 pF, the circuit will reject 50 Hz. Frequencies within the range 1 Hz to 10 kHz may be rejected by selecting components in accordance with the formula. To obtain rejections better than 40 dB, resistors should be matched to 0% and capacitors to 1%.

 Audio Rejection filter Circuit Diagram

Audio Rejection filter Circuit

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Thursday, August 15, 2013

FTDI Bitbang IR Remote Transmitter Receiver

I use my computer every single minute, I do my work at home and I need to finish lots of paperwork. My computer helps me in almost everything I do. I make sure that my pc is able to do multitasking and functioning well. Just like our body, it should be fit to do all the workload that must be finished within the day.

FTDI Bitbang IR Remote
To come up with another task that a pc can add to its functions, an IR remote was created through an FTDI that receives and transmits data other than the Universal Serial Bus. This is definitely a big help that my pc can easily cope up with simultaneously.

FTDI Bitbang IR Remote
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Wednesday, August 14, 2013

Roper 2079b00 Wiring Diagram

Roper 2079b00 Wiring Diagram
(click for full size image)


The Part of Roper 2079b00 Wiring Diagram:black wire, neutral grounded, ind lite, relay coil, clock, bake eleh, door latch, red wire,

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Tuesday, August 13, 2013

Pioneer Receiver Amplifier Cable Harness Schematic

Pioneer Wiring Diagram on Pioneer Bdp 320 To Av Receiver Or Amplifier Cable Harness Schematic
Pioneer Bdp 320 To Av Receiver Or Amplifier Cable Harness Schematic.


Pioneer Wiring Diagram on Need Pioneer Deh P3100ub Wiring Diagram   Fixya
Need Pioneer Deh P3100ub Wiring Diagram Fixya.


Pioneer Wiring Diagram on For A Pioneer Mosfet 50wx4 Need A Wiring Diagram   Or   Justanswer
For A Pioneer Mosfet 50wx4 Need A Wiring Diagram Or Justanswer.


Pioneer Wiring Diagram on Pioneer Wire Harness Deh P2500 15 17 1900 P4500mp Pr3   Ebay
Pioneer Wire Harness Deh P2500 15 17 1900 P4500mp Pr3 Ebay.


Pioneer Wiring Diagram on 1985 1994 2bnissan 2bradio 2bwiring 2bdiagram Jpg
1985 1994 2bnissan 2bradio 2bwiring 2bdiagram Jpg.


Pioneer Wiring Diagram on Pioneer Deh P6400 Wiring Diagram   Group Picture  Image By Tag
Pioneer Deh P6400 Wiring Diagram Group Picture Image By Tag.


Pioneer Wiring Diagram on Need Wiring Diagram For Model Pioneer Deh 63ub   Fixya
Need Wiring Diagram For Model Pioneer Deh 63ub Fixya.


Pioneer Wiring Diagram on Wiring Diagram
Wiring Diagram.


Pioneer Wiring Diagram on Need A Wiring Diagram For Pioneer Wma Mp3 Super   Fixya
Need A Wiring Diagram For Pioneer Wma Mp3 Super Fixya.


Pioneer Wiring Diagram on 1550 Like Manual And Other Informations  For Example  Wiring Diagram
1550 Like Manual And Other Informations For Example Wiring Diagram.


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Monday, August 12, 2013

Bass Booster Circuit

Increase the bass output of your present instrument at modest cost!
Bass Boost is todays sound... whether its the driving, gut-vibration pulsation of disco, or the solid bass line of soft, hard, or laid-back rock. One way to get the modern bass-boost sound without running out and buying an all-new expensive piece of equipment is to use a Bass Booster between your guitar, electronic organ or what-have-you, and the instrument amplifier. 

A bass booster strips the highs from the instruments output signal and amplifies low frequencies, feeding on "all-bass" sound to the instrument amplifier. Naturally, the bigger the speaker used with the amp, the more powerful the bass: use 15-inchers with the Bass Booster and you can rattle the windows. Bass Booster is powered by an ordinary 9 volt transistor radio battery. It can be assembled on a small printed board or on a veroboard using point to point wiring. The booster connects between your instrument and its amplifier through two standard RCA Jacks.

