Today's Message Index:
----------------------
1. 07:58 AM - Re: AEC 9009 Audio Amplifier Troubleshooting Questions (Jared Yates)
2. 08:14 AM - Re: Photo FET Optocoupler (John Grosse)
3. 08:22 AM - Re: AEC 9009 Audio Amplifier Troubleshooting Questions (Robert L. Nuckolls, III)
4. 08:23 AM - Re: Photo FET Optocoupler (Robert L. Nuckolls, III)
5. 09:39 AM - Re: Photo FET Optocoupler (John Grosse)
6. 09:46 AM - Re: Photo FET Optocoupler (Robert L. Nuckolls, III)
7. 11:34 AM - Re: Photo FET Optocoupler (Daniel Hooper)
Message 1
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| Subject: | Re: AEC 9009 Audio Amplifier Troubleshooting Questions |
Indeed, I had installed the 122 backwards. It works now, thanks!
On Jun 15, 2011, at 22:45, "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
wrote:
>
> At 07:39 PM 6/15/2011, you wrote:
>> I just got to the point where I can test my home-made audio amplifier, but it
isn't working yet, and I was hoping I might be able to get some help from those
who have built the circuit before to help narrow down the troubleshooting.
I wired it up, applied power, and it blew the 1A fuse. I looked everything
over to be sure that I didn't have any obvious shorts and couldn't find any.
Just to be sure that the rest of the wiring wasn't the problem, I removed all
of the wires except for the power and ground, but it still blows the fuse. I
went through each component and verified the placement of the ICs and resistors.
I did notice that I had one capacitor backwards, number 127, 1uF capacitor.
I reversed it but still didn't notice any difference. Is there an easy way
to test a capacitor to see if it is still good? There isn't any physical damage
to any of them.
>
> Hmmm . . . I wish I had called out sockets under the
> amplifiers so that the builder can power it up with the
> ic's out.
>
> Capacitor size is not terribly critical but polarity
> is. MOST of the times you get a hot LM317 is for
> a reversed capacitor C122.
>
> Do an ohmmeter test from pin 6 to ground on either
> of the two amplifier chips. It should be non-zero.
> Actual measurement depends on your ohmmeter and
> polarity of the ohmmeter connections. The main
> thing is that it should be some substantial number
> showing that the path is not shorted.
>
>
>
>> I replaced the fuse with my multimeter leads to try and measure how much current
it was taking, but the meter read zero, so I turned off the switch after
a second or so. After that test the 317 was warm, but not hot, and nothing seemed
to be smoking.
>
> When powered up, you should have just under 9v
> on pin 6 of the two amplifiers. I don't know how
> you heat up the LM317 with zero current. Check
> the measurement setup.
>
>
> Bob . . .
>
>
>
>
Message 2
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| Subject: | Re: Photo FET Optocoupler |
The voltage from the gauge is +5v or 0 with respect to ground. The bulb
is incandescent: 140 mW at 5 VDC, but that was what I was going to use
when I thought a direct connection to the gauge would work. Now I'll use
a #73 which is 1.12W at 14 VDC . Yes I can turn the bulb on by pulling
it to ground.
John
> ------------------------------------------------------------------------
>
> Robert L. Nuckolls, III <mailto:nuckolls.bob@aeroelectric.com>
> June 15, 2011 9:57 PM
>
>
> At 08:30 PM 6/15/2011, you wrote:
>
> Doesn't need to be a photo-fet. There are plenty of LED
> couplers that would work. Is the 5v output measured with
> respect to ground . . . and does it go to zero volts
> in the off state? Can you turn the bulb on by pulling
> its control lead to ground? 28 mA lamp sounds like an
> LED, no?
>
> Emacs!
>
>
> OOPS! You said pressure gage? Is this output a linear
> voltage that represents pressure or some voltage that is
> zero some times and 5v other times?
>
> Bob . . .
>
Message 3
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| Subject: | Re: AEC 9009 Audio Amplifier Troubleshooting Questions |
At 10:53 AM 6/16/2011, you wrote:
>
>Indeed, I had installed the 122 backwards. It works now, thanks!
You might want to consider replacing the capacitor.
Reversed polarity can have deleterious effects
on service life.
Bob . . .
Message 4
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| Subject: | Re: Photo FET Optocoupler |
At 11:11 AM 6/16/2011, you wrote:
>
>The voltage from the gauge is +5v or 0 with respect to ground. The
>bulb is incandescent: 140 mW at 5 VDC, but that was what I was going
>to use when I thought a direct connection to the gauge would work.
>Now I'll use a #73 which is 1.12W at 14 VDC . Yes I can turn the
>bulb on by pulling it to ground.
The the single transistor buffer suggested by myself
and others is a practical solution.
Bob . . .
Message 5
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| Subject: | Re: Photo FET Optocoupler |
I'm curious why Daniel recommended a 2.2K resistor and you suggested a
1K resistor.
Thanks to both for your suggestions. This looks like it should work for
me well.
John
> ------------------------------------------------------------------------
>
> Robert L. Nuckolls, III <mailto:nuckolls.bob@aeroelectric.com>
> June 16, 2011 10:20 AM
>
>
> <nuckolls.bob@aeroelectric.com>
>
>
> The the single transistor buffer suggested by myself
> and others is a practical solution.
>
>
> Bob . . .
>
>
Message 6
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| Subject: | Re: Photo FET Optocoupler |
At 12:34 PM 6/16/2011, you wrote:
>
>I'm curious why Daniel recommended a 2.2K resistor and you suggested
>a 1K resistor.
Not critical. Throw a dart and anything from 1k to 50K would probably
work.
Bob . . .
Message 7
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| Subject: | Re: Photo FET Optocoupler |
I actually thought about it, changed to a 1K, then changed back to a
2.2K before I sent it. I guess I just like the color red.. haha
On Thu, Jun 16, 2011 at 11:43 AM, Robert L. Nuckolls, III
<nuckolls.bob@aeroelectric.com> wrote:
> <nuckolls.bob@aeroelectric.com>
>
> At 12:34 PM 6/16/2011, you wrote:
>>
>> <grosseair@comcast.net>
>>
>> I'm curious why Daniel recommended a 2.2K resistor and you suggested a 1K
>> resistor.
>
> Not critical. Throw a dart and anything from 1k to 50K would probably
> work.
>
>
> Bob . . .
>
>
--
Daniel Hooper
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