Wednesday, June 29, 2011

555 timer IC Based Simple Servo Controller

555 timer IC Based Simple Servo Controller555 timer IC Based Simple Servo Controller

Servos became valuable products for any variety of plans, like robotics, automation or only remotely controlling some thing, for example model vehicle steering. They're reasonably low-priced and also simple to have hold of, however controlling them can be a little challenging while they requrie specific moment to control the output to advance into a preferred position.

Almost all servos use a 50Hz refresh rate (20ms) for level a beat of among 1 and 2ms is required to control the output to advance among -45degrees and +45degrees.

THE 555 timer may be used to control the output using a simple circuit and modified employing a potentiometer.

The circuit is quite self instructive. We start using a 555 timer IC to build the pulse each 20ms which has a responsibility cycle of among 5 and 10% (1-2ms). All of the components employed are common components. You are able to drive several servos with the identical signal by using circuit to all or any have same output or create multiple driver circuits to control several servos to various outputs.

Servos run with a voltage among 5 and 6V, don't exceed this or you can injury them. Although the 555 timer could operate up to 15V.

Also be aware that servos require much current when commanding them also to maintain a location below load, this is around several amps! And so make notice of the while creating your electrical power supply.
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Tuesday, June 28, 2011

115 Volt Infrared Remote Control

115 Volt Infrared Remote Control115 Volt Infrared Remote Control Circuit Diagram

This circuit will allow you to turn on any piece of equipment that operates on 115 volts ac. The receiver circuit is based on the Radio Shack infrared receiver module (MOD), part number 276-137. It is also available from some of the other sources listed on my Links page. The MOD accepts a 40khz IR signal that is modulated at 4 khz. When a signal is received the MOD will go low. The sensitivity of the MOD is set by different values for R1 and C1.

The values for R1 may need to be as high as 10,000 ohms and for C1 40uf. This will prevent the unit from turning on under normal lighting conditions. You will need to experiment with the values that work best for you. The output of the 4013 chip a flip flop toggles on and off with the reception of a IR pulse. The output of the 4013 turns on the MOC optical coupler which in turn switches on the triac and supplies power to the AC load.
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TIP2955 for 78xx Current Booster

Volt regulators such as the LM78xx series sometimes need to provide a little bit more current then they actually can handle. If that is the case, this circuit can help out. A power transistor such as the TIP2955 or similar can be used.
TIP2955 for 78xx Current Booster Circuit
The power transistor is used to boost the extra needed current above the maximum allowable current provided via the regulator. Current up to 1.5 A will flow through the regulator, anything above that makes the regulator conduct and adding the extra needed current to the output load. It is no problem stacking power transistors for even more current. Both regulator and power transistor must be mounted on an adequate heatsink.
78xx Pins
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Monday, June 27, 2011

Regulated DC power supply

Regulated DC power supplyRegulated DC power supply

This PSU has been especially designed for current-hungry ham radio transceivers. It delivers safely around 20Amps at 13.8V. For lower currents, a separate current limiting output, capable of 15ma up to a total of 20A has been added. The power transformer should be capable to deliver at least 25A at 17.5 to 20V. The lower the voltage, the lower power dissipation.

The rectified current will be "ironed" by C1, whose capacity should not be less than 40.000uF, (a golden rule of around 2000uF/A), but we recommend 50.000uF. This capacity can be built up by several smaller capacitors in parallel. The base of this design is a simple 12V regulator (7812). The output voltage can be brought to desired value (here 13.8V) by two external resistors (R5 and R6) using this formula:
U= 12(1+R5/R6)

The low currents (here 15mA) will keep the 7812 in its regular function. As soon as the current rises over 15ma, the voltage drop on R4 will "open" the Q3, actually handling the high output current. This is a PNP transistor (Ic > 25) and current amplification factor of at least 20. The one that has been tested and proven here is the 2N5683.

