[sdiy] Overdriving 4007

[Seb Francis]

Interesting .. definitely sounds the way to go for a battery operated 
device.

harrybissell wrote:

>1) use two packages...
>
>2) switch to the 4007 which has two complementary pairs
>plus inverter. With the two pairs, you can add what would
>be called 'emitter resistors' in a comp symmetry audio amp...
>
>series resistor from the output of the N, and a series resistor from
>the P... take your output from the center tap.
>
>Set the idle current you want with the two resistors.  With like
>1M feedback they could be 500 ohms or so. Now the dissipation is
>controllable.
>
>Use the "inverter" section for stage three, which should draw the least
>power.
>
>This would require two packages for a two channel solution as well...
>
>H^) harry
>
>Seb Francis wrote:
>  
>
>>Harry Bissell Jr wrote:
>>
>>    
>>
>>>One other problem might be that you are using two stages
>>>in linear mode. These will get hotter than normal. Make sure it
>>>does not run TOO hot. Its probably Ok.
>>>
>>>The resistors do not limit this power... it flows from N to P channel
>>>device
>>>which are both 'half on'. It will be worst with no signal input
>>>
>>>      
>>>
>>Yeah I did notice it uses a lot of current .. about 28mA with no
>>signal.  This could be a problem because I plan to use the other 3
>>buffers for a 2nd channel of distortion.  When 28mA was measured the
>>other 3 inputs were hooked to 0V, so I'd imagine it would take more like
>>56mA when using all 6 buffers.  This equates to 840mW at 15V (the
>>absolute maximum is dissipation on the datasheet is 700mW).
>>
>>Any way round this?  A heatsink perhaps?
>>
>>Seb
>>    
>>
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