Circuit Diagram:
Bass Booster Circuit Bass Booster Circuit Diagram
Parts:
P1 = 50K
P2 = 100K
R1 = 22K
R2 = 470K
R3 = 47K
R4 = 10K
R5 = 470R
R6 = 1K
Q1 = 2N2222
C1 = 2.2uF-25v
C2 = 100nF-63v
C31 = 00nF-63V
C4 = 3.3uF-25v
C5 = 470uF-25v
D1 = 5mm. Red Led
Q1 = 2N2222
B1 = 9v Battery
J1 = RCA Audio Input Socket
J2 = RCA Audio Output Socket
S1 = On-Off Switch

Using Bass Booster:
Connect your electronic guitar or other electronic instrument to input jack J1; Connect output jack J2 to your instruments amplifiers normally-used input. With power switch S1 off, key S2 so the instrument feeds directly to the instrument amplifier. With P2 set full counter-clockwise (Off), turn power switch S1 on, key S2 once, and advance P2 for the desired Bass Boost level. To cut back to natural sound just stomp down on S2 and key the Bass Booster out. Dont worry about leaving power switch S1 on for several hours of a gig. The circuit pulls less than 1mA from the battery, so battery will last many, many months.
 
 
Streampowers
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Sunday, August 11, 2013

Little Door Guard

If some intruder tries to open the door of your house, this circuit sounds an alarm to alert you against the attempted intrusion. The circuit (Fig. 1) uses readily available, low-cost components. For compactness, an alkaline 12V battery is used for powering the unit. Input DC supply is further regulated to a steady DC voltage of 5V by 3-pin regulator IC 7805 (IC2).


Circuit of the door guard
Fig. 1: Circuit of the door guard

Assemble the unit on a general-purpose PCB as shown in Fig. 4 and mount the same on the door as shown in Fig. 3. Now mount a piece of mirror on the door frame such that it is exactly aligned with the unit. Pin configurations of IC UM3561 and transistors 2N5777 and BC547 are shown in Fig. 2. 

UM3561 and transistors
Fig. 2: Pin configurations of UM3561 and transistors 2N5777 and BC547

Initially, when the door is closed, the infrared (IR) beam transmitted by IR LED1 is reflected (by the mirror) back to phototransistor 2N5777 (T1). The IR beam falling on phototransistor T1 reverse biases npn transistor T2 and IC1 does not get positive supply at its pin 5. As a result, no tone is produced at its output pin 3 and the loudspeaker remains silent. Resistor R1 limits the operating current for the IR LED.
When the door isopened, the absence of IR rays at phototransistor T1 forward biases npn transistor T2, which provides supply to  positiveIC1. Now 3-sirensound generator IC UM3561 (IC1) gets power via resistor R5. The output of IC1 at pin 3 is amplified by Darlington-pair transistors T3 and T4 to produce the alert tone via the loudspeaker. 

Back view of the door assembly
Fig. 3: Back view of the door assembly

Rotary switch S2 is used to select the three preprogrammed tones of IC1. IC1 produces fire engine, police and ambulance siren sounds when its pin 6 is connected to point F, P or A, respectively.

Suggested enclosure
Fig. 4: Suggested enclosure with major components layout
 
 
 
http://streampowers.blogspot.com/2012/07/little-door-guard.html 
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Saturday, August 10, 2013

Amplifier Timer Circuit Diagram

Amplifier Timer Circuit Diagram
This
circuit turns-off an amplifier or any other device when a low level
audio signal fed to its input is absent for 15 minutes at least. Pushing
P1 the device is switched-on feeding any appliance connected to SK1.
Input audio signal is boosted and squared by IC2A & IC2B and
monitored by LED D4.

