How to prototype a PCB #3

Dear: Element 14

Never-mind I figured it out on my own here is my finished schematic.

Also if you have further comments please submit because I still have some helpful answers to reward.

From: Noah

Hi Noah,

This circuit most likely won't achieve your needs. Also, it's quite hard seeing your thought process with the 8 channels drawn like this.

As a suggestion, it's best to just create a schematic for a single channel based on some existing designs that you've been shown,

and then test it multiple times for real (use stripboard to create it). If it doesn't work, then you know the design needs some changes.

I can guarantee that otherwise you'll just be disappointed if you get a PCB fabricated and it doesn't work.

Spend a few days prototyping a single channel for real, and trying it out. Once you're 100% sure you've got your single channel

correct, then multiply your design by 8.

It's definitely a recipe for disappointment to try to develop a PCB at this point.

But, I can understand sometimes you need to learn for yourself, in which case by all means create a PCB and try it,

but I'm letting you know now this is really bad practise not to test first (and you'll definitely learn this on your first PCB).

I definitely agree with Shabaz on this one Noah, your still trying to run before you can walk, You need to understand transistors and other electronics before you start committing them to a PCB

you appear to have these transistors wired in an emitter follower configuration and as such the output will never rise to more than .7v below the logic used to drive them.

As Shabaz has suggested, use a solder less breadboard or strip board and actually build one of the circuits so you can understand how it works

also you should read all of the following articles, they will help you in your understanding, or at least get you a better idea of the circuit you will need

http://www.electronics-tutorials.ws/transistor/tran_1.html

http://www.electronics-tutorials.ws/transistor/tran_2.html

http://www.electronics-tutorials.ws/transistor/tran_4.html

read the others too if you want but atleast read these three

and then try to test some of the circuit theory on a bread board

Peter

Dear: Peter and Shabaz

I tried doing some experimenting to see weather or not how to do what you guys said but I can't figure out how to connect these all to one channel and to also connect them to the detonate wire. Can you please help me?
From: Noah

Dear: Peter and Shabaz

Does this look good because I am not sure?

From: Noah

Hi Noah,

You can't expect to design such a circuit from scratch without doing basic stuff first. It's like open heart surgery before learning where the

heart is. For this reason, the best advice is to abort the complex design, and either spend time learning with simple circuits not related to the

launch controller, or just use someone else's single-channel design for now. You could expand it later.

Your transistor design will not work. You need to pass a high amount of current, which is not possible with the single transistor design.

The SCR design I'm not going to try to decipher, mainly because I suspect you've again just tried guessing.

The robotroom.com design already controls a rocket. You should re-use that design until you're competent to modify it, and multiply it by 8.

It's not a perfect design but it works and has been proven by the creator.

If you still want to forge ahead with your own endeavors, the steps below are about the minimum you'd have to do. As a strong suggestion, abort the idea

of creating a PCB with an Arduino on it. Just use an existing Arduino board. It is only worth reinventing the wheel after a lot of practice and experience.

Do it in steps, here are some examples, but come up with your own plan based on your speed and what experience you have:

Step 1: Get your off-the-shelf Arduino board to control an LED on proto/strip board. This ensures you know how to control the LED using Arduino code

Step 2: Add a switch, and test your code

Step 3: (or earlier) Definitely read up on transistors such as the links above

Step 4: Replace the LED with a circuit that controls a relay. You'll need a transistor for this. There will be lots of examples of this on the Internet, so this is a good exercise for you.

Step 5: Use the relay to test your igniter for real. If this works, then you've got a circuit that works. Now try to double the circuit, and control two rockets.

Step 6; Now draw the entire circuit but for 8 rockets, not 2. Follow some standard rules, such as:

               * Ground at the bottom, positive supply rails at the top

               *  Easy to read - no mess of wires. This means align all the parts nicely

               * Use an existing Arduino - do not try to design your own at this stage, it is too early

               * Look at the robotroom.com launch controller schematic at the link in a different thread - the guy has trailblazed for you, you can benefit from his experience

It is not an easy thing to skip these steps and assume a complete rocket controller can be built - it's not easy, it needs some practice with simpler circuits first, then move on

to control a relay, then control your rocket.

There are many resources to teach Arduino and basic circuits, so it is only right that you try those first and gain experience (I mean over the period of months - it doesn't

come within a few days).

If you can complete up to Step 5, then Step 6 is easy since you're just multiplying what you already have confirmed to work.

Noah, I have to concur with Shabaz, even with my experience I still build out the design first on a breadboard, then migrate them to strip-board or if im making a few, to an etched PCB design. I have been doing this for 40 Years and I still follow that practice

And on top of that I build the Ideas up from Basics, look at the three video's I just posted, they where basically a record of a few of the steps I went through designing my interface for the Electronic Referee, and even with this it is not handling massive power, just 24V circuitry. I build a single channel, then 4, then migrated to strip-boards * 2.. I make less mistakes that way and have confidence the design will work

Regards

peter