Electronic 'breadboard' application

deicist

Hi all, I'm trying to teach myself some basic electronic circuit design using transistors, logic gates etc... I have a project in mind and was wondering if anyone could recommend a decent application that will let me put together circuits using common components. I'd prefer it to be free, and ease of use is a primary requirment since I haven't done anything ciorcuit related for years.

shwaip

are you looking for digital only, or with analog stuff too?

deicist

hmm.... well the circuit I want to design will have 3 analogue inputs, but I only want those to be either 'on' or 'off' depending on the state of the rest of the circuit.... if that makes sense.

shwaip

outputs or inputs? And if they're just on/off, you can treat them as digital for the design part.

I've used the not free version of spice+ (http://spicep.sourceforge.net/), it is very thorough, but maybe moreso than you'd like. It also does analog simulation.

At school, we used a program (not free) called logicworks to do digital design. Depending on what you want to do, and what you're targeting (discrete transistors and logic chips, or a fpga/gal chip), you can use vhdl or another hardware language to make your life easier.

deicist

3 inputs, and the output will be a combination of those inputs. Well, for simplicities sake:

I have 3 analogue inputs. I want to be able to select either:

input 1
input 1 & 2
input 2
input 2 & 3
input 3

Using some kind of 5 stage switch. The problem is I want 2 such switches. When I change one of them it needs to either change the other one at the same time, or (I guess this would be easier) disable the other one. So which ever switch I use to change my inputs becomes the 'enabled' switch and the circuit ignores the other one. I have a vague idea how I'm going to achieve this, but any input from more experienced people would be helpful.

shwaip

As a computer engineer, I would totally use a microcontroller for this. But that's how I roll.

What kind of inputs/outputs are these - are you trying to drive speakers directly (for example)?

deicist

They're guitar pickups. It's a project for a guitar playing friend of mine. He wants to be able to switch pickups from either a switch on the body of the guitar or from a floor pedal depending on his mood (I guess). I don't know much about guitars, or electronics.... but I've been meaning to get back into electronics (I did it at college many years ago) so this seemed like an ideal project. The microcontroller idea sounds good to me, I have some programming experience (VB / Delphi / pascal / a smattering of C) but have never played with programming microcontrollers. Where would I start with something like that?

shwaip

The micro would take care of all the digital switching and handling the two switches - you'd still need analog circuitry for adding the two inputs together.

Also, often times unless you're very careful about wiring, component placement, grounding, shielding, etc, you (or your friend) isn't going to get the audio quality that he is used to. Not saying you shouldn't do this, just a heads-up.

For micros, I like to use microchip's pic line. There's a free c-compiler for most pics out there. The "tough" part is getting the code from the pc to the micro - you'll need to build a programmer (fairly simple).

I take back the micro suggestion - it's probably about as easy both ways.

What I'd do is build a simpler version first. One switch that switches between 1, 2 or 1&2. See how it sounds. And if you want to post your vague idea, I'd give it a look too.

deicist

There's already a switch on the guitar that switches between the various pickups, the difficult (and new part) is having another switch on the floor and being able to use both at the same time... I'm guessing the one in the guitar is an actual mechanical switch which physically connects and disconnects the various pickups so the tricky thing is having 2 switches that can do that. One idea I came up with (which might be too fiddly for a playing environment) is to have 2 rows of 3 LEDS mounted on the guitar. a 'current' setting and a 'next' setting. You have a simple foot pedal and 2 buttons on the guitar. Pressing either the foot pedal or one of the buttons toggles the 'next' setting through the various options and pressing the other button 'applies' it.