[sdiy] [AH] Re: UA726 clone possible?

[Paul Perry]

When Jim Williams said that it matters (in his version) which transistor on 
the chip did the heating.
Which is plausible, considering the physics.
Also I remember someone in EDN magazine saying that opening the feedback 
loop on the
heater led to oscillations at .01Hz or so... that might led to slow 
troubleshooting..

paul pery Melbourne Australia

----- Original Message ----- 
From: "Stewart Pye"
Sent: Saturday, September 12, 2015 8:21 AM
Subject: Re: [sdiy] [AH] Re: UA726 clone possible?


> Hi Tom,
>
> The THAT300 is a 4 NPN transistor array. I think there is also a MAT 4 
> tranny array that Rick mentioned earlier.
>
> I've designed (on paper) a VCO that uses the THAT300 for expo converter 
> with sensor and heater. I'm planning on laying out the PCB this weekend. I 
> probably should breadboard it first, but I like living on the edge! I 
> asked THAT some questions about the maximum dissipation and they were 
> quite helpful. If you're interested I can email the reply to you. Since 
> the max Vce and Vcb voltages are 36V (compared to 15V for the LM3046) you 
> can set it up so you have a higher Vce when the heater is on, so you can 
> dissipate more power with the same current.