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http://www.stephenhobley.com/sound.jpg
I have this circuit, the standard Velleman mk103 sound to light kit. I
would like to control 2 20w 12v lamps. I've got some TIP142
transistors that should be OK to do the switching, I just don't know
how to tap into the output to make it work.
I've been trying to tap just before the first LED but this is giving a
very limited response.
What's the best way to do it?
Steve
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Author: ehsjrDate: 16:15 29-07-08
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shobley@userfs.com wrote:
> http://www.stephenhobley.com/sound.jpg
>
> I have this circuit, the standard Velleman mk103 sound to light kit. I
> would like to control 2 20w 12v lamps. I've got some TIP142
> transistors that should be OK to do the switching, I just don't know
> how to tap into the output to make it work.
>
> I've been trying to tap just before the first LED but this is giving a
> very limited response.
>
> What's the best way to do it?
>
> Steve
Come off the collector of T4 on the existing circuit
through 1K to an optoisolator. Use that to turn the
TIP142 on/off:
4N25 +--------------+--- +13.2
------ | |
T4---[1K]---|1 6| [4.7K] |
| | | /e
Gnd(9V)-----|2 5|---+---[470R]---| TIP142
| | \c
|3 4|---+ |
------ | |
| [Lights]
| |
+--------------+--- Gnd(13.2V)
Shown is a 13.2 volt supply for the lights to make up
for the voltage drop in the TIP42.
Ed
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Author: KasterborusDate: 10:57 30-07-08
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Thanks for your help - I will try this...
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Author: KasterborusDate: 11:13 30-07-08
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On Jul 30, 10:57=A0am, Kasterborus <kasterbo...@yahoo.com> wrote:
> Thanks for your help - I will try this...
I only have the 4n29 - which appears to be a darlington arrangement -
this should drop right in to replace the '25 - correct?
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