When D4 illuminates, albeit for any fairly
short peak, IC3 is reset and restarts its counting. Pin 2 of IC3 is
still at the low state, the two transistors seem like on too as the
relay operates. When, after a 15 minutes delay, no signal appeared at
the input, IC3 ends its counting and pin 2 will go high. Q1 & Q2
stop conducting too as the relay switches-off. The device is thus
totally off too seem like the appliances connected to SK1. C5 & R9
reset IC3 at power-on. P2 allows switch-off at any moment.
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Friday, August 9, 2013

Mains Remote Control Decoder

This receiver/decoder forms part of a simple mains network remote control system, which also includes the ‘Mains Remote Transmitter’ and the ‘Mains Remote Encoder’. The decoder is built around IC1, which is a Holtek type HT12D or HT12F. For the receiver we use the same circuit as in the ‘mains remote switch’, namely a passive circuit tuned to approximately 143 kHz, since we assume that the transmitter is powerful enough to provide an adequate signal. Two 4069U inverters (IC2) are used to convert the received signal to TTL levels. D1 and D2 provide extra protection against noise pulses and the like. The sensitivity can be adjusted using P3, but you should bear in mind that over-driving IC2 can cause corruption of the data.

Mains Remote Control Decoder circuit diagram schematic projectThe trick with IC2 is that a small offset applied to the first buffer causes the second buffer to be displaced from the middle (which can be checked using a multimeter), so that the following monostable multi-vibrator (IC3, a 4538) receives a usable burst as a trigger signal. IC3a is re-triggerable, which means that if a trigger pulse arrives within the set time, the output pulse is extended. However, if the set pulse width is too long, the output pulses are extended so much that the decoder will not recognize them as valid data.

Mains Remote Control Decoder circuit diagram schematic projectIC3a thus recovers the originally sent code. P2 is added to the circuit to allow the pulse length to be adjusted as accurately as possible, but an oscilloscope is required for this. In practice, the adjustment is not all that critical and P2 can be simply set to its mid-range position. The output of IC3a is fed to the decoder (IC1), which compares the recovered code with the settings of S1 and S2. If the received code matches these settings, output VT goes High and some sort of application can be energized via buffer T2. If you have in mind connecting an active buzzer to the buffer output, you must thoroughly decouple it using a 10-mH coil in series and a 100-µF/16-V electrolytic capacitor in parallel, since these buzzers can be a source of stubborn interference.

Mains Remote Control Decoder circuit diagram schematic projectThe second monostable (IC3b) is used to generate a supplementary pulse with a duration of roughly one second. The pulse length can be modified (by changing R2 and/or C2) to meet the needs of a particular application that requires a certain minimum duration. T1 acts as a simple buffer for this output. As already noted, in principle two different types of decoder can be used: HT12D or HT12F. The HT12D has four data-bit outputs (AD8–AD11), with the data being made available on the SIL header K1. In this case it is better not to fit S2. If an HT12F is used for the decoder, K1 has no function, but a 12bit address can be set.

Mains Remote Control Decoder circuit diagram schematic projectNaturally, the oscillator of the decoder should be tuned to match the encoder used with the transmitter. For the HT12D/F, the oscillator frequency is 50 times that of the encoder. That means that here the oscillator must be set to around 112 kHz. According to the related curve on the data sheet, this requires an external resistance of approximately 115 kΩ to be connected between the OSC1 and OSC2 pins. This can be precisely set using P1, and the potentiometer also allows for adjustments to compensate for various tolerances.

The power supply for the circuit is designed according to the usual standard configuration, with the transformer (Tr2) being intentionally somewhat over-dimensioned to provide extra capacity for powering small applications (buzzer, LED etc.). Building the circuit is a simple task if the illustrated printed circuit board is used. Since the power supply (including the transformer) is fitted on the circuit board, the amount of wiring required is minimal.

