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Help, can't find my IR receiver window!
Posted 07 March 2005 - 01:39 PM
I have a 15 ohm resistor since I bought the 500 1/4W assortment pack, so I should be good to go.
<newbie>The transistor has 3 pins: collector, base, and emitter. Which pin connects to what?
Also, can I leave this project downstairs in my basement, and run 2 wires to upstairs where the LED is, or does it have to be close to the LED?</newbie>
The package shows that "Ic" is 200mA, is that the minimum required mA the VDC powersupply has to support? Last but not least, the package says Vebo = 6V, do I still have the right part (since you mention a 12VDC power supply)? Thanks
Posted 07 March 2005 - 02:05 PM
Don't worry about the specs you saw like Vebo, these are maximum pin to pin voltages that the device can withstand. Vebo would be a maximum emitter to base voltage, we're not exceeding more then 2 or 3 volts with a current limiting resistor (the 2.2k part).
The IR LED is actually being driven at very high peak currents (close to 1 amp) for very short pulse durations. This is ok because the pulses are so short that it cannot heat up the LED or the transistor to any degree. Handheld remotes work the same way too.
Posted 07 March 2005 - 02:07 PM
Posted 07 March 2005 - 02:25 PM
In the circuit diagram, the emitter is at the bottom (the one with the arrow), the base goes to the 2.2 resistor, and the collector goes to the 15 ohm and IR LED part of the circuit.
Enen the most ordinary DC wall wart has a filter capacitor that can provide a large current for a very short time, measured in microseconds. If the wall wart is only 200 mA or so, it might be a good idea to add an extra filter capacitor across it for more current capacity. If you can get a can-type capacitor rated for 220 or 470uF (or more) at 25 Volts then add that across the +12v supply for extra oomph.
Posted 07 March 2005 - 02:29 PM
Posted 07 March 2005 - 02:59 PM
Posted 08 March 2005 - 08:56 PM
I know it looks bad, but that's all I had to work with
The 2 black cables go to the mini plug which plugs in to the Ocelot
The stereo wiring goes to the female mini jack which is where I plugin my LED using a male mini jack I put together
I found a universal powersupply, set to 12VDC, providing around 300mA, but I don't think it's regulated. When I measure the 2 contact terminals connected to the speaker wiring (IR LED), it measures 9.33VDC all the time, and around 9.60-9.80VDC when the Ocelot transmits an IR command.
Is it possible at all to tell from the picture if I did something wrong or should I just get a breadboard and redo it?
Posted 08 March 2005 - 09:34 PM
Posted 08 March 2005 - 10:10 PM
Posted 08 March 2005 - 10:39 PM
Posted 08 March 2005 - 10:46 PM
The pulses are so short that you'll never be able to see them with any accuracy with just a voltmeter. You would need a scope to do that. One thing you might try is adding a visible LED to the output side to see any activity. To do that, add a visible LED and a 1k resistor in "parallel" like this:
+12v---------IR LED-----15 ohm R------------->to transistor collector
+12v------Visible LED----470 ohm R----------->to transistor collector
Posted 08 March 2005 - 10:54 PM
I found an online manual for this transistor, which also contains the pinout information:
Do you still think I have it wrong? I will switch it tomorrow (and maybe try to get a small breadboard). Thanks Guy!
PS: Wouldn't I be able to detect the IR using my Digital Camera, or is it too fast for that as well?
Posted 09 March 2005 - 01:12 AM
Resistor Color Code Utility
Might be my eyes though as I had a tough day at work and its late here.
As far as the transistor, look HERE on page two (TO-92 type case).
Edited by BraveSirRobbin, 09 March 2005 - 01:36 AM.
Posted 09 March 2005 - 07:56 AM
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