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    PC817 optocoupler in Darlington configuration with 2N4401 OR ANY NPN

    Thanks for verification, yes i will put diode across relay if i use mechanical relay. I think for SSR i don't need any such protection.
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    PC817 optocoupler in Darlington configuration with 2N4401 OR ANY NPN

    Can i use this configuration to drive 12 VDC SSR Relay or 12 VDC Coil Relay ? Please suggest do i need to keep 220R Resistor in between 2 Transistor ? If i use as darlington pair directly will it damage PC817 ? Please suggest.
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    Relay Contact Sticking Problem when start 1HP AC Motor

    Ammeter shows 20A only for 1 Second and then its normal 7-8Amp @ 230VAC.
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    Relay Contact Sticking Problem when start 1HP AC Motor

    In the Image... i am trying to put 30A 12V Relay OMRON G8P-1A4P 12VDC parallel to Push Start Button (Dual Starter control for 1HP Pump Motor). But every time relay picks up contact stick... Before using Relay i was using 25A 24-480VAC SSR (Zero Crossing) but 4-5 of them failed due to large Surge...
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    [AVR] Driving Large 2.3" 7 Segment Display serially using MAX7219

    Wonderful....it worked like charm :) working normal. Just used Positive side driver UDN2981 and Sink side directly to MAX7219. Initially i though it would get hot, but nothing. Thanks...for your support.
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    [AVR] Driving Large 2.3" 7 Segment Display serially using MAX7219

    The schematic shown about is what i am trying implement. Just problem is 74HC540 is not available with me. Is there any other option to drive 2.3" Inch Large seven segment display from MAX7219 ? I have read datasheet and it says. it can sink 500mA max for total of 8 digits. I have big 2.3" 4...
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    [AVR] Using PNP S8550 Transistor with Atmega8

    I have no direct connection from Microcontroller. Microcontroller DRIVES optocouple in turn opto PC817 drives Gnd path. Do you have any scheme that drives PC817 (NPN Transistor) another NPN transistor's base ? then please show us Schematic.
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    [AVR] Using PNP S8550 Transistor with Atmega8

    Finally i've got something easy Thanks for your suggestion..
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    [AVR] Using PNP S8550 Transistor with Atmega8

    I don't understand why datasheet says maximum voltage is -5V to the base ? How do i calculate that from resistor positions ?
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    [AVR] Using PNP S8550 Transistor with Atmega8

    mistake: Transistor is upside down. (Ignore) ACtually with this design it works. but transistor blows. As base voltage is more than -5V as per datasheet. Thanks.
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    [AVR] Using PNP S8550 Transistor with Atmega8

    Hi, I want to use PNP Transistor being driver from pc817(NPN) Optocoupler which is driven by Atmega8. Can anyone give me stable circuit to drive the relay 155ohm 12V 30A?
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    [AVR] Atmega8 Digital input using 4n35 optocoupler

    Hi, I found the problem. It was DDRB bit which was set to be in output direction. DDRB = 0xFF; but still i was able to use external push button with no issues. That's strange. But as soon as i made it DDRB = 0x00; i am able to detect the opto-coupler signal and now my circuit is optically...
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    [AVR] Atmega8 Digital input using 4n35 optocoupler

    I want to take the field Digital inputs using opto-coupler 4n35 as i have show in the above schmatic. But such arrangement is not working with Atmega8 in the Real hardware. I don't know the reason...actually when i check with multimeter. when the led source is on the PIN5 reads 60mv and when the...
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    [AVR] Atmel Attiny2313 Simple Push Switch Counter Reset issue

    Hi, I am trying to make simple Increment counter based on push switch. When i press switch the counter increments on LCD(16x2) but varialble(Incrementing) again goes to zero in next cycle. I have define that variable as Volatile so it won't be affected by Optimization of GCC compiler. My Code...
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    [AVR] how to write to 16 Bit timer value in MikroC AVR ?

    Hi, I had a situation where i have write 31250 to timer1 in Mikroc for AVR for ATTiny2313. But in mikroc is not accepting TCNT1 = 31250. It asks for TCNT1H & TCNT1L. so how can i create > greater than condition with hex codes ? for I want to create program to toggle led when TCNT1 total count...
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