Characteristics of electrical current

Discussion in 'The Projects Forum' started by joefly, Apr 16, 2010.

  1. joefly

    Thread Starter New Member

    Apr 14, 2010
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    This is a general question from a non electrical guy.

    I got a circuit working on 3vdc batteries.

    When I take a 5VDC transformer and drop the V with diodes to about 3V, the circuit acts weird. What are the possible differences to the above scenario that could result that using a transformer giving out 3v does not work?

    A different scenario, I got a board that is a keychain remote working off of 5VDc, when the switch is on, there are two terminals that measures 5VDC. I am trying to trip a small relay, but when the relay is powered with this terminal, the relay does not trip. However, it measures 5VDC, and it does light a LED, what are the possible causes that eventhough the terminals measures 5VDC, that it does not trip a small relay. If it is amps, how do I confirm this is the problem or measure it??

    3rd question: Is there a suggested way to drop a 5vdc charger to act like 2XAA batteries? The way I tried above, seems to not work correctly.

    Thanks for your help.
     
    Last edited: Apr 16, 2010
  2. retched

    AAC Fanatic!

    Dec 5, 2009
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    Can you post the schematics of your circuits and maybe a link to the datasheet or product info for the keychain circuit?
     
  3. joefly

    Thread Starter New Member

    Apr 14, 2010
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    0
    Hi Recheted

    I am not able to provide a schematic as this is a cheap board without any instructions. But I did look at the board and see that it is using PT2272-L4 which is the RF remote chip. http://electronics-diy.com/pdf/PT2272.pdf on the data sheet is talks about the output pins.

    I am guessing that this board only provides enough 5V to act as a data signal without much amp to power anything. so the question now becomes, how to I use this signal to power a relay so that I can let a full 5V through??

    Thanks for any suggestions.
     
  4. retched

    AAC Fanatic!

    Dec 5, 2009
    5,201
    312
    You can use a logic level transistor as a switch to allow another power source to switch the relay.

    Are you trying to energize the relay with the RF signal?
     
  5. joefly

    Thread Starter New Member

    Apr 14, 2010
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    0
    the PT2272 chip is on a board that receives on/off from a keychain RF remote. on the board are like 7 posts, a couple for V +/-, others are + and -5VDC that is switched on and off depending on the mode of operation intended and the key button.

    So I am trying to use the on/off keychain to turn on and off another board that is operating on 3Vdc battery. my goal is to first remotely turn my board off and on using the PT2272 board, assuming that the posts are only giving 5vdc signals, how can I use this signal to turn on and off my main board by passing either a 5vdc or 3vdc ideally.

    Someone else did mention to me that I can used a transistor to turn off and on the relay. But what is the circuit layout and how do i chose the right transistor.

    Thanks..

    Well, to put simply, ultimately, I am trying to use the keychain remote to turn on and off my board. The RF is received by the PT2272 board and the on board posts turns off and on accordingly. So how do I take the 5VDC post signals and use it to energize the relay for allowing power to my board .
     
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