Resistors:
  • R1 = 100kΩ
  • R2 = 47kΩ
  • R3 = 1MΩ
  • R4 = 330kΩ
  • R5 = 10MΩ
  • P1 = 25kΩ preset
  • P2 = 100kΩ preset
  • P3 = 50kΩ preset
Capacitors:
  • C1 = 100pF
  • C2 = 1µF MKT, lead pitch 5mm or 7.5mm
  • C3 = 22nF 275VAC, Class X2
  • C4 = 22 n ceramic, lead pitch 5mm
  • C5,C7 = 220pF
  • C6 = 2nF2 ceramic, lead pitch 5mm
  • C8,C9,C10 = 100nF
  • C11 = 100nF ceramic, lead pitch 5mm
  • C12 = 10µF 63V radial
  • C13 = 470µF 25V radial
  • C14-C17 = 47nF ceramic, lead pitch 5mm
Inductor:
  • L1 = 470µH miniature choke
Semiconductors:
  • D1,D2 = BAT85
  • T1,T2 = BC547
  • IC1 = HT12D/F (Holtek) (Farnell) *
  • IC2 = 4069U
  • IC3 = 4538
  • IC4 = 7812
Miscellaneous:
  • K1 = 4-way pinheader
  • K2 = 2-way PCB terminal block, lead pitch 7.5mm
  • S1 = 8-wayDIP-switch
  • S2 = 4-way DIP-switch *
  • B1 = B80C1500 (rectangular) (80V piv, 1.5A)
  • TR1 = N30 ring core 16x6.3 mm EPCOS B64290L45X830 (Farnell) *
  • TR2 = mains transformer 15V/1.5VA, short circuit resistant, e.g., Block type VB 1,5/1/ 15
  • * see text
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Thursday, August 8, 2013

Versatile Micropower Battery Protector

Protect your expensive batteries from discharge damage with this mini-sized electronic cutout switch. It uses virtually no power and can be built to suit a wide range of battery voltages.
Main Features
  • Disconnects load at preset battery voltage
  • Automatically reconnects load when battery recharged
  • Ultra-low power consumption (<20ma)
  • Miniature size
  • 10A maximum rating
  • Suitable for use with 4.8-12.5V batteries
  • Transient voltage protection (optional)
Suitable for use in...
  • Cars, boats & caravans
  • Security systems
  • Emergency lighting
  • Small solar installations
  • Camera battery packs
  • Many other low-power applications
Picture of the project:
versatile-micropower-battery-protector-circuit1
versatile-micropower-battery-protector-circuit-backside 2

Back in May 2002, we (Silicon Chip) presented the "Battery Guardian", a project designed specifically for protecting 12V car batteries from over-discharge. This unit has proven to be very popular and is still available from kit suppliers. This new design does not supersede the Battery Guardian – at least not when it comes to 12V car batteries. Instead, it’s a more flexible alternative that can be used with a wide range of battery voltages.

Parts layout:
front-parts-layout-versatile-micropower-battery-protector-circuit 3
back-parts-layout-versatile-micropower-battery-protector-circuit 4

In this new "Micropower Battery Protector", we’ve dispensed with the low-battery warning circuitry and the relatively cheap N-channel MOSFET used in the Battery Guardian in favour of a physically smaller module that steals much less battery power. It costs a little more but can switch lower voltages, allowing it to be used with 6V & 12V lead-acid batteries and 4-cell to 10-cell NiCd and NiMH battery packs.

PCB layout:
pcb-layout-versatile-micropower-battery-protector-circuit 5

Most battery-powered equipment provides no mechanism for disconnecting the batteries when they’re exhausted. Even when the voltage drops too low for normal operation, battery drain usually continues until all available energy is expended. This is particularly true of equipment designed to be powered from alkaline or carbon cells but retro-fitted with rechargeables.

Circuit diagram:
versatile-micropower-battery-protector-circuit-diagram 6

Another example is emergency lighting and security equipment designed to be float-charged from the mains. In an extended blackout period, the batteries can be completely drained and may not recover when the mains power is finally restored.
Source: Silicon Chip 27 July 2004
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Wednesday, August 7, 2013

Voice Scrambler

With this circuit you can modify how your voice sounds by changing the pitch of your voice. This circuit can be connected to a phone and with a duplicate circuit on the end of the phone line, you can have a scrambled voice communication. The way the circuit works is as follows: If we cut the circuit in half at the T2 transformer and include the LM324 on the left side, you will see that the LM324 portion of the circuit is a tone oscillator which shifts the frequency of all input signals to a new higher frequency. When the voice and the tone oscillator mix frequencies the voice is not recognized. The voice signal is then inputted to the second stage which again shifts the voice signal again. I recommend that the first stage be tuned to a frequency that is 100hz lower then the second stage.

