Monday, December 23, 2013
12V Touch Switch Exciter
This circuit is designed to generate a 20KHz pseudo sine wave signal that can power about 50 remote touch activated switch circuits. It can support a cable length of about 2500 feet. A typical remote switch circuit is also shown as well as a receiver circuit for those switches.
Source: DiscoverCircuits
Sunday, December 22, 2013
Simple Video Amplifier
The video amplifier in the diagram is a well-known design. Simple, yet very useful, were it not for the ease with which the transistors can be damaged if the potentiometers (black level and signal amplitude) are in their extreme position. Fortunately, this can be obviated by the addition of two resistors.
Circuit diagram :
Simple Video Amplifier Circuit Diagram
If in the diagram R 3 and R 4 were direct connections, as in the original design, and P 1 were fully clockwise and P 2 fully anticlockwise, such a large base current would flow through T 1 that this transistor would give up the ghost. Moreover, with the wiper of P 2 at earth level, the base current of T 2 would be dangerously high. Resistors R 3 and R 4 are sufficient protection against such mishaps, since they limit the base currents to a level of not more than 5 mA.
Shunt capacitor C 4 prevents R 4 having an adverse effect on the amplification.
Saturday, December 21, 2013
Build a Inexpensive Isolation Transformer Circuit Diagram
Build a Inexpensive Isolation Transformer Impromptus Setup Circuit Diagram. Using two 12-V filament or power transformers, an impromptu isolation transformer can be made for low-power (under 50 W) use in testing or servicing. SOI is an ordinary, duplex ac recept-able. Use heavy-wire connections between the 12-V windings because several amperes can flow.
Inexpensive Isolation Transformer Circuit Diagram
Friday, December 20, 2013
AC 220V Mains Powered Emergency Light and Alarm
This circuit is permanently plugged into a mains socket and NI-CD batteries are trickle-charged. When a power outage occurs, the lamp automatically illuminates. Instead of illuminating a lamp, an alarm sounder can be chosen. When power supply is restored, the lamp or the alarm is switched-off. A switch provides a "latch-up" function, in order to extend lamp or alarm operation even when power is restored.
R1 = 220K
R2 = 470R
R3 = 390R
R4 = 1.5K
R5 = 1R
R6 = 10K
R7 = 330K
R8 = 470R
R9 = 100R
D1 = 1N4007
D2 = 1N4007
D3 = 1N4007
D4 = 1N4007
D5 = 1N4007
D6 = Led
D7 = 1N4148
Q1 = BC547
Q2 = BC327
Q3 = BC547
Q4 = BC547
Q5 = BC327
C1 = 330nF-400V
C2 = 10uF-63V
C3 = 100nF-63V
C4 = 10nF-63V
LP1 = 2.5V-300mA Torch Lamp Bulb
PL1 = Male Mains Plug
SW1 = SPST Switches
SW2 = SPST Switches
SW3 = SPDT Switches
SPKR = 8 Ohms Loudspeaker
B1 = 2.5V Battery (two AA NI-CD rechargeable cells wired in series)
Mains voltage is reduced to about 12V DC at C2s terminals, by means of the reactance of C1 and the diode bridge (D1-D4). This avoids the use of a mains transformer. Trickle-charging current for the battery B1 is provided by the series resistor R3, D5 and the green LED D6 that also monitors the presence of mains supply and correct battery charging.
Q2 & Q3 form a self-latching pair that start operating when a power outage occurs. In this case, Q1 biasing becomes positive, so this transistor turns on the self latching pair. If SW3 is set as shown in the circuit diagram, the lamp illuminates via SW2, which is normally closed; if set the other way, a square wave audio frequency generator formed by Q4, Q5 and related components is activated, driving the loudspeaker.
If SW1 is left open, when mains supply is restored the lamp or the alarm continue to operate. They can be disabled by opening the main on-off switch SW2. If SW1 is closed, restoration of the mains supply terminates lamp or alarm operation, by applying a positive bias to the Base of Q2.
Close SW2 after the circuit is plugged.
The circuit is connected to 230Vac mains, then some parts in the circuit board are subjected to lethal potential!. Avoid touching the circuit when plugged and enclose it in a plastic box.
ReadMore..
