Search found 8 matches

by Jeffin90620
Mon Sep 21, 2015 2:39 am
Forum: Build
Topic: Simple pcb design program
Replies: 28
Views: 40807

Re: Simple pcb design program

I use PCB123. It is free and, yes, its files are proprietary to Sunstone (a PCB manufacturer in Oregon), but they will sell you the Gerbers for either $50 or $100 if you want to use another manufacturer (I've seen both prices, but don't know the criteria). Learning it was fairly intuitive and their ...
by Jeffin90620
Sun Oct 04, 2009 4:17 pm
Forum: Pro Audio Design
Topic: THAT1646 Current Booster and Transformer Driver
Replies: 45
Views: 108082

Re: THAT1646 Current Booster and Transformer Driver

I'm not happy about high temperature design, either. I usually design automated test stations that run at room temperature. It looks like the AD8139 will do the trick. If I keep the supply at 7V, it can run all the way up to 125C. Wish I had better SPICE models for real-world transformers, however; ...
by Jeffin90620
Sun Oct 04, 2009 3:21 pm
Forum: Pro Audio Design
Topic: THAT1646 Current Booster and Transformer Driver
Replies: 45
Views: 108082

Re: THAT1646 Current Booster and Transformer Driver

The nominal supply voltage is 27.5V, but it has to operate down to 17V.

To minimize power dissipation (so it will work at higher temperatures), I am trying to keep the supply at 7 volts.


Jeff
by Jeffin90620
Sun Oct 04, 2009 1:42 pm
Forum: Pro Audio Design
Topic: THAT1646 Current Booster and Transformer Driver
Replies: 45
Views: 108082

Re: THAT1646 Current Booster and Transformer Driver

As a reference, the new stereo offering from FCS uses the Carnhill transformers and have a 3dB down point of 9Hz. My application is an intercom circuit for cargo airplanes, so I don't need to go that low. The Pico transformers were chosen because they have stock on units that meet the extended temp...
by Jeffin90620
Sun Oct 04, 2009 1:40 pm
Forum: Pro Audio Design
Topic: THAT1646 Current Booster and Transformer Driver
Replies: 45
Views: 108082

Re: THAT1646 Current Booster and Transformer Driver

At 150 Ohms, it gets more critical. I use 600 Ohm primaries in my builds. I have chosen a 150 ohm primary to minimize the supply voltage requirements in the driver (to minimize power dissipation at higher temperatures). I had passed on the 1646 in favor of a dual rail-to-rail opamp (buffer and inve...
by Jeffin90620
Sun Oct 04, 2009 1:27 pm
Forum: Pro Audio Design
Topic: THAT1646 Current Booster and Transformer Driver
Replies: 45
Views: 108082

Re: THAT1646 Current Booster and Transformer Driver

raf wrote: That transformer you mention, from Pico?
Here it is: http://www.picoelectronics.com/surface/ ... rtNo=83065
by Jeffin90620
Sun Oct 04, 2009 12:09 pm
Forum: Pro Audio Design
Topic: THAT1646 Current Booster and Transformer Driver
Replies: 45
Views: 108082

Re: THAT1646 Current Booster and Transformer Driver

Hhmmm... I am concerned about saturation of the transformer's core. In one application I have (a 150:150 Ohm model from Pico), the DC resistance is only 12 ohms, so it wouldn't take much of an offset differential to drive a considerable DC current through the primary. Still and all, the transformer ...
by Jeffin90620
Sun Oct 04, 2009 11:45 am
Forum: Pro Audio Design
Topic: THAT1646 Current Booster and Transformer Driver
Replies: 45
Views: 108082

Re: THAT1646 Current Booster and Transformer Driver

I notice that your schematic doesn't show any Common Mode Offset Reduction in the output.

Did you omit it for clarity, or just ignore it? Or does this off-book use eliminate it?

Regards,

Jeff