I am new to electronics as you will see when you look at my attached diagram. I am attempting to run multiple circuits off one power supply. It has three wires "Gnd",12V and 5 V. All the "grounds" are tied together. What I have here is simplified (I also have a raspberry Pi running off the 5V) in an attempt to answer one question, should there be any diodes in these circuits?

 

No diodes are needed in this arrangement.
You would probably need a diode if you have one item running from two power sources (e.g. a battery and a wall wart) to stop one power source feeding into the other source.

 

Perfect, thanks for the reply!

 

Welcome to AAC!

When I looked at this:

I had to think a bit about what you were trying to convey.

It looked kind of like a battery, but there seemed to be two voltages coming from the same point.

Something like this would be more obvious:

When drawing schematics or block diagrams, most have a strong preference for things to flow from left to right and top to bottom.

 

When do you need a diode in a circuit?
That is the same as asking the following:

When do you need a ??? in a circuit?

Replace ??? with :

• resistor
• capacitor
• inductor
• diode
• transistor
• fuse
• MOV

and the list goes on and on.

We cannot possibly answer such a question in one AAC thread.
You need a course in electronic devices and circuit theory.

 

I believe what this comes down to is understanding what a diode actually does and then when and where to apply them in a circuit design. Even within diodes there are different types of diodes suited for different applications. It all starts with understanding diodes and how to interpret their data sheets. You don't learn to swim in the deep end of the pool.

Ron

 

Welcome to AAC!

When I looked at this:
View attachment 148653
I had to think a bit about what you were trying to convey.

It looked kind of like a battery, but there seemed to be two voltages coming from the same point.

Something like this would be more obvious:
View attachment 148654
When drawing schematics or block diagrams, most have a strong preference for things to flow from left to right and top to bottom.

Welcome to AAC!

When I looked at this:
View attachment 148653
I had to think a bit about what you were trying to convey.

It looked kind of like a battery, but there seemed to be two voltages coming from the same point.

Something like this would be more obvious:
View attachment 148654
When drawing schematics or block diagrams, most have a strong preference for things to flow from left to right and top to bottom.

Thanks very much, your drawing is much clearer than what I provided.

 

I believe what this comes down to is understanding what a diode actually does and then when and where to apply them in a circuit design. Even within diodes there are different types of diodes suited for different applications. It all starts with understanding diodes and how to interpret their data sheets. You don't learn to swim in the deep end of the pool.

Ron

Thanks for your input, as I stated I am new to electronics, but I do have some basic understanding of the types of diodes and what they do, its the application that is causing me issues. If you think the circuit I provided was "swimming in the deep end of the pool" I'm glad I didn't show you the complete project! The reason for the question was clarification, somewhere in my project it appears I have a power source feeding back into another, and thanks to AlbertHall I think I have my answer. Instead of you and MrChips (Moderator) telling me I need to learn more (da!!), take a lesson from dl234 and AlbertHall who actually provided some assistance!

 

When you are new to electronics, you need to look at a lot of circuits and try to understand what each component is doing. Once you can do this, you can answer your own question.

Bob

 

Thanks for your input, as I stated I am new to electronics, but I do have some basic understanding of the types of diodes and what they do, its the application that is causing me issues. If you think the circuit I provided was "swimming in the deep end of the pool" I'm glad I didn't show you the complete project! The reason for the question was clarification, somewhere in my project it appears I have a power source feeding back into another, and thanks to AlbertHall I think I have my answer. Instead of you and MrChips (Moderator) telling me I need to learn more (da!!), take a lesson from dl234 and AlbertHall who actually provided some assistance!

Sounds like a snarky remark coming from someone who prefers quick answers from others rather than wanting to take the time to learn fundamentals.

Sure the answer is, No, you do not need diodes.
Would it not have been better for you to be able come up with that answer on your own?