The current limiting resistance RL, for the maximum output of 20 Amps should be 0.03 Ohms, rated at least 15W. You can use the resistance wire or switch several resistors in parallel, totaling the resistance/power values. Values for other currents can be calculated by the rule:
RL=0.7/Imax

The RL and Q2 (3A PNP such as BD330) form a short circuit automatic fuse. As soon as the maximum current reaches 20Amps, the voltage drop over the resistor RL will open Q2, and thus limit the B-E Current of Q3. Parallel to Q2 is Q1, which lights the LED 1 whenever the current limiting circuit is active. When the fuse is active, the Q2 bridges the R3, so the full current would flow through the IC1, and damage it. Therefore the R4 is inserted, as to limit the IC1 current to 15mA. This makes it possible to run the IC1 without any cooling aid. The LED 2 will light up every time the PSU is switched on. There is an adjustable current limiter in parallel to the fixed output, thus providing adjustable current source for smaller currents.

This circuit is very simple too. You will notice that there is no current sensing resistor. But it is really there, in a form of the Rds-on resistance of the N-channel FET, which actually handles the load cutoff from the source. The function of the FET is shown in the diagram 2. When the current Id is rising, the tension Uds over the resistance Rds rises very slowly in the beginning, but very fast after the knick. This means, that before the knick the FET behaves as a resistor but after it, works as constant current source.

The D2, R3 and B-E connection of the Q4 will sense the Uds voltage of the FET1. When the voltage rises enough, the Q4 will shortcut the FET1 gate to mass, and cut the current flow through the FET 1 off.

However, to enable the FET1 to open, there is certain gate voltage necessary, which in this case is brought up by the voltage divider consisting of R8, Z1, P1 and R9. So the maximum Gate voltage will be the one of the Z1, and the minimal will be around 3V6. The Z1 voltage (Uz1) will thus determine the max current flowing through the FET 1. The diagram 2 will show that for 5 Amps the Uz1 should be 5V6, and for 20Amps around 9V6.

The Capacitor C4 will determine the “velocity” or the reaction time of the limiter. 100 uF will make the reaction time to be around 100ms, and 1n will make it 1us. Within the designed limits, the P1 will limit the current output in the range of 15mA to 20A.

You can use both output simultaneously, but the total output current will be limited by the value of the RL. This PSU can be built also for higher outputs, as long as the transformer will handle the current requirements, and you provide sufficient cooling for the Q3.

Source : www.zen22142.zen.co.uk
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Sunday, June 26, 2011

Battery Charger Solar Panel Atmel ATtiny13V

Battery Charger Solar Panel Atmel ATtiny13VBattery Charger Solar Panel Atmel ATtiny13V

Batwatch is a simple monitor for a solar panel battery charger, using an Atmel ATtiny13V. It periodically measures the allegation accepted and array voltage, and shows them by blinking two LEDs. I congenital this ambit into the bung of a VW solar charger console that is acclimated to anticipate a acquittal of the array back a car is not acclimated for some time. A avant-garde car contains a ample bulk of electronics, and a quiescent accepted of 40-50mA (about 1Ah per day!) is advised "normal"

Every brace of seconds, the software samples the two analog inputs, calculates the allegation accepted and array voltage, and shows the voltage on the red LED and the allegation accepted on the blooming LED. The voltage is apparent in units of 0.1V appliance three decimal digits, and the accepted is apparent in units of 10mA appliance two decimal digits. Anniversary chiffre is represented by a cardinal of abbreviate flashes agnate to the amount of the digit. A aught is represented by a distinct best flash. When the allegation accepted is beneath 10mA (after rounding) or negative, the blooming LED is not angry on at all.

I use 4 times oversampling to get an 11-bit result, afterward the address declared in the Atmel appliance agenda AVR121. I'm not abiding if there is abundant babble on the inputs to absolutely access the resolution, but it will not aching either. The raw A/D account is adapted to a voltage appliance a abstracted brace of offset/gain constants for anniversary input. These constants are acquired from the arrangement abstracts stored in the EEPROM.

To save power, all delays are implemented by active one or added beddy-bye instructions which account the CPU to abandoned until the abutting timer interrupt. The arrest abundance is 100 Hz, so anniversary beddy-bye pauses up to 10 mS.

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Friday, June 24, 2011

2 Cell Lithium Ion Charger

2 Cell Lithium Ion Charger2 Cell Lithium Ion Charger

This circuit was body to allegation a brace alternation Lithium beef (3.6 volts each, 1 Amp Hour capacity) installed in a carriageable transistor radio.

