[sdiy] uA726, heated pairs...

[Grant Richter]

Do you remember what you did with the substrate pin?

open, ground or -15V?

> From: Tim Ressel <madhun2001 at yahoo.com>
> Date: Fri, 8 Aug 2003 09:23:59 -0700 (PDT)
> To: Grant Richter <grichter at asapnet.net>, Keith Daniel <ensign7 at e-scape.net>,
> synth-diy at dropmix.xs4all.nl
> Subject: Re: [sdiy] uA726, heated pairs...
> 
> Yo,
> 
> I use the heater circuit from AN299 on my VCOs. One
> uses a 3046, the other uses a MAT04. It works as
> advertised. I checked the circuit in an environmental
> chamber so I could verify operation up to +40C.
> 
> --tr
> 
> 
> --- Grant Richter <grichter at asapnet.net> wrote:
>>> There is the little known National Semiconductor
>> app note AN-299 (1986?),
>>> where an LM3046 transistor array is used to
>> provide a heated pair for a VCO.
>>> 
>>> I've tried it, but it seems to me that there was a
>> change in chip manufacture,
>>> and it doesn't work as advertised. The substrate
>> pin is the problem.
>>> 
>> 
>> Just a couple stray thoughts...
>> 
>> The ap note doesn't specify the pin out on the
>> CA3046. You could probably
>> get it to work by trying different combinations of
>> heater and sensor
>> transistor.
>> 
>> Also, the substrate connects to the most negative
>> voltage used, in this
>> case, it looks like ground and not -15V.
>> 
>> For a working example, see the Moog "Source" service
>> manual which used a
>> thermostated CA3046 for the expo-converter. The
>> Serge NTO and PCO also use a
>> heated CA3046.
>> 
> 
> 
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