Showing posts with label for. Show all posts
Showing posts with label for. Show all posts
Sunday, September 21, 2014
Dual Output DC DC Power Supply for AMOLED Displays
This is a dual-output switch mode power supply reference design based on the MAX17116. The part and reference circuit can provide both negative and positive supplies to AMOLED displays. [via]
The MAX17116 includes two current-mode 1.4MHz switch mode power-supply (SMPS) regulators for active-matrix organic light-emitting diode (AMOLED) displays. The positive supply is provided by a step-up regulator with a synchronous rectifier. The negative supply is provided by an inverting regulator with a synchronous rectifier.[Link]
Tuesday, May 14, 2013
LED Pulsere circuit for the Christmas Star
This circuit can be used to decorate your Christmas star.Here the LED light up gradually and disappear gradually.you can attach 6 LEDs for this.Supply 4.5v - 6v for this circuit.Here we have used femous IC LM358 .So you all will be able to find that IC easily.Parts
IC1__________LM358 Low Power Dual Op-amp
Q1___________BC337 45V 800mA NPN Transistor
R1,R2___________4K7 1/4W Resistors
R3_____________22K 1/4W Resistor
R4______________2M2 1/4W Resistor
R5_____________10K 1/4W Resistor
R6_____________47R 1/4W Resistor
C1______________1µF 63V Polyester Capacitor
D1_____________5mm. Red LED
Monday, May 13, 2013
Brightness Controller Circuit For Small Lamps and Leds
This device was designed on request; to control the light intensity of four filament lamps (i.e. a ring illuminator) powered by two AA or AAA batteries, for close-up pictures with a digital camera. Obviously it can be used in other ways, at anyones will.IC1 generates a 150Hz square wave having a variable duty-cycle. When the cursor of P1 is fully rotated towards D1, the output positive pulses appearing at pin 3 of IC1 are very narrow.
Bulb LP1, driven by Q1, is off as the voltage across its leads is too low. When the cursor of P1 is rotated towards R2, the output pulses increase in width, reaching their maximum amplitude when the potentiometer is rotated fully clockwise. In this way the bulb reaches its full brightness.
Parts:
P1 = 470K
R1 = 10K
R2 = 47K
R3 = 1.5K
C1 = 22nF-63V
C2 = 100uF-25V
D1 = 1N4148
D2 = 1N4148
Q1 = BD681
B1 = 2xAA cells in series
IC1 = 7555 or TS555CN
LP1 = 1.5V 200mA Bulb
SW1 = SPST Switch
Notes:
* LP1 can be one or more 1.5V bulbs wired in parallel. Maximum total output current allowed is about 1A.
* R2 limits the output voltage, measured across LP1 leads, to 1.5V. Its actual value is dependent on the total current drawn by the bulb(s) and should be set at full load in order to obtain about 1.5V across the bulb(s) leads when P1 is rotated fully clockwise.
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Bulb LP1, driven by Q1, is off as the voltage across its leads is too low. When the cursor of P1 is rotated towards R2, the output pulses increase in width, reaching their maximum amplitude when the potentiometer is rotated fully clockwise. In this way the bulb reaches its full brightness.
Parts:
P1 = 470K
R1 = 10K
R2 = 47K
R3 = 1.5K
C1 = 22nF-63V
C2 = 100uF-25V
D1 = 1N4148
D2 = 1N4148
Q1 = BD681
B1 = 2xAA cells in series
IC1 = 7555 or TS555CN
LP1 = 1.5V 200mA Bulb
SW1 = SPST Switch
Notes:
* LP1 can be one or more 1.5V bulbs wired in parallel. Maximum total output current allowed is about 1A.
* R2 limits the output voltage, measured across LP1 leads, to 1.5V. Its actual value is dependent on the total current drawn by the bulb(s) and should be set at full load in order to obtain about 1.5V across the bulb(s) leads when P1 is rotated fully clockwise.
Tuesday, April 30, 2013
Soft Start For Switching Power Supply
Switching power supply whose output voltage is appreciably lower than its input voltage has an interesting property: the current drawn by it is smaller than its output current. However, the input power (UI) is, of course, greater than the output power. There is another aspect that needs to be watched: when the input voltage at switch-on is too low, the regulator will tend to draw the full current. When the supply cannot cope with this, it fails or the fuse blows. It is, therefore, advisable to disable the regulator at switch-on (via the on/off input). until the relevant capacitor has been charged. When the regulator then starts to draw current, the charging current has already dropped to a level which does not overload the voltage source.
Circuit diagram:
Circuit diagram:
Soft Start Circuit For Switching Power Supply
The circuit in the diagram provides an output voltage of 5 V and is supplied by a 24 V source. The regulator need not be disabled until the capacitor is fully charged: when the potential across the capacitor has reached a level of half or more of the input voltage, all is well. This is why the zener diode in the diagram is rated at 15 V. Many regulators produced by National Semiconductor have an integral on/off switch, and this is used in the present circuit. The input is intended for TTL signals, and usually consists of a transistor whose base is accessible externally. This means that a higher switching voltage may be applied via a series resistor: the value of this in the present circuit is 22 kΩ. When the voltage across the capacitor reaches a level of about 17 V, transistor T1 comes on, whereupon the regulator is enabled.
Source: National Semiconductors
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