I am always looking for interesting DIY modules. This is Gaeto from AtoVproject. The module name is derived from Gate + Legato. Multiple Gateos can be chained, and I built two. One of the functions with two chained Gaetos is a 4-bit shift register. It has two modes, normal and legato, selected by a toggling button and also a CV input. The two sections can work separately or together. An internal normalling scheme simplifies patching some of the functions. This is one of those modules where you can get creative with patch programming.

The Kit

The kit contains a 3-wire jumper cable for chaining. It also has an oddball tool that I took to be for securing the black plastic panel nuts. (See pics of the black nuts on the AtoVproject site.) I substituted standard round nuts, for which I have a nice tool.

I keep some 10-pin shrouded headers around to use on boards that don’t have them, as long as there is enough room. Just enough room on this board. The back side parts are soldered first: power header, chain mode switch, and two 3-pin headers for chaining. After soldering parts to the back side, the top side gets jacks, push buttons, and LEDs. It’s easy.

One little problem

When testing the first module, the A mode Pushbutton didn’t work. I thought at first it must be a defective switch. But when the second module had the same problem, I had to look more closely. Sure enough, a tiny SMD part (D1) was placed so that it prevented the button from making contact.

I fixed this problem in two different ways. The button cap is easily removed. My first fix was to heat the pins on D1 and nudge it a tad away from the button. This works. On the second module I thought of a better approach, which is to file down the plastic button so that it doesn’t hit D1. That had the advantage of not needing to mess with the solder on D1.

I reported this issue to AtoVproject’s tech support. They replied it is a known issue that was found after the first kits were packaged up. It’s fixed on the current revision of the PC board. They should add a note to the assembly instructions, giving a fix like the ones I did.

Dividers, Logic, and Switches case

I got a second Klavis Logica XT for this case. It’s a newer version that has a 5V regulator. The older version requires +5V from the system. There’s a Klavis NoDrain inside this case that provides +5V by converting from the -12V supply in an efficient way. It was a bit tricky getting power to all these modules, since the Pittsburgh Modular power supply has only three headers!

Update 11/30/2023

Here’s a picture of what can be observed outside of the Gaeto black box. It’s in Gate Mode (button blinking with the clock).

Green trace is the square wave clock into Gaeto. (Looks jaggy on the DATA scope, but really has sharp rise and fall edges.)
Blue trace is the output of a random step generator, clocked by the above clock. The 1V threshold seems to be a little above the center line.
Red trace is the A output.
Yellow trace is the ~A output.

It’s clear that the outputs transition at the rising clock edge. Data is unchanged until the next rising clock. It’s interesting to look at the places where the A and ~A pulses trade off.