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Tuesday, August 6, 2013

Two Led Pilot Light


This circuit is designed on request and can be useful to those whishing to have, say, a red LED illuminated when an appliance is on and a green LED illuminated when the same appliance is off. Any mains operated appliance can be monitored by this circuit provided a suitable mains switch, capable of withstanding the full load current, is used for SW1.When SW1 is closed, the load and D4 are energized, Q1 is saturated and shorts D3, thus preventing its illumination.
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Monday, August 5, 2013

Build a Scanner Voice Squelch Circuit Diagram

This Scanner Voice Squelch Circuit Diagram detects the presence of audio (voice) on the output of a scanner. If the scanner stops on a `dead carrier` or noise, the circuit mutes the speaker to avoid annoying noise. Ul amplifies speech and drives rectifier D1/D2 and switch Ql. Comparator U3 drives speaker switch Ql and indicator LED1. Q2 completes the speaker path to ground. U2 is an audio amplifier to drive the speaker. R3 is a volume control. PL1 connects to the scanner speaker or to the headphone jack . 

Build a Scanner Voice Squelch Circuit Diagram

Build a Scanner Voice Squelch Circuit Diagram

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Sunday, August 4, 2013

Stepper Motor Controller

Stepper motors are available in several models and dimensions with various working voltages. The advantage of this general-purpose controller is that is can be utilized with a selection of working voltages, from approximately 5 V to 18 V. It can force the motor with a top voltage equal to half the provide voltage, so it will presumably simply deal with stepper motors designed for voltages between 2.5 V and 9 V. The circuit may additionally supply motor currents up to 3.5 A, which means that it will be used to power relatively massive motors. The circuit is also short-circuit proof and has built-in over temperature protection. Two indicators are required for riding a stepper motor. In logical time periods, they constitute a Grey code, this way that they're two square-wave alerts with the identical frequency but a continuing phase difference of 90 degrees. IC1 generates a square-wave sign with a frequency that could be set the use of potentiometer P1. 

This frequency decides the rpm of the stepper motor. The Grey code is generated by means of a decimal counter in the type of a 4017. Outputs Q0–Q9 of the counter go high in succession based on the rising edges of the clock signal. The Grey code might be generated from the outputs by way of using two OR gates, which are formed right here the usage of two diodes and a resistor for each and every gate, to provide the I and Q alerts. Here ‘I’ stands for ‘in-phase’ and ‘Q’ for ‘quadrature’, which approach that it has a 90-degree phase offset from the I signal. It is standard observe to force the windings of a stepper motor the usage of a pair of push-pull circuits for each winding, which is referred to as an ‘H bridge’. 

That makes it that which you may suppose of to reverse the path of the present through each and every winding, which is necessary for proper operation of a bipolar motor (one whose windings shouldn't have centre faucets). Of direction, it may additionally be used to right kindly pressure a unipolar motor (with centre-tapped windings). Instead of using a push-pull circuit of this okind, right here we made up our minds to use audio amplifier ICs (type TDA2030), even supposing that could sound a bit of bizarre. In functional terms, the TDA2030 is in fact a sort of power opamp. It has a difference amplifier on the enter and a push-pull pressurer stage on the output.

Circuit diagram:
Stepper Motor Controller Circuit Diagram

IC3, IC4 and IC5 are all of this sort (which is economically priced). Here IC3 and IC4 are wired as comparators. Their non-inverting inputs are pushed through the up to now mentioned I and Q indicators, with the inverting enters set to a possible equal to half of the availability voltage. That possible is supplied with the help of the 0.33 TDA2030. The outputs of IC3 and IC4 subsequently observe their non-inverting inputs, and each and every of them powers one motor winding. The different ends of the windings are in turn related to half of the availability voltage, supplied through IC5. As one finish of each winding is hooked up to a square-wave sign that alternates between zero V and a possible close to the provision voltage, while the opposite end is at 1 of 2 the provision voltage, a voltage equal to half the provide voltage is all the time applied to every winding, however it alternates in polarity in okayeeping with the states of the I and Q indicators.