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| Emergency Light and Alarm Circuit Diagram |
Parts List:
R1 = 220K
R2 = 470R
R3 = 390R
R4 = 1.5K
R5 = 1R
R6 = 10K
R7 = 330K
R8 = 470R
R9 = 100R
D1 = 1N4007
D2 = 1N4007
D3 = 1N4007
D4 = 1N4007
D5 = 1N4007
D6 = Led
D7 = 1N4148
Q1 = BC547
Q2 = BC327
Q3 = BC547
Q4 = BC547
Q5 = BC327
C1 = 330nF-400V
C2 = 10uF-63V
C3 = 100nF-63V
C4 = 10nF-63V
LP1 = 2.5V-300mA Torch Lamp Bulb
PL1 = Male Mains Plug
SW1 = SPST Switches
SW2 = SPST Switches
SW3 = SPDT Switches
SPKR = 8 Ohms Loudspeaker
B1 = 2.5V Battery (two AA NI-CD rechargeable cells wired in series)
Mains voltage is reduced to about 12V DC at C2s terminals, by means of the reactance of C1 and the diode bridge (D1-D4). This avoids the use of a mains transformer. Trickle-charging current for the battery B1 is provided by the series resistor R3, D5 and the green LED D6 that also monitors the presence of mains supply and correct battery charging.
Q2 & Q3 form a self-latching pair that start operating when a power outage occurs. In this case, Q1 biasing becomes positive, so this transistor turns on the self latching pair. If SW3 is set as shown in the circuit diagram, the lamp illuminates via SW2, which is normally closed; if set the other way, a square wave audio frequency generator formed by Q4, Q5 and related components is activated, driving the loudspeaker.
If SW1 is left open, when mains supply is restored the lamp or the alarm continue to operate. They can be disabled by opening the main on-off switch SW2. If SW1 is closed, restoration of the mains supply terminates lamp or alarm operation, by applying a positive bias to the Base of Q2.
Note:
Close SW2 after the circuit is plugged.
Warning!
The circuit is connected to 230Vac mains, then some parts in the circuit board are subjected to lethal potential!. Avoid touching the circuit when plugged and enclose it in a plastic box.
Thursday, December 19, 2013
Solar Power Supply
This circuit delivers either 4.8 or 7.2 V regulated at 15 mA with a 3-V input from a bank of photocells. Rl should be 453 kQ for a 7.2-V output and 274 РЁ for a 4.8-Vdc output. Regulator efficiency is around 70%. This should be considered when selecting suitable solar cells.
Solar Power Supply Circuit diagram :
Solar Power Supply Circuit diagram :
Wednesday, December 18, 2013
The ordering quantity of this order of Cell Phone Jammers is large enough
The document of Cell Phone Jammers will contain the important product information of Cell Phone Jammers .
The laser has been widely applied to the laser welding, laser cutting, laser drilling (including the slant-hole, different holes, plaster hole, perforated tipping paper, perforated steel, perforated packaging and printing, etc.), laser hardening, laser heat treatment, laser marking, glass engraving, laser trimming, laser lithography, laser system, film, laser film processing, laser packages, laser repair circuits, laser routing technology, laser cleaning.
Periodic illegible: often drum charge roller coating or contamination, watermarks, mimeo, fingerprints often cause this defect. Grapes: It is the same as the overlapping coins appear in the printed materials of a defect, no rules, and difficult to repeat, is caused by bad drum ground. Background scattering: refers to the text or unwanted lines around the black specks, toner from the magnetic roller coating or bad cause. Drum overheating (referring to a sense of high) may also cause this defect. Wave background (tiger grouper): wavy black version in white or white on black version or in the form of half-tone version. Several more kinds of payment method of Cell Phone Jammers will be added for this online store of Cell Phone Jammers .
Usually magnetic roller sleeve coating defects or due to prolonged low-density printing, magnetic bond caused by the magnetic roller sleeve. Hollow words: refers to the text or images is missing strokes on the reasons: toner itself is the problem. Dark pink with bad. Magnetic roller coating problems. Print media over the surface of the light, perfect. Paper with the negative. Irregular vertical black spots: the deformation caused by the sealing of the waste toner smears scattered. As the accumulation of too much toner on the magnetic roller, causing leakage of powder. Coloration: with a variety of factors: the toner itself is the problem. Toner, magnetic roller with the problem. Flour knife aging. Magnetic roller wear. Drums to life. High humidity or moisture absorption media. The detailed information of Cell Phone Jammers contains the ordering quantity of Cell Phone Jammers .
