Minimum Parts For A Shruthi to function

I was just going through my collection of electronic components and it occurred to me that I probably have enough parts to mostly build another Shruthi.

But I was thinking about building a Shruthi with the minimum number of parts to function, with all parameters controlled via midi. Not even a screen.

So what parts can be removed from a Shruthi without messing it up? I know that the IC that scans the buttons can’t be removed without it sending the Shruthi into firmware update mode. Also I got the impression that without pots soldered in, the IC that scans them can receive wonky values; so can that chip be removed without causing problems?

Also, if there’s been another thread like this (which is likely, but I haven’t found it) feel free to link to it.

Thanks.

> the IC that scans them can receive wonky values; so can that chip be removed without causing problems?

The IC that scans them is the main microcontroller, and without this the Shruthi is braindead.

You simply need to wire the central pad of the pots (corresponding to the wiper) to the first or third pad (ground or +5V). Then, the pots will no longer be floating - though all parameters will be reset to 0 (or 127) when the synth boots.

You can remove the 74hc595, the LEDs and the group of 8x 220R resistors in the middle of the board.

You can remove the encoder.

You can remove the buttons, resistor network and 74hc165 provided you pull high pin 7 of the microcontroller (to make it think that no button is pressed).

You can remove the MIDI out connector and the 220R resistor connected to one side of the MIDI out.

Cool. I’m drunk at the moment, so I shouldn’t be allowed near a soldering iron, but I’ll bear all that in mind.

What do you mean by pulling a pin though? Not allowing the IC connector to connect that pin? It might be more straightforward to fit the 74hc165, right?

Thanks.

http://en.wikipedia.org/wiki/Pull-up_resistor

You just need a 10k resistor between pin 7 of the MCU (or IC2 pin 9) and a +5V point.

Thanks. I’ll look into that then.

I wonder what’s the most elegant way to do it. Maybe a jumper of insulated wire soldered to the pin of the IC holder and another attached to one of the header pins, then the resistor soldered to each of them.

If you really want to be reversible, just solder IC2’s socket (without putting the chip in), and insert a resistor between its pins 9 and 16.

If you want it to permanent, do not solder IC2 and just solder the resistor across pins 9 and 16.

Oh, ok. I thought you meant the general +5V point on the board. That sounds pretty straightforward then.

All +5V points are connected.