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### Author Topic: help!!  (Read 5190 times)

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#### junjn410

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##### help!!
« on: March 24, 2011, 11:39:26 AM »
first i want ask attach file 2.png . how is the curve function,and , i can't understand.another question is how to calculate it(hold picture)
second, i want to ask about attach file 3.png .is this circuit combine? how to calculate it?
last, have any ic can change to another circuit.i have 3 circuit different effect for led, but i want to use in same led. how can it can change to another circuit automatic? or after a few second will auto change to another circuit.

#### kam

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##### Re: help!!
« Reply #1 on: March 24, 2011, 18:48:07 PM »
hello junjn410. Please set reference links to the drawings like this:
Circuit page: LED Fade-In Fade-Out Dimmer - Circuit #2

Because other people may be interested and they should know from where this schematic comes. Now regarding first attachment.

R1 and R2 makes a voltage divider. According to the position of R2, a specific voltage appears. This voltage is driven through D1 to the base of Q1. This voltage, is the standby voltage for the LEDs, and it keeps the capacitor C1 always charged to this voltage. Because Q2 is in cutoff state (when the button is not pressed), R4-R5-R6 and Q2 do not take part into calculations. To calculate the voltage that arrives at Q1 base, you need to calculate the output voltage of the voltage divider and then subtract the forward voltage drop of D1. Read more for the voltage divider here:  The voltage divider

Quote
last, have any ic can change to another circuit.i have 3 circuit different effect for led, but i want to use in same led. how can it can change to another circuit automatic? or after a few second will auto change to another circuit.

I'm sorry but i do not understand your question

#### junjn410

• Guest
##### Re: help!!
« Reply #2 on: April 02, 2011, 14:57:02 PM »
question 3: can you see 5.jpg. 1 go to 2, next time it will change to 1 to 3/1to4. it will change automatic. any ic can function it?

#### junjn410

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##### Re: help!!
« Reply #3 on: April 02, 2011, 15:20:24 PM »
is it correct circuit? if it has any wrong, correct me pls. thank a lot.

#### kam

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##### Re: help!!
« Reply #4 on: April 02, 2011, 16:47:59 PM »
is it correct circuit? if it has any wrong, correct me pls. thank a lot.

For question 5, you can use the CD4017. you can have up to 10 (or 8 i do not remember) outputs

What is the attached circuit for? It is not clear.

#### junjn410

• Guest
##### Re: help!!
« Reply #5 on: April 03, 2011, 19:26:44 PM »
i attached this circuit for anybody can help me check this circuit, is it correct. i don't know this circuit correct or not, because i never learn electrical before. i want to make some led's effect for my car, so i draw this circuit.

i have another question, how to make sure voltage stable? has any ic or circuit can stable 12v Voltage?

#### kam

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##### Re: help!!
« Reply #6 on: April 03, 2011, 21:01:32 PM »
you can use the 7812 chip to get stable 12 volts, but you need to supply it with ore than 12, for example 13 volts.

#### junjn410

• Guest
##### Re: help!!
« Reply #7 on: April 04, 2011, 18:39:39 PM »
i have two more question,
first, 40Ah = how many A?
second, how many Ampere supply by normal car's battery?

#### kam

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##### Re: help!!
« Reply #8 on: April 05, 2011, 00:14:05 AM »
40 Ah do not determine the maximum amperage of a battery. The Ah is the capacity of the battery. If your battery is 40 Ah, it means that it can provide (theoretically ) 40 amperes for one hour before it runs dry. But the maximum amperage may exceed the 40 amperes. If for example you connect a load that draws 80 amperes, it will provide 80 amperes for half an hour. I do not know what is the maximum amperage.

#### junjn410

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##### Re: help!!
« Reply #9 on: April 05, 2011, 01:50:18 AM »
i want to ask about BC546, how much voltage or ampere it will operate?

#### kam

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##### Re: help!!
« Reply #10 on: April 05, 2011, 07:39:43 AM »
everything you need is in the first page of the datasheet:
http://www.radiotechnika.hu/images/BC546_50.pdf

#### junjn410

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##### Re: help!!
« Reply #11 on: April 05, 2011, 12:19:50 PM »
everything you need is in the first page of the datasheet:
http://www.radiotechnika.hu/images/BC546_50.pdf

i saw it before, but i can't understand it. can u explain it?

#### kam

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##### Re: help!!
« Reply #12 on: April 05, 2011, 23:47:54 PM »
IC it the maximum amperes that can flow through your collector, and therefore the maximum amperes it can control, that will be 100 mA

PC is the maximum power dissipation your transistor can handle, and that is 500mW

Two more characteristics you need to know is the VCBO and VCEO. The first is the max voltage between the collector and the base of the transistor, and the second is the max voltage between the collector and the emitter. VCEO is the one that determines the maximum voltage that can be delivered to your load.

#### junjn410

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##### Re: help!!
« Reply #13 on: April 08, 2011, 00:28:30 AM »
which diode average forward current is 20mA?

#### kam

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##### Re: help!!
« Reply #14 on: April 08, 2011, 07:46:44 AM »
there are two diodes that you will moslty work with, the 1N4148 for small signals (about 200mA) and the 1N4004 for 1A