[sdiy] RE: Re: [sdiy] Overdriving 4069UB

[Scott Gravenhorst]

Seb Francis <seb at burnit.co.uk> wrote:
>René Schmitz wrote:
>
>> Hi Bbob,
>>
>> rdrake wrote:
>>
>>> René Schmitz has a VCO based on the 4069 
>>> (http://www.uni-bonn.de/~uzs159/vco4069.html); he mentions that the 
>>> chip runs hot at 15 volts but apparently doesn't burn up.  I've got 2 
>>> running at 12 volts and have never noticed any heat issue at all.
>>
>>
>> It gets a little warm, but here only two gates are used in the linear 
>> mode.
>> But I use 3 gates with my threephase LFO also @15V, and this seems to 
>> work fine also.
>>
>For this at least the datasheet gives a useful spec.  The absolute max 
>power dissipation for a DIP package is 700mW.  So measure the VDD 
>current drawn (with no signal - worst case for linear mode use), and 
>mutiple by VDD.  In my case, using 3 gates in linear mode drew 28mA at 
>15V (=420mW) and ran warm to touch (but not painful!)

My personal opinion is that this (about half the package dissipation) is
the maximum that _I_ would go.  Your milage may vary...

I'm thinking of trying the Happy Harry idea of just plain old 5 volts. 
You'd drop the current to 1/3 (hence the power dissipation would also drop
to 1/3) and then you could probably run both distortion circuits from one
package.

LM324 works down to 3 volts.  I have only TI datasheets for TL0x opamps,
and they don't give a minimum supply voltage.



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