thepcman

Sorry dude, as you see i'm newbie, i did not look at the date of post :D

I will add a sharp infra distance sensor to my MB. I'll linearize it's output with respect to distance and at this point i need some guru help: If anyone had dealt with roland d-beam controller (that's actually nothing but a sharp sensor) it has a mode "active expression". When you turn on this mode, it produces some definite notes according to sensor output. But it does not go over all notes, it can follow a certain list, for ex. a Em7 over 3 octaves (E,G,B,D,E.... goes on). I wonder if it's possible to program that kind of a quantization to MB64 directly, or should i embed it to sensor output circuitry. If the second one is the solution, has anyone any ideas how to design a good interface for it??

The link you have posted expired but i think the problem is the minimum output voltage that op-amp can handle. If an op-amp's negative supply is connected to ground, it cannot guarantee (it usually won't) to go down to 0 volts. For instance, a ua741 can give minimum 1.2V, a LM358N will give 0.2-0.3V. So, even if you do not use negative voltages, you should supply the op amp negative supply with a really negative supply. The Sharp analog's can handle 30-40Hz of sudden changes, it responds continuous changes easily. The problem with them (i think) they give non-linear output wrt to distance. I was thinking today to interface it to MB, and i end up with the conclusion that an AD-Processor-DA chain should be used to calibrate and modify the output of it. I will design a simple circuit soon to handle it.

Having lived online for long long years, i can go over lots of things on seconds dude :P The thing is suitable for a computer based application, but my aim is to integrate the touchpad as a small module into the MB. If i cannot integrate a touchpad, i'll try to build a low cost touchpad myself (a resistive multilayer surface and a PIC to analyze it). But that kind of thing won't do the job for me.

100k is a comparable impedance to PIC analog input. If you MUST use it, adding buffer circuit will solve the problem.

I've found few documents about the issue, synaptics has a document discussing the interface, but the thing seems complicated to build a low cost solution. Devices use PS/2 interface and the data string is explained. But in fact i don't wanna deal with that kind of stuff, there should be an easier way :)

I'm now designing my own MB64 as a live control surface to my midi setup. I have an old Toshiba Satellite SM30 lap-top which includes a synaptics touchpad. It'd be amazing if i managed to interface it to MB as an X-Y controller. Anyone have any ideas how to interface it? Should i use digital interface of the touchpad and design a serial input slave device or hack the touchpad and find out analog signals?

OK Here's a complete PS: regulator.JPG regulator.JPG

Hi, I'm a newbie already, have little to talk about the project itself, but i've realised a power supply issue on the designs. The Core is equipped with 7805, which is a lossy regulator and warms up when loaded above 50% capacity (that's over 400mA or so). This warm up issue also depends on what is the input voltage to the system (that's what the output of the wall adapter is).There are designs which include lots of modules, pots, faders etc, which will load the regulator and may blow it up suddenly. Instead, there's a good option. LM2575-5V / LM2576-5V Simple switcher regulators use simple buck topology (voltage step down) to regulate output to desired voltage. LM2575 has 1A guaranteed output current and the efficiency is about 88%. LM2576 has 3A guaranteed output current and has efficiency about 76%. All they need to operate is an inductor (330uH for 2575, 100uH for 2576), an input and an output capacitor (330uF is enough for all) and a schottky diode (1N5819 for 2575, 1n5822 for 2576). The IC's work with standard inductor packages. I've used those for various circuits which include PIC's, LCD's, 74/4000 series IC's and some other stuff. I even drove a waterpump with 1A current. The output voltage is clean enough to work with digital/analog IC's. I have not measured ripples higher than 20mV!! Another good thing about using switching regulators is you can use smaller wall adapter. As the regulator very low loss and wide input voltage range (upto 40V), say if you need an output 5V 1A, for 7805 regulator, you need a 1-1.1A output adapter (7805 probably won't give 1A output, it fails about 0.8A). But if you are feeding the box via an 12VDC adapter, a 500mA adapter will do it very well if you use 2575. Here's a datasheet link for LM2575: http://www.datasheetcatalog.org/datasheets2/20/200304_1.pdf