Bottom ash: bottom ash refers to prints blank zone in the mist toner, but also with a variety of factors: aging scraper. Charge roller fouling. Toner problem. Drum fatigue, to life. Low temperature and dry environment. Print media bad. Charge roller wear. Fixing is not strong: refers to the printed text or images on the product that is out of touch. The reasons are: toner softening point higher than the machines fusing temperature. Print media too thick or too light surface. Before cleaning the printer, be sure to carefully read the printer user manual to follow any special procedures and warnings. The ordering quantity of this order of Cell Phone Jammers is large enough.
ReadMore..
The laser has been widely applied to the laser welding, laser cutting, laser drilling (including the slant-hole, different holes, plaster hole, perforated tipping paper, perforated steel, perforated packaging and printing, etc.), laser hardening, laser heat treatment, laser marking, glass engraving, laser trimming, laser lithography, laser system, film, laser film processing, laser packages, laser repair circuits, laser routing technology, laser cleaning.
Periodic illegible: often drum charge roller coating or contamination, watermarks, mimeo, fingerprints often cause this defect. Grapes: It is the same as the overlapping coins appear in the printed materials of a defect, no rules, and difficult to repeat, is caused by bad drum ground. Background scattering: refers to the text or unwanted lines around the black specks, toner from the magnetic roller coating or bad cause. Drum overheating (referring to a sense of high) may also cause this defect. Wave background (tiger grouper): wavy black version in white or white on black version or in the form of half-tone version. Several more kinds of payment method of Cell Phone Jammers will be added for this online store of Cell Phone Jammers .
Usually magnetic roller sleeve coating defects or due to prolonged low-density printing, magnetic bond caused by the magnetic roller sleeve. Hollow words: refers to the text or images is missing strokes on the reasons: toner itself is the problem. Dark pink with bad. Magnetic roller coating problems. Print media over the surface of the light, perfect. Paper with the negative. Irregular vertical black spots: the deformation caused by the sealing of the waste toner smears scattered. As the accumulation of too much toner on the magnetic roller, causing leakage of powder. Coloration: with a variety of factors: the toner itself is the problem. Toner, magnetic roller with the problem. Flour knife aging. Magnetic roller wear. Drums to life. High humidity or moisture absorption media. The detailed information of Cell Phone Jammers contains the ordering quantity of Cell Phone Jammers .
Bottom ash: bottom ash refers to prints blank zone in the mist toner, but also with a variety of factors: aging scraper. Charge roller fouling. Toner problem. Drum fatigue, to life. Low temperature and dry environment. Print media bad. Charge roller wear. Fixing is not strong: refers to the printed text or images on the product that is out of touch. The reasons are: toner softening point higher than the machines fusing temperature. Print media too thick or too light surface. Before cleaning the printer, be sure to carefully read the printer user manual to follow any special procedures and warnings. The ordering quantity of this order of Cell Phone Jammers is large enough.
Tuesday, December 17, 2013
DC Fan Controller
This circuit is ideal to control the cooling fan of heat generated electronic gadgets like power amplifiers. The circuit switches on a fan if it senses a temperature above the set level. The fan automatically turns off when the temperature returns to normal. The circuit uses an NTC (Negative Temperature Coefficient) Thermister to sense heat. NTC Thermister reduces its resistance when the temperature in its vicinity increases.
IC1 is used as a voltage comparator with two potential dividers in its inputs. Resistor R1 and VR1 forms one potential divider connected to the non inverting input of IC1 and another potential divider comprising R2 and the 4.7K Thermistor supplying a variable voltage to the inverting input of IC1. VR1 is adjusted so as to give slightly lesser voltage at the non inverting input than the inverting input at room temperature.
DC Fan Controller Circuit
IC1 is used as a voltage comparator with two potential dividers in its inputs. Resistor R1 and VR1 forms one potential divider connected to the non inverting input of IC1 and another potential divider comprising R2 and the 4.7K Thermistor supplying a variable voltage to the inverting input of IC1. VR1 is adjusted so as to give slightly lesser voltage at the non inverting input than the inverting input at room temperature.
DC Fan Controller Circuit
In this state, output of IC1 will be low and the Fan remains off. When the temperature near the Thermister increases, its resistance decreases and conducts. This drops the voltage at pin 2 of IC1 and its output becomes high. T1 then triggers and fan turn on. Red LED indicates that fan is running. Capacitor C1 gives a short lag before T1 turns on to avoid false triggering and to give proper bias to T1.
DC fan can be the one used in Computer SMPS. Keep the Thermistor near the heat sink of the Amplifier PCB and switch on the amplifier for 10 minutes. Then adjust VR1 till the Fan stop running.When the temperature rises, Fan will automatically switch on.
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