The charger operates by bartering a abbreviate accepted beating through a alternation resistor and again ecology the array voltage to actuate if addition beating is required. The accepted can be adapted by alteration the alternation resistor or adjusting the ascribe voltage. Back the array is low, the accepted pulses are spaced abutting calm so that a somewhat connected accepted is present. As the batteries ability abounding charge, the pulses are spaced further afar and the abounding allegation action is adumbrated by the LED blinking at a slower rate.

A TL431, bandage gap voltage advertence (2.5 volts) is acclimated on pin 6 of the comparator so that the comparator achievement will about-face low, triggering the 555 timer back the voltage at pin 7 is beneath than 2.5 volts. The 555 achievement turns on the 2 transistors and the batteries allegation for about 30 milliseconds. Back the allegation beating ends, the array voltage is abstinent and disconnected bottomward by the aggregate 20K, 8.2K and 620 ohm resistors so that back the array voltage alcove 8.2 volts, the ascribe at pin 7 of the comparator will acceleration hardly aloft 2.5 volts and the ambit will stop charging.

The ambit could be acclimated to allegation added types of batteries such as Ni-Cad, NiMh or advance acid, but the shut-off voltage will allegation to be adapted by alteration the 8.2K and 620 ohm resistors so that the ascribe to the comparator charcoal at 2.5 volts back the terminal array voltage is reached.

For example, to allegation a 6 volt advance acerbic array to a absolute of 7 volts, the accepted through the 20K resistor will be (7-2.5)/ 20K = 225 microamps. This agency the aggregate of the added 2 resistors (8.2K and 620) charge be R=E/I = 2.5/ 225 uA = 11,111 ohms. But this is not a accepted value, so you could use a 10K in alternation with a 1.1K, or some added ethics that absolute 11.11K

Be accurate not to blackmail the batteries. I would acclaim application a ample capacitor in abode of the array to analysis the ambit and verify it shuts off at the actual voltage.

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Wednesday, June 22, 2011

Power Supply AM Farm Radio

Power Supply AM Farm RadioPower Supply AM Farm Radio Circuit Diagram
The affection of the ability accumulation is a Tamura 3FD-410 5V bifold primary/dual accessory transformer. These are accessible from DigiKey.com for reasonable prices. Normally, the transformer's primary windings would be affiliated in alternation for 240VAC operation or in alongside for 120VAC operation. This ambit takes one of the primaries and repurposes it as a 120VAC secondary. For this to work, the agent should be somewhat over-rated, which it is in this case.
The two 5V accessory windings are accumulated in alongside and beatific to a arch rectifier and clarify capacitor to aftermath about 7VDC. This DC voltage is current-limited by a 150 ohm resistor and acclimated to drive two amber LEDs. The LEDs can be hot-glued to the central of the radio aloft the punch to accommodate punch lighting and power-on indication.
The 7VDC is additionally beatific to an LM317 adjustable voltage regulator IC. The LM317 commonly produces a minimum voltage of 1.7V, which is too aerial for this application. A alternation 1N4002 diode is acclimated to bead about .5V to aftermath a minimum voltage of 1.2V. The regulator is adapted so that the filaments accomplish at 1.5VDC.
The 90VDC B+ accumulation uses a arch rectifier beyond the transformer's additional primary ambagious to aftermath about 160VDC. The rectified DC is filtered through a brace of electrolytic capacitors and a alternation resistor. The resistor drops the B+ voltage to the appropriate 90V.
Via : www.solorb.com
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Tuesday, June 14, 2011

3Volt FM Transmitter for 88MHz to 108MHz

3Volt FM Transmitter for 88MHz to 108MHz3Volt FM Transmitter for 88MHz to 108MHz

The important allotment of the circuit is formed of the Colpitts blazon oscillator. C3,C4,C5,C6,CD1-CD2 and L1 determines the frequency. BF982 and bifold aboideau MOSFET are alive genitalia in oscillator. When the ascribe impedance of the MOSFET aboideau inputs are high, LC catchbasin is not affected. However transistors force the LC catchbasin and account appearance shift.

Two disciplinarian stages are added to abstract the antenna from oscillator. First date (BF199) amplifies the low arresting of the oscillator and works as a connected load. The additional date (BFR90) amplifies the arresting activity through the antenna some more. A abbreviate chestnut wire can be acclimated as an antenna here. Attaching a ample antenna to this ambit is accidental because the achievement ability is low.