That’s precisely what we wish for riding a bipolar stepper motor. The rpm might be assorted using potentiometer P1, however the precise pace is totally different for every kind of motor as a consequence of it will depend on the choice of steps per revolution. The motor used in the prototype developed with the aid of roughly 9° per step, and its pace may be adjusted over a vary of roughly 2 to 10 2nds per revolution. In idea, any desired pace might be bought by means of adjusting the worth of C1, so long as the motor can handle it. The adjustment range of P1 can be elevated by lowering the worth of resistor R5. The adjustment vary is 1:(1000 + R5)/R5, the place R5 is given in k.If a stepper motor is swaped off by means of removing the availability voltage from the circuit, it’s possible for the motor to continue fliping a specific amount because of its personal inertia or the mechanical load on the motor (flywheel impact).

It’s also possible for the position of the motor to disagree with the states of the I and Q signals when power is first applied to the circuit. As a end result, the motor can on occasion ‘get confused’ when beginning up, with the finish outcome that it takes a step in the wrong path sooner than beginning to transfer in course defined through the force indicators. These impacts might be kept away from by way of including the optional change S1 and a 1-k resistor, which can then be used to begin out and prevent the motor. When S1 is closed, the clock signal stops however IC2 continues its output degrees at that second, so the continual currents during the motor windings magnetically ‘lock’ the rotor in place. The TDA2030 has inside over temperature safety, so the output present will almost surely be decreased robotically if the IC transforms too scorching. For that cause, it is recommended to suit IC3, IC4 and IC5 to a heat sink (possibly a shared heat sink) when a relatively high-power motor is used. The tab of the TO220 case is electrically bonded to the poor provide voltage pin, so the ICs will be attached to a shared heat sink with out the use of insulating washers.


http://www.ecircuitslab.com
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Saturday, August 3, 2013

2001 Pontiac Grand Prix Wiring Diagram

2001 Pontiac Grand Prix Wiring Diagram
(click for full size image)


The Part of 2001 Pontiac Grand Prix Wiring Diagram: camshaft, fuse block, ignition ctrl module, yellow
wire, blue wire, black wire, white black, camshaft position sensor, powertrain control module, knock sensor, camshaft position signal, engine speed signal, crankshaft position sensor, ignition control module, timing control, timing signal.
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Friday, August 2, 2013

Versatile DC DC Converter

Here is a versatile power coupler that connects a device to 5V-19V DC generated from AC mains by a power adaptor. Power adaptors come in different voltage outputs like 5V (for mobile phones), 12V (for external hard drives) and 19V (for laptops). Sometimes the power adaptor may have a voltage rating higher than the required voltage. With the converter circuit given here, the adaptor can be used to power any device at a lower voltage. 

For instance, by using a 19V laptop adaptor, you can power a TTL circuit at 5V. There can also be other instances when one needs a 3V or 6V supply. All these and many other intermediate voltages are easily possible with this versatile converter circuit when used together with any off-hand power adaptor.

Circuit diagram :
Versatile DC-DC Converter-Circuit diagram
Versatile DC-DC Converter Circuit diagram

Fig. 1 shows the circuit of the DC-DC converter. Smooth reduction in the voltage is achieved using the LM317 regulator IC. The complete unit can fit inside a piece of a glue stick tube.
Adjusting variable resistor VR1 gives the desired output voltage. The output voltage is read using a 0-100µA ammeter, whose series resistance R* is chosen such that the maximum desired voltage could be covered. For instance, if full-scale deflection (FSD) current of the meter is 100 µA and you need an output voltage of up to 15V, then R* = 15/0.0001 = 150 kΩ. The desired value of R* is obtained by using 150-kilo-ohm preset VR2. 

