I’ve been testing the DC-1248 (12Volts to 48Volts Phantom Power) the past few days now, and I was able to further improve performance by reducing ripple down to 128mV, for a 47.7Volts output, fully loaded drawing at 57mA.  Efficiency is computed to be at 76% at this loading.

I reduced the ripple by adding another 0.1uf ceramic and 47uf electrolytic capacitor to the DC-1248 output terminals.  Since there is no more space on the DC-1248 board (measuring only 1″x1″), I added these parts to our FAB1215 PSU Module.  So here’s the new Rev.B design.

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I got my prototype boards for my DC-1248 (12Volts to 48Volts DC-DC Converter).  Quickly built a prototype, and nervously turning on the power, there was no smoke, fyring bacon sound, or anything getting hot.  Yey! So far so good… Measured the output voltage and it was 48.2 Volts. Nice.

I began loading the DC-DC converter and looking at it’s ripple waveform on my scope. Happy to say that performance improved significantly just by moving it from a breadboard into a properly designed PCB!  The board is a tiny 1″x1″ square, with (4) Millmax pins so you can easily plug-it in to our FAB1215 Power Supply Board.

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The FAB4312 is a standard Non-Inverting Amplifier using OpAmps, accommodating both the PDIP8 IC format, and the API 2520-footprint Discrete OpAmp format.

If you’ll be installing a Discrete OpAmp, MillMax sockets are required to be installed on the board.  An external connection, RGAIN, is required to control the gain of this amplifier. One typically uses a 10K or 22K Reverse Log Potentiometer for RGAIN in this circuit configuration.

Feel free to change the values of RF, RGAIN and R3 to suit your purpose. The formula for Voltage Gain for the amplifier is conveniently printed on the FAB Module.

For CF, we’re using a 100pf C0G NPO ceramic capacitor. You may have to adjust this capacitor value to suit the OpAmp you’ll be using in case you encounter instability or oscillations.

In addition, a trimmer resistor (R2) is provided to let you adjust DC Offset Voltage as close as possible to 0 Volts. By adjusting the DC offset to as little as possible, you reduce clicking noise when changing gain settings. This may not be an issue if you’ll be using a potentiometer for RGAIN, but if you’ll be using a selector switch to vary the value of RGAIN, then you’d want your DC offset as small as possible.

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This is another Input Transformer Module, designed for use with Carnhill/UK transformers.

Just like the FAB2110 Input Transformer Module (CAN Transformer), this also features a Power Input Headers to connect V+, V- and 48Volts to our Power Supply Module.

A separate Carnhill PCB Adapter is required to mount the transformer on the board.

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For those times when you want to  experiment using your own circuit design in the FAB universe, we offer the FAB9100 BreadBoard Module.

All holes/pads are standard 0.1″ pitch. And all power rails (V+, V-, and +48V) are automatically routed for you from the Input Headers to the Output Headers. (That way, all FAB modules down the chain still get their power. We don’t want you to forget supplying power for them!)

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