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noidea
Joined: 13 Oct 2004
Posts: 13
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 18 Oct 2004 8:54 about 555 timer & and Voltage stepping down |
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hi,
i have 2 problems here.
1) 555 Timer. is 555 timer able to:
when something is activated(switch or any thing that trigger) the 555 timer can activate a LED and the LED would blink for 5 seconds and goes off on itself. Any1 can help me on the circuit design/diagram on how can it work? thanks..
2) About Voltage stepping down.. is there any other ways i can step down Voltage other den using RESISTORS? Example:
INPUT(12V to sensor) ---> SENSOR ---> OUTPUT(needed 5V going into a IC chip, so i think a Voltage step down method needed to be implemented but any other ways other den using resistors?)
Thanks for reading i hope someone can really help.. Take care 
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nicleo
Joined: 06 Sep 2004
Posts: 717
Helped: 60
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| 18 Oct 2004 10:13 Re: about 555 timer & and Voltage stepping down |
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| noidea wrote: |
hi,
i have 2 problems here.
1) 555 Timer. is 555 timer able to:
when something is activated(switch or any thing that trigger) the 555 timer can activate a LED and the LED would blink for 5 seconds and goes off on itself. Any1 can help me on the circuit design/diagram on how can it work? thanks..
2) About Voltage stepping down.. is there any other ways i can step down Voltage other den using RESISTORS? Example:
INPUT(12V to sensor) ---> SENSOR ---> OUTPUT(needed 5V going into a IC chip, so i think a Voltage step down method needed to be implemented but any other ways other den using resistors?)
Thanks for reading i hope someone can really help.. Take care |
1) As '555 timer' itself implies, you can use it as 'timer' and you can adjust the timer (R and C value) so that your LED can blink according to the time interval you want.
2) You can use linear regulator (7805) or switching regulator (buck converter).
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noidea
Joined: 13 Oct 2004
Posts: 13
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| 18 Oct 2004 11:46 Re: about 555 timer & and Voltage stepping down |
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| hello thanks for the info.. i try to study those kinds of regulators..
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papyaki
Joined: 13 Apr 2002
Posts: 564
Helped: 19
Location: A small village somewhere in Gaul
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| 18 Oct 2004 12:17 Re: about 555 timer & and Voltage stepping down |
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Hi,
For 1), you can use two 555. The first one as a monostable and the second one as an astable. The astable period be the blinking period of the LED diode. The monostable period should be 5 second. The monostable output (3) should be connected to the reset pin (4) of the astable.
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noidea
Joined: 13 Oct 2004
Posts: 13
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| 18 Oct 2004 14:37 Re: about 555 timer & and Voltage stepping down |
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| papyaki wrote: |
Hi,
For 1), you can use two 555. The first one as a monostable and the second one as an astable. The astable period be the blinking period of the LED diode. The monostable period should be 5 second. The monostable output (3) should be connected to the reset pin (4) of the astable. |
hmmm thanks alot.. hmmm. the mono output(3) connect to (4) of astable rite..
but isn't the (4) of astable is connect to ground? so if i am to connect to astable's pin (4) should it be connect to ground too? or the monos output alone connected to astable (4)?
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lokeyh
Joined: 29 Sep 2004
Posts: 208
Helped: 51
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| 18 Oct 2004 15:24 Re: about 555 timer & and Voltage stepping down |
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| Why not use a counter to count 5 seconds and use some combinational logic to mask the output to the LED after that?
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papyaki
Joined: 13 Apr 2002
Posts: 564
Helped: 19
Location: A small village somewhere in Gaul
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| 18 Oct 2004 15:52 Re: about 555 timer & and Voltage stepping down |
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Hi,
You need two 555. The first is a monostable, the second is an astable. In normal astable configuration, reset pin (4) is connected to Vcc. In the configuration I described, it should be disconnected from Vcc and connected to output pin (3) of the monostable.
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noidea
Joined: 13 Oct 2004
Posts: 13
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| 18 Oct 2004 16:15 Re: about 555 timer & and Voltage stepping down |
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ok thanks alot guys for helping.. i will try out the curcuit tomorrow for the 55 timer..
stepping down of voltage stiull working on it 
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