Use of a variable resistor which also has an on/off switch like the one in old radios is recommended. It will cut off the coupler from the input power supply without having to accomodate an additional switch. Also, use a heat-sink with LM317 to handle the desired amount of power.

Proposed-assembly

Assemble the circuit on a small general-purpose PCB and enclose in a suitable case. Fit the entire PCB inside a glue stick tube as shown in Fig. 2. Affix the female and male connectors on the opposite ends and place the ammeter in between the stick tube. You can directly read the output voltage on the ammeter after due calibration.

Note. You can use a suitable VU meter instead of 0-100µA ammeter and calibrate accordingly.
 
 
 
Source By Streampowers
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Thursday, August 1, 2013

Motorbike Alarm

This simple to build alarm can be fitted in bikes to protect them from being stolen. The tiny circuit can be hidden anywhere, without any complicated wiring. Virtually, it suits all bikes as long as they have a battery. It doesnt drain out the battery though as the standby current is zero. The hidden switch S1 can be a small push-to-on switch, or a reed switch with magnet, or any other similar simple arrangement. The circuit is designed around a couple of low-voltage MOSFETs configured as monostable timers. Motorbike key S2 is an ignition switch, while switch S3 is a tilt switch. Motorbike key S2 provides power supply to the gate of MOSFET T2, when turned on. 
 
When you turn ignition off using key S2, you have approximately 15 seconds to get off the bike; this function is performed by resistor R6 to discharge capacitor C3. Thereafter, if anyone attempts to get on the bike or move it, the alarm sounds for approximately15 seconds and also disconnects the ignition circuit. During parking, hidden switch S1 is normally open and does not allow triggering of mosfet T1. But when someone starts the motorbike through ignition switch S2, MOSFET T2 triggers through diode D1 and resistor R5. Relay RL1 (12V, 2C/O) energises to activate the alarm (built around IC1) as well as to disconnect the ignition coil from the circuit. Disconnection of the ignition coil prevents generation of spark from the spark plug. Usually, there is a wire running from the alternator to the ignition coil, which has to be routed through one of the N/C1 contacts of relay RL1 as shown in Fig.1 Fig.2 shows the pin configurations of SCR BT169, MOSFET BS170 and transistor BC548.
 
Circuit diagram :

Motorbike Alarm-Circuit-Diagram
 Motorbike Alarm Circuit Diagram
Motorbike Alarm-Pin Configurations :

Motorbike Alarm-Pin configurations
Pin configurations of BT169, BS170 and BC548
 
Also, on disconnection of the coil, sound generator IC UM3561 (IC1) gets power supply through N/O2 contact of relay RL1. This drives the darlington pair built around T3 and T4 to produce the siren sound through loudspeaker LS1.  To start the vehicle, both hidden switch S1 and ignition key S2 should be switched on. Otherwise, the alarm will start sounding. Switching on S1 triggers SCR1, which, in turn, triggers MOSFET T1. MOSFET T1 is configured to disable MOSFET T2 from functioning. As a result, MOSFET T2 does not trigger and relay RL1 remains de-energised, alarm deactivated and ignition coil connected to the circuit.  Connection to the ignition coil helps in generation of spark from the spark plug. Keeping hidden switch S1 accessible only to the owner prevents the bike from pillaging. Tilt switch S3 prevents attempt to move the vehicle without starting it. Glass-and metal-bodied versions of the switch offer bounce-free switching and quick break action even when tilted slowly. 
 
Unless otherwise stated, the angle by which the switch must be tilted to ensure the contact operation (operating angle), must be approximately 1.5 to 2 times the stated differential angle. The differential angle is the measure of the just closed position to the just open position. The tilt switch has characteristics like contacts make and break with vibration, return to the open state at rest, non-position sensitivity, inert gas and hermetic sealing for protection of contacts and tin-plated steel housing. If you find difficulty in getting the tilt switch, you may replace it with a reed switch (N/O) and a piece of magnet. The magnet and the reed switch should be mounted such that the contacts of the switch close when the bike stand is lifted up from rest.
 
 
 
Streampowers
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