FAB Modules

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DC/DC Switching Power Supply with Post Linear Regulators – FAB1515 Rev.B Design – Part 2

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FAB Modules
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On my last article, I said the ripple/noise was around 9-10mV.  Sorry, I was wrong.

Voltage ripple was even LOWER than that with the post linear regulators. I didn’t bandwidth-limited the scope.

So now, with the 20Mhz BW limited button on the scope engaged, ripple voltage is a very low 1.8mV

Vnegoutput

DC/DC Switching Power Supply with Post Linear Regulators – FAB1515 Rev.B Design

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FAB Modules, FAB1000 Power Modules
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I got my prototype boards for my FAB1515 (Rev.A) Power Supply Module. I built a prototype so I can finally evaluate and test it.  I know the V+ section and V- section works independently on the breadboard. But this PCB design combines the V+ and V- section (and also adds a 48V section) and I’m not sure how all of these DC/DC converters will interact with one another (since they will be all powered from the same 12V DC source).

After building the prototype, I hooked it up to my DIY Electronic Load, oscilloscope, and (2) bench meters. One of the bench meter monitors the Voltage output, and the other one monitors the current load.  The oscilloscope monitors the DC output and ripple, and the Electronic Load allows me to vary the current draw from a few milliamps to hundreds of milliamps.

Right away, I noticed some problem… the V+ section voltage reading was jumping all over (15.1xx to 15.2xx and higher ) and wouldn’t show a steady number on my voltmeter.  Based on experience, I know the cause of this is a too high ripple voltage.  Looking at the oscilloscope confirmed my fears… the ripple voltage was very high… too high… approaching 500mV. This is CRAP! The V- section was also exhibiting high ripple voltage, though not as high as the V+ section… but still, it was high, around 300mV.

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FAB4300 – Unity BufferAmplifier Module

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FAB4000 Amplifier Modules
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The FAB4300 Module is a Unity Buffer Amplifier Module, utilizing either a PDIP8 chip, or a Discrete OpAmp.

It has a single-ended input, and a single-ended output. The output of the OpAmp is connected back to it’s inverting input (IN-), while the input signal is applied to the non-inverting input (IN+).  The output of the OpAmp basically follows whatever is the input signal applied to IN+, thus  it’s named a voltage follower.

While the FAB4300 does not offer any amplification to the input signal, it serves a very important function. The input impedance of the FAB4300 Module is very high, meaning that the FAB4300 does not load down the signal source. At the same token, the output impedance of the FAB4300 Module is very low and thus it can drive loads very efficiently without any apparent loss in signal. You can say the FAB4300 acts like an impedance bridging circuit.

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FAB2306 – Balanced Line Receiver

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FAB2000 Input Modules
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FAB2306 is our Line-Level Balanced Receiver. The FAB2306 uses a THAT 1206-series InGenius balance line receiver chip.  The THAT 1206 uses bootstrapping to raise it’s common-mode input impedance into the meg-ohm range without the noise penalty of using high value resistors. They behave like transformers, able to maintain high CMRR over a wide range of source impedance imbalances, even when fed with an unbalanced signal. But unlike traditional transformers, they offer DC-coupling, low distortion and transparent sound.

The FAB2306 Line Input Module allows you to create gear that works with line-level balanced signals.  There is no need for 48V phantom power, or -20dB padding for this module unlike the FAB2010 Mic Input Module.

FAB2306cad

 

3D Rendering of FAB2306 Line Input Module.

FAB2306-3d

 

 

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