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Beginners / Re: CREE LED, current limited?
« Last post by Belrmar on Today at 06:58:59 AM »

For people experienced with such LEDs, does this sound like a defect (or a zapped LED, though I was careful with ESD band and all), or does the LED need to warm up to its 85C operating temp? Anyway, it seems odd to a power LED newb.

LED's as all diodes , when they get warmer their foward voltage decreases, so it may be a problem with the supply that can't get enough voltage to push 400ma acros your LED
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The data sheet does not seems to specify that 6 volt range.

http://www.ti.com/lit/ds/symlink/ne5532.pdf

still i checked with 6 volt supply and 1 volt input gives output of 1.423 volts.

regarding common mode voltage limit
where in the data sheet has it been mentioned or is there any way to see it.

i tried inputting 0.770 voltage but the output goes high (5 volt output with 6 volt supply)

anything less than 1.2 volt to 0.770 volt the output is is 1.423.... volt..


The opamp you are using is not a rail to rail opamp , so each time you get close to some of the rails it will either output something larger or either go crazy, try doing the same with a split supply, maybe 2 9v batteryes or a fully charged 2s lipo
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Synchronous, time-triggered design will solve most problems of the asynchronous design.
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+1

If you have a complex project, adding more CPUs makes it more complex, never simpler. The only time to consider multiple CPUs is when you have maxed out the CPU package, you have physical separation or need electrical isolation.

The complexity required for reliable comms is often underestimated and can be a nightmare to debug if done poorly. There can be a significant overhead of comms processing, unless you have a very strong logical separation between functions.

I think in nearly the projects I have worked on where multiple CPUs were used, the lesson was always "next time we design this with a single CPU..."
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You might be able to get two crystals separated by a few tens of hertz, mix their outputs, and get a nice low frequency out. The timing accuracy won't be great, but it would be pretty easy to do with discretes.

It will not work. Crystals happen to drift, one could drift faster than another. Could be so that one day clock is running 2x faster and another it is running 20x slower  :-DD
That would be like the compass of Cpt. Jack Sparrow. Hmm... Peanuts.

What about quartz oscillator... A hourglass with electromechanical motor to turn it over.
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While sacrificing accuracy compared to a crystal, a few automotive clocks used a pendulum oscillator, this was a ring with a magnet attached at 1 point, it had 2 drive coils and 1 sense coil, and a restoring spring.

When the magnet went past the sense coil in 1 direction it gave a positive pulse, in the other a negative pulse, which drove the transistors operating the drive coils which gave it a small kick to keep it moving.

I have only repaired 5-6 of these in the past, however almost all of them operated at 2 Hz, 
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Test Equipment / U1461A Question
« Last post by jonkers on Today at 06:49:46 AM »
Hello all. 

I am an I&E Tech and am in the need of a new IR tester.  I currently have a U1282A and i find the bluetooth connection with my phone super handy.

So i was looking at the U1461a but i came across the thread (http://www.eevblog.com/forum/testgear/fluke-289-defective-or-not/msg1424474/#msg1424474) where blueskull was having some issues with firmware bugs and voltage issues.

Was wondering if this was an isolated case or if it is an issue with the meter?  All of the reviews i have read seem to be very positive.

Thanks.

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You might be able to get two crystals separated by a few tens of hertz, mix their outputs, and get a nice low frequency out. The timing accuracy won't be great, but it would be pretty easy to do with discretes.

It will not work. Crystals happen to drift, one could drift faster than another. Could be so that one day clock is running 2x faster and another it is running 20x slower  :-DD
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A year or so ago, we had a talk given by one of our ACMA compliance officers (i think one of about 4 for Australia!), re cell phone jammers - they (ACMA)  are really are clamping down, cinemas and Taxi drivers seem to be some of the common places.
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Quote
If you've already got the circuit, then how about replacing the TIP122 with a suitable MOSFET, such as IRFB3806, IRFZ44Z, IRLB8748, IRLB8721, TK30E06N1, NTD4815N-35G? No other modifications are necessary.

Impossible to remove without destroying the board.  Thanks for the tip though (pardon the pun).
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