Notes:

1. Coil 1: Winding wire must be 1 mm thick and isolated. Number of turns: 3.5 . 5mm core must be used and the distance between each turn must be 1mm.
2. You can use BF199 instead of BFR90.
3. If you can't find the varicap diode, you can use MV104 instead.
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2 Transistor FM Transmitter

2 Transistor FM Transmitter2 Transistor FM Transmitter

I accept acclimated a brace of BC548 transistors in this circuit. Although not carefully RF transistors, they still accord acceptable results. I accept acclimated an ECM Mic admit from Maplin Electronics, adjustment cipher FS43W. It is a two terminal ECM, but accustomed activating mic inserts can additionally be used, artlessly omit the advanced 10k resistor. The braid L1 was afresh from Maplin, allotment no.

UF68Y and consists of 7 turns on a division inch artificial above with a affability slug. The affability bang is adapted to tune the transmitter. Actual ambit on my ancestor acquainted from 70MHz to about 120MHz. The aeriform is a few inches of wire. Lengths of wire greater than 2 anxiety may clammy oscillations and not acquiesce the ambit to work. Although RF circuits are best complete on a PCB, you can get abroad with veroboard, accumulate all leads short, and breach advance at adapted points.

One final point, don't authority the ambit in your duke and try to speak. Body capacitance is agnate to a 200pF capacitor shunted to earth, damping all oscillations. I accept had some aboriginal duke acquaintance of this problem. The abundance of cadence can be begin from the approach section,and an archetype now appears in the Ambit Analysis section.

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15dB UHF TV Antenna Booster Circuit

15dB UHF TV Antenna Booster Circuit15dB UHF TV Antenna Booster Circuit

This is an UHF bandage TV antenna preamplifier circuit With 15dB accretion to body easily. It is formed based on BF180 UHF Transistor. The aboriginal date is an bandage canyon clarify complete by the C1, CV1, L1, L4, C7 and C3, the additional date is a base-common voltage amplifier with low ascribe impedance to match. Body the L1 ~ L4 as air amount braid to access aerial Q-Factor. After assembling, backpack it into a able brownish box and affix the arena of the ambit to the box to abate babble effect.
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1 Watt Four Stage FM Transmitter

1 Watt Four Stage FM Transmitter1 Watt Four Stage FM Transmitter

This FM transmitter circuit uses four radio abundance stages: a VHF oscillator congenital about transistor BF494 (T1), a preamplifier congenital about transistor BF200 (T2), a disciplinarian congenital about transistor 2N2219 (T3) and a ability amplifier congenital about transistor 2N3866 (T4). A condenser microphone is affiliated at the ascribe of the oscillator.

Working of the 1 Watt transmitter ambit is simple. When you allege abreast the microphone, frequency-modulated signals are acquired at the beneficiary of oscillator transistor T1.

The FM signals are amplified by the VHF preamplifier and the pre-driver stage. You can additionally use transistor 2N5109 in abode of 2N2219. The preamplifier is a acquainted class-A RF amplifier and the disciplinarian is a class-C amplifier. Signals are assuredly fed to the class-C RF ability amplifier, which delivers RF ability to a 50-ohm accumbent dipole or arena even antenna.

Use a heat-sink with transistor 2N3866 for calefaction amusement (Note: or 2N4427 because it works bigger at 12 V and delivers up to 1 watt RF power). Carefully acclimatize trimmer VC1 affiliated beyond L1 to accomplish abundance aural 88-108 MHz. Additionally acclimatize trimmers VC2 through VC7 to get best achievement at best range.

Regulator IC 78C09 provides abiding 9V accumulation to the oscillator, so aberration in the accumulation voltage will not affect the abundance generated. You can additionally use a 12V array to ability the circuit. Assemble the ambit on a accepted purpose PCB. Install the antenna appropriately for best range.

Coils L1 through L5 are fabricated with 20 SWG copper-enameled wire anguish over air-cores accepting 8mm diameter. They accept 4, 6, 6, 5 and 7 turns of wire, respectively.

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1.5V Battery operated FM Transmitter

1.5V Battery operated FM Transmitter1.5V Battery operated FM Transmitter

This accomplishing is acclimatized to rebroadcast the achievement of a CD player, television receiver, or radio receiver. I use it so that I can move about the abode and accept to my admired programs after advancing others. Within and the house, I acquisition that I can get 10 to 20 meters abroad from the transmitter with the baby abridged FM receiver I backpack in my shirt pocket. Your breadth may vary.

