[sdiy] can I make this circuit change?

[db]

I did try this, and with about 80k it kinda works, but the light is on a 
tiny bit, and then goes on a little brighter with audio signal .
Not really enough of a change in brightness to be usable.



At 1/17/2009 09:42 PM, Oren Leavitt wrote:
>Hi db again,
>
>Following up on my previous email...
>Easier still, you might try adding a resistor between V+ and Q101's base. 
>Try about 68K for a start. The aim here is to pull the DC voltage at 
>Q101's base up just shy of the 1.2V bias needed to turn on the 
>transistors. A small added AC signal will be enough light the LED. You can 
>tweak this added resistor to set the desired sensitivity without having to 
>change any other [arts of the circuit.
>
>OTOH, as Mark said, you may want to keep the overload indicator as is and 
>just add new circuitry for an additional "signal present" indicator LED.
>
>- Oren
>
>
>db wrote:
>>
>>On the schematic here:
>>http://workingdistance.com/temp/mixer.jpg
>>I lowered to r104 to 1k, and even then still not quite enough to light 
>>the led on regular signal levels. :(
>>I normally keep input gain (VR101) all the way down.
>>I don't really understand how in this circuit the gain knob affects the 
>>led - it looks to me like the signal to the led circuit would be the same 
>>regardless of gain setting.
>>What am I missing?
>>Anything else I can try in this circuit to get some more ooomph to the leds?
>>I have 16 channels to do so I'm hoping for simple..
>>  >I have a mixer with an input led for *overload*.
>>  >I was going to add LEDs for showing signal is present in the input, 
>> but seems easier if I just make this led signal regular input instead of 
>> overload.
>>
>>dennis.barton:skylab2000[socal]
>>
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dennis.barton:skylab2000[socal]