[sdiy] Overdriving 4069UB

[Seb Francis]

Scott Gravenhorst wrote:

>Harry Bissell Jr <harrybissell at prodigy.net> wrote:
>  
>
>>Content-transfer-encoding: 8BIT
>>
>>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
>> 
>> H^) harry
>>    
>>
>
>I'm thinking of trying a +/-5Volt supply version where I can then run the 4069UB (or 4007) and  the
>opamp from the same supplies.  Lowering the voltage from 15 to 10 will produce less heat.  I've
>made several circuits using 4069UB inverters in linear mode and with only mild heat.  However,
>those were devices that did not have a chance for outputs to sit halfway between the supply rails.  
>
>Just letting it sit powered up with no input is the worst case test for heat production.
>  
>
I don't think it's a problem when using only 3 of the inverters.  Mine's 
been switched on with no input for a while now and is only just warm to 
touch (the DIP version can dissipate 700mW).  I think using all 6 
however will be too much..

Of course, if you're running it from batteries, then this kind of power 
consumption probably is a problem!

Seb