[sdiy] Tempco vs. "Substrate Oven" in VCO and VCF

[Roman Sowa]

yes, that's heated expo pair in VCO. One transistor from 3046 array is 
used to measure Vbe in thermal feedback loop and another one is the 
heater. Maximum current is limited here to about 20mA by R18.
Service manual says to trim it to 55 deg.
I used 40 deg as minimum example, no need to go higher if there's not 
too hot inside the synth case.

Roman

W dniu 2016-02-29 o 14:48, Mattias Rickardsson pisze:
> On 29 February 2016 at 11:45, Roman Sowa <modular at go2.pl> wrote:
>> Controlled oven obviously takes more power to heat it, so that's probably
>> the reason for not so widespread solution. You need to heat it up to the
>> temperature that is not likely to happen in regular conditions, at least 40
>> deg. C. About 40-100mA to waste just on heating.
>
> 40 mA seems like a lot of current just to push the temperature up 15
> degrees... but it of course depends on how well insulated the chip is.
> The uA726 seems to draw around 7 mA in room temperature if I read the
> datasheet correctly, and I was under the impression that it's working
> at a quite high temperature.
>
> The Moog Prodigy has some heating going on in its oscillators (to the very left)
> http://www.emusic-diy.org/MoogManuals/Prodigy?action=AttachFile&do=get&target=prod9.gif
> or is it something else?
>
> /mr
>