Friday, 6 April 2018

Passive attenuator and reference voltage

This module combines in 4HP some utilities I first planned for a 2U utility panel.

Finished module chilling on bench

From top to bottom : a passive attenuator, two reference voltages and a manual gate.

The attenuator and the gate are normalled to the 10V reference voltage.

The reference voltage electronic schematic is scavenged from the same function in Mutable Instrument Shades.   Hence the reference to Olivier Gillet, whose work is a great source of inspiration for me.

Ongoing panel assembly

Some of the components are soldered on the panel.
I hesitated to include the 51 ohms protection resistors at the op-amps outputs.  Maybe I should have put them inside the feedback loop of the op-amps ...  Nevertheless, the  circuit was built when I thought I might add them and I did not want to  ruined my earlier work, so they ended up on the panel.

The op-amp went into smoke as soon as I began the first test : I had inverted the -12 V and + 12 V pins.  :-(
I resorted to solve it with some trace removal and a couple of wires.

Problems solved.

So no layout this time : i'm too ashamed.  :-/
Still, here is the final electrical schematic.

Passive Attenuator and Reference Voltage

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