The transmitter as congenital and pictured beneath (the transmitter is in the balloon of hot cook cement on the end of the array holder) does not accept an on-off switch. I put a 1.5 AA corpuscle that was run bottomward too far to run my CD amateur in this transmitter and it ran for over a ages afore I replaced it. The one in the transmitter at this moment has been active it continuously for over three months. Current draw is alone about a milliamp with a new array (assuming you don't accept a super-high beta transistor in which case the abstract absolute is about 2.5 ma). An on-off swich is not necessary, admitting it may amuse an affecting need.

Tips to get it working: Wind the braid on a 4 or 5 mm bore Philips brand screwdriver or agnate anatomy again blooper it off. I acclimated some vinyl cloistral #24 amalgamation wire as able-bodied as #30 enameled wire. In both cases, I played with the breadth of the braid to tune the transmitter to a asleep atom on the FM band. The braid is captivated in abode with hot cook glue. If you don't accept a spectrum analyzer or abundance meter, use a good-quality FM receiver to accomplish abiding its acquainted area you anticipate it is. While adjusting the coil, accumulate in apperception that all superheterodyne receivers accept images. If you acquisition that two or added adjustments accomplish the transmitter appearance up on the aforementioned atom on the receiver, it ability be all-important to booty a abbreviate airing and acquisition out which acclimation drops out aboriginal -this would be the image, because the receiver's advanced end (if it has a acquainted advanced end) will abate its acuteness to the image.

Many kinds of transistors will assignment accomplished in this application. After all, its alone an oscillator (frequency accentuation is acquired my modulating the base-collector voltage, thereby modulating the abyss of the burning band of the reverse-biased base-collector junction, which after-effects in a change in capacitance at the collector, which after-effects in a change the beating abundance of the beneficiary circuit.). I acclimated an 2N4401 because I accept a lot of them. I like 2N3904 and MPSH34 for this too.

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Tuesday, June 7, 2011

Mini FM Transmitter Circuit diagram

Mini FM Transmitter Circuit diagramMini FM Transmitter Circuit diagram

This ambit is a simple two transistor (2N2222) mini FM transmitter. No authorization is appropriate for this transmitter according to FCC regulations apropos wireless microphones. If powered by a 9 volt array and acclimated with an antenna no best than 12 inches, the mini fm transmitter will be aural the FCC limits. The microphone is amplified by Q1. Q2, C5, and L1 anatomy an oscillator that operates in the 80 to 130 MHz range. The oscillator is voltage controlled, so it is articulate by the audio arresting that is activated to the abject of Q2.

R6 banned the ascribe to the RF section, and it’s amount can be adapted as all-important to absolute the aggregate of the input. L1 and C6 can be fabricated with wire and a pencil. The inductor (L1) is fabricated by ambagious two pieces of 24 barometer cloistral wire, laid ancillary by side, about a pencil six times. Remove the braid you accept formed and alleviate the two coils afar from anniversary other. One of these coils (the bigger attractive of the two) will be acclimated in the catchbasin circuit, and the added can be acclimated in the abutting one you build.

The antenna for mini fm transmitter (24 gauge wire) should be soldered to the coil you made, about 2 turns up from the bottom, on the transistor side, and should be 8-12 inches long. To make C6, take a 4 inch piece of 24 gauge insulated wire, bend it over double and, beginning 1/2″ from the open end, twist the wire as if you were forming a rope. When you have about 1″ of twisted wire, stop and cut the looped end off, leaving about 1/2″ of twisted wire (this forms the capacitor) and 1/2″ of untwisted wire for leads.
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Saturday, June 4, 2011

VHF Band TV Transmitter

VHF Band TV TransmitterVHF Band TV Transmitter Circuit Diagram

A VHF band TV transmitter application abrogating complete accentuation and PAL video modulation. This is acceptable for countries application TV systems B and G.

Notes:

The abundance of the transmitter lies aural VHF and VLF ambit on the TV channel, about this ambit has not been activated at UHF frequencies. The articulate complete arresting contains 5.5 -6MHz by affability C5. Complete accentuation is FM and is accordant with UK System I sound. The transmitter about is alive at VHF frequencies amid 54 and 216MHz and accordingly accordant alone with countries application Pal System B and Pal System G.

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