[sdiy] Latvian CEM Synth IC clones

[Roman Sowa]

Why not use TL064, or TL034 if lower input offset voltage needed

Roman

W dniu 2018-03-21 o 10:41, Mattias Rickardsson pisze:
> On 19 March 2018 at 23:48, Jay Schwichtenberg <jschwich53 at comcast.net 
> <mailto:jschwich53 at comcast.net>> wrote:
> 
>     To me it seems like chips running at 50C-60C is way too hot and
>     something is wrong. I'd expect to see something like a voltage
>     regulator dropping a lot of voltage under a decent load doing that.
> 
> 
> 55-60 degrees C was measured in the absolute middle of the top of the 
> IC, and the edges are a bit cooler. The PCB around it is 45 degrees, so 
> it's just 10-15 degrees above that.
> 
>     ____
> 
>     Are you driving low impedance loads or something?
> 
> 
> Not extremely low, maybe 10k-20k on average - the quiescent currents are 
> still the majority of currents drawn by the ICs.
> 
> But it adds up to some heat when having lots of TTSOP quad op-amps and 
> SOIC VCAs in a fairly small area, and all the passives on the bottom 
> side of the PCB.
> 
> /mr
> 
> 
> 
>     *From:*Synth-diy [mailto:synth-diy-bounces at synth-diy.org
>     <mailto:synth-diy-bounces at synth-diy.org>] *On Behalf Of *Mattias
>     Rickardsson
>     *Sent:* Monday, March 19, 2018 7:10 AM
>     *To:* mark verbos
>     *Cc:* synth-diy at synth-diy.org <mailto:synth-diy at synth-diy.org>
>     *Subject:* Re: [sdiy] Latvian CEM Synth IC clones____
> 
>     __ __
> 
>     On 14 March 2018 at 11:50, mark verbos <markverbos at gmail.com
>     <mailto:markverbos at gmail.com>> wrote:____
> 
>     Sorry if this is a stupid question, but when does it start to be an
>     issue that the parts are too small. I mean in terms of current
>     capacity and such. ____
> 
>     __ __
> 
>     One problem resulting from the tinyfication of everything is that
>     the temperature gets higher when many ICs are packed into a small
>     PCB area. My VCAs are running at over 50 degrees C here on the
>     bench. The op-amps are approaching 60 degrees. When something
>     reaches 180 degrees, we have an uncool audio fatality. ;-)____
> 
>     __ __
> 
>         I use 0603 resistors and they are only 100mW at some point it
>         starts to be an issue for analog circuits, right? Not that I
>         really want to use 01005 passives anyway, but my pick ’n' place
>         is supposed to be able to. They look like salt and pepper.____
> 
>     __ __
> 
>     Surface-mount resistors with larger physical size typically have a
>     bit lower excess noise and distortion. Size matters also among
>     capacitors to some degrees. For some designs this can be important.____
> 
>     __ __
> 
>     The ability to probe your ICs without shorting things is a good
>     goal. With quad op-amps (outputs on the corner pins) TTSOP is fine,
>     but otherwise I prefer the huge SOIC to reduce the risks.____
> 
>     __ __
> 
>     /mr____
> 
>     __ __
> 
> 
> 
> 
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