TCP8A Power Supply


Well, this is not a real clone of the Moog power supply, but it is listed here because of the position of the frontend / user interface, meaning the power switch and the 220V~ connector. Ok, the original PSU has a connector somewhere on the back side of the lower cabinet, but the power switch, a power indicator lamp and the fuses are located on the front side like a module.
I like this idea, so I located every element of the "human interface" on the frontend like Moog did, but including the power cable connector.

As you can see a symetric power supply is provided, +15V and -15V. This is different to the original PSU which provides +12V, -6V, +/-10V and whatever else. I prefer a standard power supply for modular systems with +/-15V, where each module creates all necessary voltages from these values. This increases stability of the supply voltages and decreases the amount of necessary subunits of the PSU (the minimum in a Moog Modular ist three units, or even more for special modules).


The TCP8A PSU is a standard dual symetric ua723 (or lm723) implementation with rectifier, big capacity buckets, voltage regulator (723) and a multiturn potentiometer for output voltage adjustment. The output current is pimped by 2n3055 transistors. A dual toroidal transformer serves as source. 31 power terminals provide the voltages for the modules (see below).
The schematic can be obtained here. Attention: Clicking the circuit means acceptance of the disclaimer on page bottom!
The original circuit is much more complicated. I omitted the current supervisor and shutdown functions and the other stuff. I kept it simple.


The fuses are located at the frontend of the TCP8A like the original, but not provided for a low current lamp power supply and the main supply but for the two symetric outputs +/-15V.
I provided two indicator lamps, one for each branch. The original module provides only one indicator lamp.
I used a two phase power switch with lamp. The original switch (without lamp) looks like a one phase switch, but as I've never seen an original CP8A I can only assume this. If I'm right the original power on function is more dangerous than mine.
In contrast to the original module I provided the power cable connector at the front side, too.

Board of the module:

Picture of the identical uNet PSU (same board, only the fuses are lead out to the front panel)

Please send questions or remarks to:
Carsten Toensmann


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