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how I gain more current to heat a wire??? — Parallax Forums

how I gain more current to heat a wire???

yeyopryeyopr Posts: 3
edited 2007-07-27 02:05 in BASIC Stamp
i want to heat a wire and I made a proram in basic that will turn on and off automatically one output...but when I put the wire on the output doesn't do anything..and when I connected the wire directed to the power supply it work..but i need to heat the wire automatically with the software... I tried to heat the wire with 2 AA battery (3V) and it works...so I think that· I need more current from the microcontroller.... I measured the voltage at the output and it's 5 volts the same as the power supply..that's why I think is the current....

Comments

  • sasukesasuke Posts: 9
    edited 2007-07-26 22:01
    im new to electronics but i would try a capacitor

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  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2007-07-26 22:55
    Trying to heat the wire directly off the I/O line will damage it if you haven’t already. I’m sure to the I/O pin the wire looks like a short circuit. You will need a MOSFET or transistor driver to do what you’re proposing. There are a few transistor and MOSFET circuits posted on these forums that could do this. Take care.

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    Parallax Tech Support
  • yeyopryeyopr Posts: 3
    edited 2007-07-26 23:08
    thanks chris...that's right it's create a short circuit....I have BJT's at my place but I don't know the perfect configuration to gain the current needed....can you tell me what kind of transistor or configuration it's perfect for that...beacause there's a lot of forums there and I don't find it.
  • pwillardpwillard Posts: 321
    edited 2007-07-26 23:27
    Try creating a circuit that uses a relay driven by transistor using stamp I/O. The relay will close a circuit with the wire and the battery and are completly isolated from the stamp. The sudden high current draw of a wire heating up, (dead short) on the stamp power supply side could activate the brown out detetctor or worse... cause erratic bahavior of the stamp. Batteries or Large charged capacitors are good at delivering high current quickly... the relay just isolates and simplifies the circuit.
  • RDL2004RDL2004 Posts: 2,554
    edited 2007-07-26 23:38
    Yes, you're most likely going to have to figure out how to control a relay or a transistor which will in turn switch or control the current to the wire. But why do you want to heat this wire? And why do you think you need to do it with a Basic Stamp? Depending on what you're trying to accomplish, there may be better ways to do it.

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  • yeyopryeyopr Posts: 3
    edited 2007-07-26 23:50
    well Rick... I'm working on a valves design project..and basically I build a prototype using like a medicine syringe and on the stick that you push, on the end I put this wire and inside the syringe I have an air balloon so Iwant that balloon to explode and give air pressure to the liquid that's in the syringe to get out of there....so I need to heat the wire automatically and using a software...so I'm using the parallax board to do that.....
  • FranklinFranklin Posts: 4,747
    edited 2007-07-27 00:34
    www.robotics.com/highload.html

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  • RDL2004RDL2004 Posts: 2,554
    edited 2007-07-27 02:05
    Well, I think it sounds like you basically want to pop a balloon with a hot wire. You might want to check into what the model rocketry people do to ignite their motors.

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