[sdiy] Overdriving 4069UB

[Scott Gravenhorst]

Seb Francis <seb at burnit.co.uk> 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?

Maybe lower the supply voltage.  +/- 5V ?

If you must have 15 volts, I would do this with either 2 x 4007 or 2 x
4069UB.  I've done linear stuff with a 4069UB, but not using all six
inverters that way.  I made a dual triangle LFO with a 4069UB and it got
warm, running at 8V.  Two of the inverters were integrators, 4 were used
to make two schmitt triggers so not all the amps were linear.

>Seb
>
>

---------------------------------------------------------
- Where merit is not rewarded, excellence fades.
- Hydrogen is pointless without solar.
- What good are laws that only lawyers understand?
- The media's credibility should always be questioned.
- The only good terrorist is a dead terrorist.
- Governments do nothing well, save collect taxes.

-- Scott Gravenhorst | LegoManiac / Lego Trains / RIS 1.5
-- Linux Rex         | RedWebMail by RedStarWare
-- FatMan: home1.gte.net/res0658s/fatman/
-- NonFatMan: home1.gte.net/res0658s/electronics/
-- Autodidactic Master of Arcane and Hidden Knowledge.