Computer Science Student Seeks Advice on Switches & Junctions

[George Young]

TL;DR

robot for cat

Hi, I'm a computer science student and not an electronics guy (so I may not know stuff that an electronics guy would) but I took mechanics and E&M at the college level. I've been on here before but I don't have Facebook anymore so I created a new account with my Google.

For part of my simple robot design, I want to go from one wire to one of several others depending on what I've programmed my microcontroller to do. So I have the microcontroller wired up to several switches in my design - I'm guessing I could use transistors or something for those.
The microcontroller controls which switches are on to let current flow and which ones are off.

In two places I have one wire connected to many. For the above switched wires the current only goes through one at once but I'm not sure how to connect one wire to many like that.

So my first question is about how to do the junction from one wire to many or many wires to one. The second question is about whether transistors should work for the switches I described - will they, or is there a better device or method? The third question is what I should use for three way switches - A, B, or C depending on what signal the microcontroller sends out, or similarly for two way switches.

 

[Averagesupernova]

This is rather difficult to make sense of. Sorry. Can you be a bit more specific in what you are switching and what you are using to control the transistor(s)? It seems you understand part of your project (or at least think you do) and yet do not understand a different yet closely related part. Have you started with a schematic of some sort that you could post?

 

[George Young]

This is rather difficult to make sense of. Sorry. Can you be a bit more specific in what you are switching and what you are using to control the transistor(s)? It seems you understand part of your project (or at least think you do) and yet do not understand a different yet closely related part. Have you started with a schematic of some sort that you could post?

I'm just trying to figure out what parts I need to buy. I am pretty sure I can use transistors for the switches, so I no longer need an answer to that.

I just want to make my robot able to communicate with different sequences of flashing lights, but only one at a time. So, the electricity goes through one wire and will then go through whichever wire is switched on by the microcontroller.

So, the switches takes care of which wire will let current through but I need a way to make one wire branch out to multiple. There is probably a better way to do this.

 

[davenn]

I just want to make my robot able to communicate with different sequences of flashing lights, but only one at a time. So, the electricity goes through one wire and will then go through whichever wire is switched on by the microcontroller.

What do you mean by communicate ?

You need to sit down and draw a schematic of what you think you need

You should be doing this planning BEFORE deciding which components to buy

Then people here may be able to interpret it, hopefully, and guide you to what you really need

 

[anorlunda]

I'm just trying to figure out what parts I need to buy. I am pretty sure I can use transistors for the switches, so I no longer need an answer to that.

That is like saying I'm going to write a sentence. I'm pretty sure I can use words, so I no longer need to worry which words.

In other words, not all transistors are alike.

 

[Baluncore]

Welcome to PF.
We need numbers to design your circuit and select the transistor switches.
What is the logic output voltage of your microcontroller, 3V or 5V?
The switches could be N-channel logic level MOSFETs, driven directly by microcontroller, all with source tied to zero volts, ground.
What type of lights? Filament or LED? AC or DC?
What is maximum light current, what voltage is required?
What light power supply is available?
All LEDs connect to + supply, but each to a different MOSFET drain through a current limiting resistor.

 

[Baluncore]

Here is a guess at the circuit you will need. Components not yet identified.

 

[George Young]

Thanks guys. I was temporarily away. I have a design and I think I can build the circuit now. I ordered some parts yesterday but now I realize I forgot about the junction thing. I'll be back if I have more questions.

As a CPS guy my focus will be on programming the micro-controller - good experience I think.

 

[George Young]

I'm still not sure how to do the wire junctions.

So I have circuit elements A, B, C, ...

Electricity goes only to one at a time based on the microcontroller, and then each wire goes back to the battery.

The drawing illustrates how the microcontroller switches each of the transistors so the outgoing current only goes through one at a time.

The first junction (outgoing) is one wire to many. The second junction (current back to battery) is many to one. I'm not sure how to do either. For each junction, only one out of the many wires should be on at once though I might complicate it a little bit more.

 

[Baluncore]

You have not identified your lights, your switch transistors, or your supply voltages. How and where you mount those components will make a big difference to the wiring needed.

The diagram in post #7 shows symbolically what is required. The battery or power supply terminals are +supply and –supply. Each light is represented by an LED and a limiting resistor. Each switch is an NMOS transistor.

Please identify the microcontroller module you will be using.

How do you access the external I/O ports on the controller? Is there a header? or do you solder to the PCB? Are you connecting the components with wires and solder? with screw terminals? or with a plugboard?